# Console Trashcan User’s Guide

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# Console Trashcan (ctrash)

Copyright © 2015-2020 Mahlon R. Smith, The Software Samurai This manual describes version 0.0.06 of ’ctrash’. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled  "GNU Free Documentation License".

’ctrash’ provides command-line access to the system local Trashcan
for both trash and restore operations as well as
Trashcan content reporting.

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## Introduction

#### What is cTrash?

cTrash (ctrash) is a simple, console (command-line) utility which provides direct access to the user’s system local Trashcan.

The Trashcan is a directory structure that contains files and directory trees which have been provisionally deleted through an application or process on your GNU/Linux system.

#### Why We Need cTrash

cTrash (ctrash) helps to tame the power of the command line interface. Using the GNU/Linux console interface, a talented user can create elegant, even artistic command sequences. However, any user can unintentionally abuse the console interface to cause significant damage to his or her data, or to the system itself.

Using cTrash in addition to, or as a replacement for the ’rm’, ’rmdir’, ’unlink’ and other console utilities, can help to reduce accidental chaos by provisionally deleting files and directory trees rather than sending them directly to oblivion.

Traditionally, the Linux Trashcan has not been available from the console, nor through console applications. We believe this to be a major design oversight.

Other individuals and groups have devised various solutions for this problem, notably the 'trash-cli' utility by Andrea Francia and Einar Orn Olason, which works, but is unfortunately a Python hack with some user-friendliness issues.

cTrash is a real application with error checking, user interaction, meaningful documentation and other useful features.

cTrash is demonstrably superior in every way to the Nautilus (aka ’Files’) Trashcan manager. Make the move, you’ll be glad you did.

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## Operational Overview

cTrash (ctrash) is a console-based (command-line) utility for managing the contents of the user’s local Trashcan.

cTrash is designed as a safer, and more flexible alternative to the 'rm' and 'rmdir' commands. The following operations are supported.

• Move files and directory trees to the Trashcan.
• Restore items from the Trashcan.
• Report statistical data on the contents of the Trashcan.
• Empty the Trashcan.
• Emulate the operation of the 'rm' command without risking the loss of important data.

#### Recognized file types

• Regular files. This includes most files that you will access on a daily basis.
• Directories, either empty directories, or directories containing other files and subdirectories
• Symbolic Link files. Note that if a symbolic link file is specified, the symlink itself will be moved to the Trashcan, and NOT the link target.
• FIFO files (first-in-first-out named pipes).
• NOT processed by cTrash are Character Device files, Block Device files, Socket files and operating-system-specific file types. Moving files of these types could damage your operating system.

cTrash is designed specifically to protect your data and to do as little damage as possible.

• If conflicting command-line options are specified, the option which has the least effect on the data will be used, and other options will be ignored.
• cTrash will not modify protected data.

The same rules apply to restoring items from the Trashcan. If an existing target item is found, then you must have read/write access in order to overwrite it during restoration.

• Multiple levels of confirmation may be specified via command-line options; however, the default is to ask for confirmation before performing any action that cannot be undone.

The '--preconfirm' option is available to view and confirm the operation to be performed before any data are modified.

• If you accidentally send an item or items to the Trashcan, then the '-r' option is available to undo the most recent move to the Trashcan.
• The '--verbose' option provides detailed information so you can closely monitor the operation.

#### Example output

By default cTrash will report summary results of the operation.

Invocation: ----------- ctrash selfie01.jpg selfie02.jpg selfie03.jpg MySelfies Summary Output (success): ------------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- OK: 4 items (12 files) moved to Trashcan. Invocation: ----------- ctrash unobtainium Summary Output (failure): ------------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Error! Specified source item, 'unobtainium' was not found.

The output produced by cTrash may be adjusted using the options:
'--verbose' , '--quiet' , '--silent'

#### Note on formatted numeric output

File size, disk space and similar numeric values are expressed as bytes, kilobytes, megabytes and gigabytes. While this may seem obvious, it is important to be clear that these are powers-of-10 (decimal) values, NOT powers-of-2 (binary) values. This reflects the standards used by the disk industry to describe their products.

Decimal Values Binary Values --------------------------- ------------------------------- kilobytes (x/1000) NOT kibibytes (x/1024), megabytes (x/1000000) NOT mebibytes (x/1024000) gigabytes (x/1000000000), NOT gibibytes (x/1024000000). terabytes (x/1000000000000), NOT tebibytes (x/1024000000000).

Operating systems are inconsistent in the way they report such values. A notable exception is Ubuntu which has been applying the correct prefixes since version 10.10, while Windoze(tm), of course is consistently wrong. (shocking! :-)

#### Recursive operations

cTrash processes non-empty directories recursively; that is, each level of the directory tree is processed in turn.

• cTrash WILL NOT recurse into a different filesystem.

If you specify a subdirectory name as an item to be moved to the trash, then that directory and all its contents must live in the same filesystem. If any file in the source directory is located on a different filesystem, then no data will be moved for that directory item.

• cTrash WILL NOT attempt to move a directory which contains the Trashcan directory to the Trashcan.
(This includes the root directory, which contains everything.)

#### Calling cTrash from within another application

cTrash is a typical console utility in that you may invoke it from a script file, or from within another application.

All output is ’wide character’ data transmitted through the standard output stream. In C++ terms this is 'wcout' (or for those who cling to C, 'wprintf').

Output may be redirected in the usual way to a temporary file or to a RAM buffer for later parsing or reformatting by your application.

NOTE: In a future release we plan to provide an option to build cTrash as a link library, for tight integration with applications requiring Trashcan access.

#### Note on redirection

cTrash sends no output to the ’stderr’ stream, only to the ’stdout’ stream; therefore, if desired, all output may be silenced by redirecting ’stdout’ to the bit bucket. (ctrash *.o 1>/dev/null)

However, this redirection is not recommended because if a user confirmation is requested, the application would appear to hang while waiting for a user response. For this reason if you want no output to be produced, please use the '--silent' option to disable all output AND all confirmation requests.

If you want to redirect the output to a file for later use, remember to disable user confirmation requests using the '--no-confirm' option.
Example: ctrash -S --no-confirm 1>trash_contents.txt

#### Value returned to the command shell

cTrash returns the number of items (NOT the number of files) successfully processed.

OperationReturns
Move to Trashcan number of items successfully moved
Restore from Trashcan number of items successfully restored
Empty Trashcan number of items successfully deleted
Trashcan Report number of items currently in Trashcan
’rm’ Emulation Mode — ZERO (0) if all specified items moved
— non-ZERO (-1) if one or more errors
Returns (-1)
(pre-processing error)
— one or more invalid command-line options, or invalid argument for options that require them

Important Note: In the case of a pre-processing error, no data will be processed. If there is an unexpected error after processing begins, then some specified items may remain unprocessed. Either way, an appropriate diagnostic message will be generated.

#### Technical details of Trashcan operations

Please see Tech Notes for details on the structure of the Trashcan and how cTrash manages Trashcan operations.

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## Invoking

### Summary of Options

OPTION  DESCRIPTION
't' option Move item(s) to Trashcan  (default option and optional)
'r' option Restore item(s) from Trashcan  (undo most recent deletion)
'R' option Restore item(s) from Trashcan  (interactive restore)
'e' option Empty the Trashcan     (delete all items)
'E' option Empty the Trashcan     (interactive deletion)
's' option Report Trashcan contents  (summary report)
'S' option Report Trashcan contents  (detailed report)
'p' option Confirm before operation  (short form)
'v' option Verbose output (short form)  (detailed reporting)
'q' option Produce output only on error  (short form)
'd' option Delete items instead of  sending to Trash (short form)
'h' option Display a list of all cTrash  options (short form)
'verbose' option Verbose output       (detailed reporting)
'quiet' option Produce output only on error  (or critical user prompt)
'silent' option Produce no output         (not even if errors)
'preconfirm' option Confirm before performing  specified operation
'no-confirm' option Never ask for confirmation  for an operation
'remove' option Remove items from Trashcan  based on deletion date
'sort' option Set sort option for output  of item lists
'file-list' option Specify a list of files to be  sent to Trashcan
'alt-target' option Specify an alternate path for  restoring item from Trashcan
'trash-path' option Specify a non-default  location for Trashcan
'delete' option Delete items instead of  sending them to Trashcan
'rm-emulate' option Emulate options for the ’rm’  utility
'stat-cols' option Specify column-width for  output to display
'version' option Reports the cTrash version  number and copyright info
'help' option Display a list of all cTrash  options

### Usage

    ctrash [OPTIONS] [FILENAMES]


Options and filenames may be specified in any order. (exception: '--rm-emulate' option)

Example:
ctrash Cow.jpg Horse.jpg --verbose Pig.jpg -p


However, some options take precedence over other options, regardless of the order in which they are specified. For conflicting options, the option selected for processing is the option which will have the least effect on the data, and options of lower precedence will be ignored.

Of course these overrides are not applicable when ’ctrash’ is invoked as designed, but it is useful to know what will happen if you accidentally specify conflicting options. The table below lists options in order of precedence, high-to-low.

--version Overrides everything --help or -h Overrides everything except '--version' -S Statistics report (detail) -s Statistics report (summary) -R Restore from trashcan (interactive) -r Restore from trashcan (most recent deletion) -t Send item to trashcan (optional argument)  (option is implied by presence of item names) -E Empty trashcan (interactive) --remove Empty trashcan (according to deletion date) -e Empty trashcan (empty all) --verbose or -v Overrides '--quiet', '-q' and '--silent' --quiet or -q Overrides '--silent' --preconfirm or -p Overrides '--quiet', '-q' --rm-emulate If not the first argument specified, it will be interpreted as an invalid argument.

Short-form options may be combined into a single token.

Example:
ctrash -tpdv MyMomCanNeverSeeThisPhoto.jpg


For options which require arguments, the option must be immediately followed by the EQUAL sign (’=’) which must be immediately followed by its argument. If the argument string contains space characters, enclose it in parentheses.

Example:
ctrash --trash-path='/run/media/sam/BACKUP DRIVE/Trash' *.jpg


It is often said that under Linux, everything is a file, and to some extent this is true. However, not all files can be handled in the same way. cTrash supports the four most common file types.

• Regular files
• Directories (either empty directories, or directory trees)
• FIFO files (first-in-first-out named pipes)
• Character Device files, Block Device files, Socket files and operating-system-specific files ARE NOT supported by cTrash, and if specified, will will not be processed.

### Options

–t (optional, default) Send source items to the Trashcan.

Specify one or more items (files or directory trees) to be sent to the Trashcan. At least one source item must be specified, either directly on the command line, or through the '--file-list' option, below.

There is no practical upper limit to the number of items that may be specified, nor the size of those items; however, the total size of a recursive (directory tree) move may exceed the freespace on the target filesystem, so be aware of the size of recursive operations. If you are not certain about the size of a recursive move, then consider: 'preconfirm' option.

An item may be specified in several ways.

• its position relative to the current working directory:
Infodoc_backup.cpp
./test_data/January/log17.txt
• its absolute path:
/home/sam/Software/Infodoc/test_data/January/log17.txt
• its path expressed with simple environment-variable substitution:
${JAN_TESTDATA}/log17.txt • If the path to the source item contains spaces, then the token must be enclosed in parentheses: './my happy place/Letters from Jianjian' • Note that symbolic links in the source path will be followed, but that if the target item itself IS a symbolic link, then the symlink itself, and NOT ITS TARGET will be moved to the Trashcan. • Specifying an item more than once will cause a processing error because obviously, the second time it is processed, the item will no longer be there. • There are three(3) types of source items which cTrash will never attempt to move. • cTrash will not attempt to move a source item to the Trashcan if that item is already in the Trashcan. • cTrash will not attempt to move a source item to the Trashcan if that item contains the Trashcan directory. • cTrash will not attempt to move the root directory ( "/" ). • Attempting any such operation will generate a well-deserved error message. Note that sending items to the Trashcan is the default operation, so the '-t' option is optional. The following commands are equivalent. EXAMPLE: ctrash -t Selfie71.jpg EXAMPLE: ctrash Selfie71.jpg –r Restore the most-recently-deleted item(s) from the Trashcan. The most-recently-deleted item(s) in the Trashcan will be restored to their original location. This is an "Undo" function for items which were sent to the Trashcan by mistake. • cTrash scans the deletion date for each item in the Trashcan, and • identifies the item with the most recent timestamp, and • restores that item to its original location. • If multiple items share the same timestamp, then they all will be restored simultaneously. (Timestamp has a one-second resolution.) • Note that while cTrash uses the same deletion-date timestamp for all items sent to the Trashcan in a single operation, other applications may not be so well-organized. If you sent multiple items to the Trashcan using another application, then it is possible that their timestamps may not be identical. In this case, you would need to invoke 'ctrash -r' more than once to retrieve all the desired items. • Note: This option should not be used to restore data from a shared Trashcan. While nearly all Trashcan directories are owned and controlled by a single individual, just be aware that in some situations such as a shared family system, the Trashcan effectively becomes a shared resource. • If there is any doubt about what item(s) will be restored by this operation, then include the '--preconfirm', (pre-restore confirmation) option, OR use the '-R', (Interactive Restore) option instead. By default, cTrash will report the name and location of each restored item. To disable this report, see the --quiet option. #### Note on existing targets If cTrash detects an existing target file which will be overwritten by the item being restored, then the existing target must have the same file type as the item being restored, and you must have permission to overwrite that file. cTrash will not modify or overwrite protected data, regardless of its file type. Please see data protection for more information. #### Example of restoring the most recent deletion Send an item to the Trashcan: (with pre-confirmation and verbose output) ========================================== ctrash -pv cTrash/gString.cpp Displayed: ---------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Items To Be Moved: /home/sam/Software/cTrash/gString.cpp Move 1 items (1 files, 185Kbytes) to the trash? (y/n): _ Response: --------- y (ENTER) Summary output: --------------- OK: 1 items (1 files) moved to Trashcan. Restore the item from the Trashcan: (with pre-confirmation and summary output) ========================================== Invocation: ----------- ctrash -rp Displayed: ---------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Items To Be Restored: /home/sam/Software/cTrash/gString.cpp 1 item(s) including 1 files and 185.8Kbytes to be restored. continue? (y/n): _ Response: --------- y (ENTER) Summary Output: --------------- Restoring: /home/sam/Software/cTrash/gString.cpp 1 item(s) (1 files) restored from Trashcan. An alternate restoration directory or target filename may be specified. Please see 'alt-target' option for more information. –R Interactively restore item(s) from the Trashcan. During interactive restoration of items from the Trashcan to their original position, cTrash will display an itemized list all items in the Trashcan by their original path/filename, their size and the date they were moved to the trash. You may then select one or more items to be restored from the Trashcan to their original location(s). Selection is made by entering the item number of each item to be restored, separated by commas, then press ENTER. To abort the selection, enter ’q’ (or ’Q’), then press ENTER. By default, cTrash will report the name and location of each restored item. To disable this report, see the --quiet option. #### Note on existing targets If cTrash detects an existing target file which will be overwritten by the item being restored, then the existing target must have the same file type as the item being restored. cTrash will not modify or overwrite protected data, regardless of its file type. Please see data protection for more information. #### Example of an interactive sequence Invocation: ----------- ctrash -R Displayed: ---------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- 1) /home/sam/Documents/Texinfo/sp00.texi DeletionDate=2015-08-07T18:47:44 -- (3,697 bytes) 2) /home/sam/Documents/PS Lily 7 (ms).odt DeletionDate=2015-08-20T00:03:50 -- (57.5K bytes) 3) /home/sam/Software/cTrash/test2Trash [DIR: 8 files] DeletionDate=2015-08-27T18:43:55 -- (156K bytes) Enter the item number of each item to be restored, separated by commas. Example: 1,3,4 (or 'q' to quit) selection: _ Response: --------- 2 (ENTER) Summary output: --------------- Restoring: /home/sam/Documents/PS Lily 7 (ms).odt 1 item(s) (1 files) restored from Trashcan. An alternate restoration directory or target filename may be specified. Please see 'alt-target' option for more information. IMPORTANT NOTE: cTrash makes no attempt to check for simultaneous restoration of multiple items with the same target path/filename. If you do attempt such an ill-advised operation, then the behavior cannot be guaranteed. Logically, all items will be restored according to the sort order of displayed items. All specified items will be removed from the Trashcan and the last item restored should exist as the restored item; however, this logic cannot be trusted. Several factors may affect the actual outcome of such a move, so the short answer is: Don’t Do It! –e Empty the Trashcan. Delete ALL Trashcan contents, including any invalid Trashcan records. This operation cannot be undone. Example: ======== Invocation: ----------- ctrash -e Interactive Output: ------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Deleting all Trashcan contents. This operation cannot be undone. continue? (y/n): _ Your response: -------------- y (ENTER) Summary Output: --------------- 10 items (41 files) deleted from Trashcan. 2.250M bytes of disk space recovered. Note that because this operation cannot be reversed, the default is to prompt for confirmation before deleting the data. To disable this confirmation, see 'no-confirm' option. To selectively delete Trashcan items, see 'E' option, below. To delete Trashcan items based on the date they were sent to the trash, see 'remove' option, below. –E Delete selected items from the Trashcan. Interactively delete items from the Trashcan. This operation cannot be undone. A list of items currently in the Trashcan is displayed and you can select by item number, one or more items to be deleted. Enter the item numbers, separated by commas, then press ENTER. To delete all items, enter ’a’ (or ’A’), then press ENTER. To abort the selection, enter ’q’ (or ’Q’), then press ENTER. Example: ======== Invocation: ----------- ctrash -E Interactive Output: ------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- 1) /home/sam/Software/cTrash/gString.o DeletionDate=2015-09-12T17:00:00 -- (56.0K bytes) 2) /home/sam/Software/cTrash/Abc [DIR: 31 files] DeletionDate=2015-09-20T12:08:55 -- (1.55M bytes) 3) /home/sam/Software/cTrash/Abc/gString.cpp DeletionDate=2015-09-23T10:07:07 -- (185K bytes) Enter the item number of each item to be deleted, separated by commas. Example: 1,3,4 (or 'a' (all), or 'q' to quit) selection: _ Your response: -------------- 2 (ENTER) Deleting 1 items (32 files and 1.559M bytes) from Trashcan. This operation cannot be undone. continue? (y/n): _ Your response: -------------- y (ENTER) Summary Output: --------------- 1 items (32 files) deleted from Trashcan. 1.559M bytes of disk space recovered. Note that because this operation cannot be reversed, the default is to prompt for confirmation before deleting the data. To disable this confirmation, see 'no-confirm' option. To delete all data from the Trashcan, see 'e' option, above. To delete Trashcan items based on the date they were sent to the trash, see 'remove' option, below. –s Statistics: summary report of Trashcan contents. Display a summary of the current Trashcan contents. The data reported include the following. • LOCATION: Location of the Trashcan directory on your system. This is either the default user-local Trashcan, or an alternate Trashcan specified by the 'trash-path' option. • ITEMS: Number of top-level items in the Trashcan. Top-level items may be individual files or directory names. • FILES: Total number of files in the Trashcan. This is the total of all top-level items as well as any files and subdirectory names contained within top-level directory items. • TOTAL SIZE: Combined size of all files and directories stored in the Trashcan. This value is expressed in bytes. • SIZE ON DISK: Disk space required by Trashcan contents. This is the approximate amount of space, in bytes, required to physically store the Trashcan data. This will be somewhat larger that the ’Total Size’ value because it includes the size of the item-description records as well as the space wasted due to inefficiencies inherent in the way a particular filesystem actually allocates data space on the disk. • FS FREESPACE: Available unused space on the Trashcan’s filesystem, also expressed in bytes. Note that this is not necessarily equivalent to the free space on the physical disk because a single physical disk may contain many different filesystems. We report only the free space on the filesystem which contains the Trashcan. This is typically the filesystem attached to the '/home' mountpoint. Please see formatted numeric output for information on the way cTrash represents numeric data. Example: ======== Invocation: ----------- ctrash -s Summary Output: --------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Trashcan Summary: ------------------------------------------------ LOCATION: /home/sam/.local/share/Trash ITEMS: 15 FILES: 23 TOTAL SIZE: 1.063M SIZE ON DISK: 1.178M FS FREESPACE: 249.0G –S Statistics: detailed report of Trashcan contents. List each item currently stored in the Trashcan, including its original path/filename specification, the date it was moved to the Trashcan and its size. For items which are directory names, the total number of files contained in the directory and their combined size are also reported (see item 10 in the example below.) The default sort order for item display is by deletion date, old-to-new, so the item most recently moved to the Trashcan is listed last. The sort order may be modified if desired using the 'sort' option. (see 'sort' option) Note that the path/filenames are compressed to fit within the size of the console window (see 'stat-cols' option). Following the details on each item, a summary of the Trashcan contents is appended (see the '-s' option, above). Example: ======== Invocation: ----------- ctrash -S --sort=d --stat-cols=80 Detailed Output: ---------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Trashcan Contents ------------------------------------------------------------------ 1) /home/sam/Software/Curses/Dialog/install/.../README DeletionDate=2015-07-29T11:18:31 -- (1,011 bytes) 2) /home/sam/Software/.../gString-0.0.22-infodoc.tar.bz2 DeletionDate=2015-07-29T11:18:31 -- (28.5K bytes) 3) /home/sam/Software/Curses/.../gString-0.0.22.tar.bz2 DeletionDate=2015-07-29T11:18:31 -- (54.8K bytes) 4) /home/sam/Software/Curses/Dialog/install/.../gString.cpp DeletionDate=2015-07-29T11:18:31 -- (166K bytes) 5) /home/sam/Software/Curses/Dialog/install/.../gString.hpp DeletionDate=2015-07-29T11:18:31 -- (40.9K bytes) 6) /home/sam/Software/Curses/Dialog/install/.../gs_test.cpp DeletionDate=2015-07-29T11:18:31 -- (2,012 bytes) 7) /home/sam/Software/Curses/Dialog/.../gstring.info DeletionDate=2015-07-29T11:18:31 -- (111K bytes) 8) /home/sam/Software/SourceProfiler/Texinfo/sp00.texi DeletionDate=2015-08-07T18:47:44 -- (3,697 bytes) 9) /home/sam/Teaching/2015b Fall/temp/PS Lily 7 (ms).odt DeletionDate=2015-08-20T00:03:50 -- (57.5K bytes) 10) /home/sam/Software/cTrash/test2Trash [DIR: 8 files] DeletionDate=2015-08-27T18:43:55--(156K bytes) 11) /home/sam/Software/cTrash/gstring.info DeletionDate=2015-08-30T16:50:30 -- (128K bytes) 12) /home/sam/Software/cTrash/cTrash.o DeletionDate=2015-08-30T17:04:05 -- (52.8K bytes) 13) /home/sam/Software/cTrash/cTrash.o DeletionDate=2015-08-30T17:04:19 -- (52.8K bytes) 14) /home/sam/Software/cTrash/testTrash/#cTrash.cpp# DeletionDate=2015-09-06T00:38:12 -- (103K bytes) 15) /home/sam/Software/cTrash/testTrash/cTrash.cpp DeletionDate=2015-09-06T00:38:12 -- (103K bytes) Trashcan Summary: ------------------------------------------------ LOCATION: /home/sam/.local/share/Trash ITEMS: 15 FILES: 23 TOTAL SIZE: 1.063M SIZE ON DISK: 1.178M FS FREESPACE: 249.0G –p Confirm before performing an operation. This is the short form of the 'preconfirm' option, below. –v Report detailed information on all operations. This is the short form of the 'verbose' option, below. –q Produce output only if errors occur. This is the short form of the 'quiet' option, below. –d Bypass the Trashcan and permanently delete source items. This is the short form of the 'delete' option, below. –h Display cTrash command-line help. This is the short form of the 'help' option, below. ––verbose Report detailed information on all operations. While cTrash outputs summary data by default, if you want to know more about the operation being performed, then use the '--verbose' (or '-v') option to view information on each item being processed. This option does not affect the actual operation in any way; it simply reports additional information before, during and after the operation. The examples below show the output for both a summary session and a verbose session to remove items older than ten(10) days from our test Trashcan. Note that because the operation cannot be undone, we are asked to confirm before removing the items. #### Example with summary output Invocation: ----------- ./ctrash --trash-path=testTrash --remove=10 ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Deleting 8 items (8 files and 359.0K bytes) from Trashcan. This operation cannot be undone. continue? (y/n): y 8 items (8 files) deleted from Trashcan. 359.0K bytes of disk space recovered. #### Example with verbose output Invocation: ----------- ./ctrash --trash-path=testTrash --remove=10 --verbose ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- cTrash.o (2015-09-11 14:08:26) cTrashCan.o (2015-09-11 14:08:26) cTrashFile.o (2015-09-11 14:08:26) gString.o (2015-09-11 14:08:26) cTrash.o (2015-09-12 16:04:36) cTrashCan.o (2015-09-12 16:04:36) cTrashFile.o (2015-09-12 16:04:36) gString.o (2015-09-12 17:00:00) Deleting 8 items (8 files and 359.0K bytes) from Trashcan. This operation cannot be undone. continue? (y/n): y cTrash.o (deleted) cTrashCan.o (deleted) cTrashFile.o (deleted) gString.o (deleted) cTrash.o (deleted) cTrashCan.o (deleted) cTrashFile.o (deleted) gString.o (deleted) 8 items (8 files) deleted from Trashcan. 359.0K bytes of disk space recovered. ––quiet Produce output only if errors occur. Using this option, cTrash will produce no output to the display, unless an error occurs, or if user-confirmation is required. (See 'no-confirm' option, for disabling all user confirmation.) By default, cTrash will display the application title when invoked, and will report summary results for the operation; however, the '--quiet' option can be used to produce minimal output to the display. #### Examples of quietly moving all object files to the Trashcan ctrash --quiet *.o ctrash -q *.o Please see Operational Overview for examples of default output. ––silent Produce no output even if there are errors. cTrash will produce no output to the display, not even error diagnostics. As a consequence, all interactive confirmations are also disabled. This option is primarily for use when cTrash is called from inside another application, or when invoked by your login or logout script. When this option is used, the only indication of success or failure of the operation is the value returned to the command shell on exit. Please see exit codes for a description of cTrash exit codes. ––preconfirm Confirm before performing an operation. When moving items to the Trashcan, or when restoring items from the Trashcan, ask for confirmation before actually executing the move. Use this option to get information on what will be done, before comitting to do it. Note that by default, cTrash will ask for confirmation of all actions which cannot be undone, but the 'preconfirm' option confirms before executing reversible operations as well. #### Examples: Move items to the Trashcan: --------------------------- ctrash --preconfirm source1.cpp sourc2.cpp source3.hpp ctrash -p source1.cpp sourc2.cpp source3.hpp Restore most recent deletion from Trashcan: ------------------------------------------- ctrash -rp ctrash -r --preconfirm ––no-confirm Do not confirm before executing unrecoverable actions. By default, cTrash will ask for confirmation before taking any action which cannot be undone. For instance, emptying the Trashcan or overwriting an existing target during restore-from-Trashcan operations. This protects you from any accidental data destruction. However, IF YOU ARE SURE that you want to perform an action which cannot be reversed, you can use the 'no-confirm' option to disable confirmations. This option is useful if cTrash is executed from within a script file, or is invoked from within another application. The 'no-confirm' option does not apply to interactive operations such as interactive restoration (see 'R' option) or interactive removal (see 'E' option). #### Examples: Empty the Trashcan: ------------------- ctrash -e --no-confirm Permanently delete source items: -------------------------------- ctrash -td --no-confirm source1.cpp sourc2.cpp source3.hpp On Restore, overwrite any existing targets: ------------------------------------------- ctrash -r --no-confirm Please also see 'silent' option, which disables both confirmations, AND all output to the display. ––remove=[DAYS | HOURS | today] Remove items from trash based on delete date. Delete items from the Trashcan based on when they were moved to the trash. #### Arguments are: • DAYS: Delete items which have been in the Trashcan for at least the specified number of days. Range for DAYS: 1 through 366 days i.e. one(1) day through one(1) year, inclusive. Note that DAYS is expressed as a positive integer value. Example: ctrash --remove=14 • HOURS: Delete items which have been in the Trashcan for no more than the specified number of hours. Range for HOURS: -1 through -24 hours i.e. one(1) through 24 hours, inclusive. Note that HOURS is expressed as a negative integer value. Example: ctrash --remove=-12 • today: Delete items which were placed in the Trashcan on or after 00:00:00 (midnight), system local time, today. Example: ctrash --remove=today Note that the local time is rounded to the next whole minute for calculating the midnight timestamp, so the timestamp used for the comparison will be in the range of 23:59:01 to 00:00:00. Example: delete Trashcan items at least 7 days old (with verbose output): ======================================= Invocation: ----------- ctrash --remove=7 --verbose Interactive Output: ------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- cTrash.o (2015-09-11 14:08:26) cTrashCan.o (2015-09-11 14:08:26) cTrashFile.o (2015-09-11 14:08:26) gString.o (2015-09-11 14:08:26) Deleting 4 items (4 files and 177.7K bytes) from Trashcan. This operation cannot be undone. continue? (y/n): _ Your response: -------------- y (ENTER) Summary Output: --------------- cTrash.o (deleted) cTrashCan.o (deleted) cTrashFile.o (deleted) gString.o (deleted) 4 items (4 files) deleted from Trashcan. 177.7K bytes of disk space recovered. Note that because this operation cannot be reversed, the default is to prompt for confirmation before deleting the data. To disable this confirmation, see 'no-confirm' option. If desired, you can automatically delete stale data from the Trashcan every time you logout. To do this, add a cTrash command to your '~/.bash_logout' or whatever logout script your system uses. Example: Delete Trashcan items at least 30 days old: ---------------------------------------------------- ctrash --remove=30 --silent  To delete all data from the Trashcan, see 'e' option, above. To selectively delete Trashcan items, see 'E' option, above. ––sort=OPTION Specify the sort option for display of item lists. Specify how lists of items will be sorted for display. The sort option may be used to place the most interesting items near the bottom of the list, so there will be less need to scroll backward to find the desired item. The sort option takes one argument in the form: ctrash --sort=OPTION The OPTION token is one of the following, where ’ascending’ indicates that the list is sorted from low-to-high, and ’descending’ indicates that the list is sorted from high-to-low. • d sort by deletion date, ascending (default) • D sort by deletion date, descending • s sort by item size (bytes), ascending • S sort by item size (bytes), descending • n sort by item name, ascending • N sort by item name, descending Note on alphabetical sorts: a) sort is by original item name b) sort is case sensitive c) sort occurs according to the rules of the locale specified in the console environment. Example: Sort detailed statistics report by item size (low-to high): ctrash -S --sort=s The selected sort option applies to: • '-S' option: detailed statistics report • '-R' option: interactive selection of items to be restored from the Trashcan, • '-E' option: interactive selection of items to be deleted from the Trashcan, • '--verbose' option: detailed intermediate lists displayed during various operations ––file-list=LIST Specify a file with names of items for Trashcan. Specify a plain-text file containing a list of of items to be moved to the Trashcan. Replace 'LIST' with the name of the file. In a typical operation, only a few items will be moved to the Trashcan, and the names of those items can be specified directly on the command line; however, it is sometimes useful to specify a list of several items. • if there are a large number of items to be moved • if items are located in several different places • if you often send the same group of items to the Trashcan Note that items may be specified directly on the command line in addition to the items in the list specified using the '--file-list' option. As with the '-t' option above, items in the list file may be specified by relative path, absolute path, or by using environment-variable substitution. Unlike items specified directly on the command line, wildcard characters ('*' and '.') in item names are not expanded. A line which begins with a hash mark '#' is interpreted as a comment and is ignored. Blank lines are also ignored. Example List File ----------------- # For testing --file-list command # Non-empty directory ../ct_test_data/Abc_Dir ~/Photos/phone_pics/selfie/Selfie71.jpg${HOME}/Documents/ct_doc_notes.odt ../../tmp/libxcb-1.11.tar.bz2 cTrash.o cTrashFile.o cTrashCan.o

––alt-target=TARGET Specify an alternate path for restore.

Specify an alternate target for restoring item(s) from the Trashcan.
'TARGET' must be the path of an existing directory.

Exception: If exactly one(1) item is to be restored, you may specify an alternate target directory (as above), OR you may specify a full alternate path/filename for the restoration.

Examples: --------- Interactively restore an item or items from the Trashcan to indicated directory: ctrash -R --alt-target='~/Documents/backup_dir' Restore the most-recently-deleted item using an alternate path/filename specification: ctrash -r --alt-target='./oldsource.cpp'

Note that if the restore operation detects an existing file that will be overwritten, then the existing file must have the same file type as the item being restored.

As with all cTrash operations, protected data will not be modified or overwritten, regardless of its file type.

––trash-path=PATH Specify an alternate Trashcan path.

Specify an alternate location to search for the Trashcan directory.

By default, the user’s local Trashcan is used:
~/.local/share/Trash

Use this option to specify an alternate location for sending items to the Trashcan, for restoring items from the Trashcan and for Trashcan statistics reporting.

• 'PATH' must indicate an existing directory name.
• User must have read/write/execute permission for the specified directory.
• If the required subdirectories ('files' and 'info') do not exist in the specified directory, then they will be created. See see Tech Notes for more information on the Trashcan directory structure.

––delete Bypass the Trashcan and permanently delete source items.

cTrash is designed to provisionally delete files and directory trees by moving them to the Trashcan. Sometimes, however, you may be sure that you no longer want a particular item or items on your system. In this case, you would want to permanently delete that item, rather than storing it in the Trashcan.

The '--delete' or '-d' option instructs cTrash to immediately delete (unlink) the item(s), bypassing the Trashcan entirely and permanently removing the item(s) from your system.

This operation cannot be undone.

Note that because this operation cannot be reversed, the default is to prompt for confirmation before deleting the data. To disable this confirmation, see 'no-confirm' option.

Example: ======== Invocation: ----------- ctrash -d Old_Girlfriend_Photos Interactive Output: ------------------- ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- CAUTION: You are about to permanently remove 1 items (280 files) from your system. This operation cannot be undone. Delete files? (y/n): _ Your response: -------------- y (ENTER) Summary Output: --------------- OK: 1 items (280 files) permanently deleted.

Security Note: When files are ’unlinked’, the index (inode) record is deleted, returning the disk space to the system for reallocation. However, the data that make up that item are still physically written on the disk media. Until the space has been reallocated to another file, a sophisticated recovery program may be able to recover all or part of that data.
If you are working with sensitive data, you should use a disk wiping application to overwrite the physical data several times in order to completely destroy it.
Securely deleting data is actually even more complex than this. See the documentation for the coreutils ’ln’ command for a discussion of multiple ’hard links’ to a single file.

––rm-emulate Emulate support for 'rm' command options.

This option provides partial compatibility with the 'rm' (remove-file) console command.

Important Note: The '--rm-emulate' option must be the first argument following the 'ctrash' command, and all options which follow will be interpreted as ’rm’ options. cTrash standard-mode options will not be recognized when in 'rm' compatibility mode.

Compatibility mode affects only operations which move source items to the Trashcan. 'rm' compatibility mode has no effect on other cTrash options.

#### Implementation

The cTrash ’rm’ compatibility mode is not fully symmetrical with the ’rm’ command itself. There is a huge conceptual difference between deleting data and sending data to the Trashcan:

1. The data will still exist, just somewhere else, on the same or a different filesystem.
2. Source data for ’rm’ can be of any size because it is going away; however, source data for cTrash must fit into the freespace on the filesystem that contains the Trashcan.
3. Some 'rm' options are impractical or make no sense for provisionally-deleted data.

#### cTrash compared with ‘rm’

• 'rm' will attempt to remove files of any file type, which is great if you are intentionally wiping out your system, but is truly brain-dead for everyday work.
• cTrash operates only on items of the supported file types: regular files, directories, FIFOs and symbolic links.

• 'rm' will override write-protection with user permission.
• cTrash will never override protection on items or their contents.

• 'rm' asks for preconfirm ('-I' option) only if four(4) or more source items are specified.
• cTrash always preconfirms, when requested, without regard to item count.

• 'rm' knows only the user’s default Trashcan, so no alternate Trashcan directories may be specified.
• cTrash, when in emulation mode, also uses only the default Trashcan.

• 'rm' isn’t nearly so careful as cTrash about data protection. In addition, ’rm’ doesn’t have to worry about the user trying to send the Trashcan or the root directory to the trash.
• cTrash reports such an error as a "general protection error". If you encounter this error message and want more specific information, please run cTrash in standard (non-emulation) mode for full diagnostics.

• 'rm' returns a zero (0) value on total success, and returns a decimal 255 (an 8-bit ’-1’) if partial or total operation failure.
• cTrash also returns zero (0) on total success, but because we are no longer running on Z80(tm), S100-bus platforms, cTrash returns an integer-width ’-1’ on partial or total operation failure.

• 'rm' prompts for confirmation using the messages:
rm: remove regular file 'fname'? _
rm: remove fifo 'fname'? _
rm: remove symbolic link 'fname'? _
rm: remove directory 'dname'? _          (for empty directories)
rm: descend into directory 'dname'? _    (for non-empty directories)

• cTrash prompts for confirmation using these same messages; however, cTrash will exit after pretest for unsupported file types.

• 'rm', while in verbose mode and deleting a non-empty directory, reports deletion of each file contained in the base directory, and finally reports deletion of the base directory itself.
• cTrash finds this to be unnecessarily messy and un-helpful. For a much cleaner interface, cTrash reports only the deletion of the base directory along with the total number of files it contained.

• 'rm', relies on the shell program to resolve the target path for each item to be removed.
• cTrash takes a more controlled approach by fully decoding the path/filename specification for each target.

Editorial: Rubin, MacKenzie, Stallman, and Meyering wrote the 'rm' utility, which twenty years ago and was considered a cutting-edge hack for use only by experts. Linux is no longer just a hacker’s paradise. Contemporary Linux users are not necessarily experts; they are real people who deserve user friendliness and realistic feedback. For these reasons, 'rm' emulation is the wise choice for newbies and Liberal Arts majors, as well as for skilled hackers who occasionally work past the point of exhaustion (you know who you are :). In short,'rm' emulation is for everyone.

#### Using ‘rm’ emulation mode

If you want to replace ‘rm’ with a safe way to delete files and directory trees, you can alias ‘rm’ as:

alias rm=ctrash '--rm-emulate'.

#### Description of options

All 'rm' command-line options are recognized, and are implemented where practical. If emulation of an option is not practical (or is impossible), then the option will be ignored. Descriptions for each 'rm' option, and the way cTrash handles them are given below.

As of 'rm' version 8.21, the valid options are:

• --force, -f
"ignore nonexistent files and arguments, never prompt"

Never prompt for user confirmation, even when errors are detected.
cTrash equivalent: --no-confirm

This option masks the interactive options, below, if specified.

Note that cTrash (unlike ’rm’) will never ignore invalid option syntax, nor source files which were specified, but not found.

• -i
"prompt for every removal"

See '--interactive=WHEN' option, below.

• -I
"prompt once before removing more than three files, or when removing recursively"

See '--interactive=WHEN' option, below.

• --interactive=WHEN
"prompt according to WHEN" where ’WHEN’ is one of the following:
'never' (cTrash equivalent: '--no-confirm') Never prompt for user confirmation. 'once' (cTrash equivalent: '--preconfirm') (same as '-I' option, above) Prompt for user confirmation once before moving all specified items to the Trashcan. 'always' (or no argument) (cTrash equivalent: no equivalent) (same as '-i' option, above) Prompt for user confirmation for each item to be moved to the Trashcan.
• --one-file-system
"when removing a hierarchy recursively, skip any directory that is on a file system different from that of the corresponding command line argument"

cTrash recognizes but ignores this option.
cTrash never crosses filesystem boundaries while moving a directory tree to the Trashcan. For each directory item specified, ALL its contents must be on the same filesystem as the base directory, or NONE of the data for that item will be moved.

• --no-preserve-root
• --preserve-root
cTrash recognizes but ignores these two options. It is not possible to move '/' i.e. the root directory to another location.
• --recursive, -r, -R --dir, -d
"remove empty directories" ('--dir', '-d')
"remove directories and their contents recursively" ('--recursive', '-r', '-R')

In cTrash standard mode, directory items, whether empty or containing additional data, are processed as normal items which are always recursively moved to the Trashcan.

In 'rm' emulation mode, the '--recursive' and '--dir' options (and their short equivalents) place restrictions on the way in which directory items are handled.

1. By default directory items, if specified, are not processed.
2. If the '--dir' option is specified, then empty directories are processed as normal items. Non-empty directories will not be processed.
3. If the '--recursive' option is specified, then all directories are recursively processed as normal items. ('--dir' option is ignored.)

CAUTION: The total size of a recursive move may exceed the freespace on the target filesystem, so be aware of the size of recursive operations.

• --verbose, -v
"explain what is being done"

Verbose output provides more information on the operation being performed, specifically it verifies the success of an operation.

Emulation-mode verbose output is significantly different from (and less verbose than) cTrash standard-mode verbose output.

• --help
• --version
These options do not apply to 'rm' emulation. The equivalent cTrash options are used.

––stat-cols=COLCOUNT Specify maximum width of display output line.

Specify the maximum number of display columns per display line. This options helps to beautify formatting of display output. This option has no effect on processing of items, only on the way results are reported.

'COLCOUNT' must be an integer value between 80 and 512, inclusive.

By default, display output for path/filename specifications, statistics reporting and other output is optimized for a 132-column terminal window width.

Example: Display detailed statistics for the current contents of the Trashcan, optimized for an 80-column terminal window.

ctrash -S --stat-cols=80

Path/filename specifications are compressed as necessary to fit into the specified width. For example, a full path/filename specification might be reported as:
/home/sam/Documents/Teaching/CS_Lessons/CS1352/2015_Fall/BidirectionalSocket.pdf

The same report compressed for an 80-column terminal window would be:
/home/sam/Documents/Teaching/CS_Lessons/CS1352/.../BidirectionalSocket.pdf

––help Display cTrash command-line help.

Command-line Help. Display a brief summary of command-line usage and options. (overrides everything on command line except '--version')

––version Report cTrash version number.

Display the cTrash version number and copyright information. (overrides everything else on command line)

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## Building from Source

### Tools

The cTrash utility is written in C++ and is built with the GNU C++ compiler and linker. No additional link libraries or third-party tools are needed.

• GCC (G++) version 4.8.0 and above

### Compiling

cTrash is compiled using the GNU/G++ compiler which is invoked through the ’gmake’ (’make’) utility. The compile and linking instructions are contained in the file named ’Makefile’.

Example: gmake clean gmake

### Build Options

No optional builds are currently defined.

Planned for future releases: — static build for 32-bit and 64-bit Wintel systems — build as a link library for inclusion in other applications — graphic-text application using the NcDialog (ncursesw) library

### Testing the Build

To test the build, invoke with a request for the cTrash version number. You should get something similar to the following:

./ctrash --version ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

To test whether your system’s user local Trashcan is in the default location, invoke with a request for summary statistics. This will list a summary of the Trashcan’s current contents, or if the Trashcan is not in the default location, an error message will be displayed.

./ctrash -s ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- Trashcan Summary: ------------------------------------------------ LOCATION: /home/sam/.local/share/Trash ITEMS: 15 FILES: 23 TOTAL SIZE: 1.063M SIZE ON DISK: 1.178M FS FREESPACE: 249.1G ** OR ** ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- ERROR: Trashcan directory not found or improperly configured. '/home/sam/.local/share/Trash' For command-line options: 'ctrash --help'

 Important Note: If your user local Trashcan is not in the default location, you can easily find it. In a terminal window, go to the top of your HOME directory and use the ’find’ command: cd find -name ’*Trash’ You can locate other Trashcan directories on your system: cd / sudo find -name ’*Trash’

### Installation

For the cTrash utility to be visible throughout your system, you will need to copy the ’ctrash’ binary file to a directory on your execution path.

To see your execution path, type: echo $PATH. [cTrash]$ echo $PATH /usr/local/bin:/usr/bin:/bin:/usr/local/sbin: /usr/sbin:/home/sam/.local/bin:/home/sam/bin  The directories searched for binaries are separated by the colon ':' character. Generally, it is recommended that you choose the last entry in the list because that directory belong only to you. EXAMPLE: cp --preserve ctrash /home/sam/bin/. You may also want to use cTrash as a replacement for the ’rm’ command. To do this, create an ’alias’ which masks the ’rm’ command. alias rm=ctrash Or if you routinely use options with the ‘rm’ command, alias with ‘rm’ compatibility mode. Please see Invoking for more information on ‘rm’ compatibility mode. alias rm='ctrash --rm-emulate' Test your alias, and when it works satisfactorily, write your alias command into your '~/.bashrc' or whatever login script your system uses. Then logout and back in again and check whether your alias has been generated: alias -p Typical login scripts for GNU/Linux are:${HOME}/.bashrc # local user /root/.bashrc # root user /etc/bashrc # all users

To override an existing alias and execute the hidden command directly, use the backslash character before the command:
Example: \rm --help
This will display the actual 'rm' help, rather than the cTrash help.

Note on temporary files: cTrash creates various temporary files during execution. cTrash queries the system for the directory where temporary files are to be created. If the specified directory cannot be found, then cTrash cannot move files to and from the Trashcan, and a diagnostic message will be displayed:

ctrash v:0.0.06 (c)2015-2020 The Software Samurai ------------------------------------------------- ERROR: Directory for creating temporary file is inaccessible.

For more information on temporary files, please see the documentation for the 'tmpnam_r' C-language function or the coreutils 'mktemp' utility..

#### Installing the Documentation

Documentation for cTrash is provided in both Texinfo (info) format and HTML format.

To view the HTML-format documentation, navigate to:
cTrash/Texinfo
then load the 'ctrash.html' document into your favorite browser. Note that the 'infodoc-styles.css' CSS style definition file must be in the same directory as the HTML document.

To view the Texinfo (info) documentation, navigate to:
cTrash/Texinfo
then view the documentation using the following command:
info -f ctrash.info

Follow these steps to install the cTrash documentation into the ’info’ database.

1. Note that installing the documentation is not necessary, but is recommended. Not only is it convenient to have the documentation always available, but it is a useful skill for when you begin installing documentation for your own applications!
2. Adding an ’info’ document to the info-reader database (or removing a document from the database) is easy, but it does require ’SUPERUSER’ (’root’) user privilege. If this makes you nervous, please make a backup copy of the ’dir’ (info directory) file before modifying it.
3. Open a terminal window.
4. Navigate to the directory which contains the ’ctrash.info’ documentation.
Example: cd ~/MySoftware/cTrash/Texinfo (substitute your actual installation path)
5. Locate the master Info system directory file: ’dir’.
For local users, this is typically:
/usr/local/share/info/dir

For global system users, this is typically:
/usr/share/info/dir

6. Copy the document to the directory where you found the info ’dir’ file.
Example: sudo cp --preserve=timestamps ctrash.info /usr/local/share/info/. (substitute the actual path to the directory containing the 'dir' file) Enter your password when prompted.
7. Navigate to the Info target directory.
cd /usr/local/share/info
8. Verify that the document was copied correctly. ls -l ctrash.info
sudo install-info --dir-file=dir --info-file=ctrash.info --name=’Console Trashcan’ --debug Note that this is a single command, typed all on one line even though it may look strange as printed here. Enter your password when prompted.
10. Verify the install.
Type the following command: info

This will open the top-level menu of the Info system.
Verify that your new entry is beautifully displayed and that the new Info document is accessible:

First, press the forward-slash key ’/’ (search)
Then, type: Console Trashcan (and press ENTER)
The highlight should now be on the menu entry.
Press ENTER (RET) key again, and verify that the main page of the cTrash documentation is displayed.
Then, exit the Info system: ’q’ (quit).

11. If the menu item is not present OR if the new Info document is not accessible, then try the installation again.

If you want to remove the menu entry, use the command:

sudo install-info --dir-file=dir --info-file=ctrash.info --name=’Console Trashcan’ --remove --debug Again, this is a single command, typed all on one line. Enter your password when prompted.

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## Tech Notes

### Where Is the Trashcan?

Historically, a UNIX/Linux system’s Trashcan could be in any convenient location, and there could be multiple Trashcans defined throughout the filesystem tree, depending upon who is sending data to the trash, and where they are located (user, superuser, local, remote).

Today, various groups such as FreeDesktop.org, GNU.org, Ubuntu.com and others agree that the local user’s Trashcan should be located at:

~/.local/share/Trash

This is the Trashcan located on your personal, home path.

Example: /home/sam/.local/share/Trash

Additional trash directories may exist for administrative, or security reasons, but unless you are an Admin weenie, there is little need to be concerned about them. However, for the Admin folks, cTrash is flexible enough that you can specify any Trashcan in the system as your target.

### What the Trashcan Looks Like

There is nothing magical about the system’s Trashcan directory structure, and in fact, considering how powerful and useful it is, the Trashcan is quite a simple device. The only potential source of trouble is that it requires all applications to play nicely together, and to not corrupt each other’s data.

Specifically, each item (file or directory) sent to the Trashcan must have a unique name and information about the original location of the item in the filesystem.

The Trashcan consists of the following directory structure:

┌─ files Trash/──┤ └─ info

### How the Trashcan Works

Items sent to the Trashcan are renamed if necessary, following a specific, serialization algorithm, and moved to the 'Trash/files' subdirectory.

An information file describing the item is created in the 'Trash/info' subdirectory with the same name as the item, but with the '.trashinfo' filename extension appended. (This is a plain text file.)

Example of a '.trashinfo' description file. There are three(3) lines in this file, the header, the original path/filename and the date the item was deleted.

[Trash Info] Path=/home/sam/Software/cTrash/install/cTrash/Makefile DeletionDate=2015-07-29T11:18:31

When the Trashcan is emptied, both the item and its ’.trashinfo’ description file are deleted (’unlink’d) from the filesystem.

When an item is restored from the Trashcan, the ’.trashinfo’ description is used to return the item to its original location, with its original name and timestamp, then after the restoration is complete, the ’.trashinfo’ file is deleted.

### Example Trashcan Sequence

During development and testing, we sent a large number of items to the system Trashcan. This is an example of three(3) iterations of sending our test data to the Trashcan. The Trashcan is initially empty.

The test data consist of a subdirectory, ’Abc’ which contains 31 additional files and directory names, as well as the four(4) object files created during the cTrash build: ’cTrash.o’, ’cTrashFile.o’, ’cTrashCan.o’ and ’gString.o’.

Each time, the invocation is:

./ctrash Abc *.o

After the first invocation, the Trashcan contains the following.
Note that because there were no conflicts with existing data, the target items have the same names as the source items.
(The contents of the subdirectory always retain their original names.)

        ┌─ files/
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:40 Abc
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:39 cTrash.o
│    -rw-rw-r--. 1 1000 1000 25216 Sep  6 00:39 cTrashCan.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  5 10:34 cTrashFile.o
│    -rw-rw-r--. 1 1000 1000 56080 Aug 23 00:12 gString.o
Trash/──┤
├─ info/
│    -rw-rw-r--. 1 1000 1000  99 Sep  6 00:40 Abc.trashinfo
│    -rw-rw-r--. 1 1000 1000 104 Sep  6 00:40 cTrash.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:40 cTrashCan.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 108 Sep  6 00:40 cTrashFile.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 105 Sep  6 00:40 gString.o.trashinfo
└───────


A new copy of the test data is then created in our source directory.
After the second invocation, the Trashcan contains the following.
Note that the second set of items has been renamed with the addition of '.2' before the filename extension to avoid conflict with the existing data.

        ┌─ files/
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:40 Abc
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:49 Abc.2
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:39 cTrash.o
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:45 cTrash.2.o
│    -rw-rw-r--. 1 1000 1000 25216 Sep  6 00:39 cTrashCan.o
│    -rw-rw-r--. 1 1000 1000 25336 Sep  6 00:51 cTrashCan.2.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  5 10:34 cTrashFile.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  6 00:45 cTrashFile.2.o
│    -rw-rw-r--. 1 1000 1000 56080 Aug 23 00:12 gString.o
│    -rw-rw-r--. 1 1000 1000 56080 Sep  6 00:45 gString.2.o
Trash/──┤
├─ info/
│    -rw-rw-r--. 1 1000 1000  99 Sep  6 00:40 Abc.trashinfo
│    -rw-rw-r--. 1 1000 1000 101 Sep  6 00:54 Abc.2.trashinfo
│    -rw-rw-r--. 1 1000 1000 104 Sep  6 00:40 cTrash.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 106 Sep  6 00:54 cTrash.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:40 cTrashCan.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 109 Sep  6 00:54 cTrashCan.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 108 Sep  6 00:40 cTrashFile.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 110 Sep  6 00:54 cTrashFile.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 105 Sep  6 00:40 gString.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:54 gString.2.o.trashinfo
└───────


A new copy of the test data is then created in our source directory.
After the third invocation, the Trashcan contains the following. Note that the filename serialization has advanced to '.3'.

        ┌─ files/
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:40 Abc
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:49 Abc.2
│    drwxrwxr-x. 4 1000 1000  4096 Sep  6 00:56 Abc.3
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:39 cTrash.o
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:45 cTrash.2.o
│    -rw-rw-r--. 1 1000 1000 59760 Sep  6 00:56 cTrash.3.o
│    -rw-rw-r--. 1 1000 1000 25216 Sep  6 00:39 cTrashCan.o
│    -rw-rw-r--. 1 1000 1000 25336 Sep  6 00:51 cTrashCan.2.o
│    -rw-rw-r--. 1 1000 1000 25336 Sep  6 00:56 cTrashCan.3.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  5 10:34 cTrashFile.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  6 00:45 cTrashFile.2.o
│    -rw-rw-r--. 1 1000 1000 35088 Sep  6 00:56 cTrashFile.3.o
│    -rw-rw-r--. 1 1000 1000 56080 Aug 23 00:12 gString.o
│    -rw-rw-r--. 1 1000 1000 56080 Sep  6 00:45 gString.2.o
│    -rw-rw-r--. 1 1000 1000 56080 Sep  6 00:56 gString.3.o
Trash/──┤
├─ info/
│    -rw-rw-r--. 1 1000 1000  99 Sep  6 00:40 Abc.trashinfo
│    -rw-rw-r--. 1 1000 1000 101 Sep  6 00:54 Abc.2.trashinfo
│    -rw-rw-r--. 1 1000 1000 101 Sep  6 00:56 Abc.3.trashinfo
│    -rw-rw-r--. 1 1000 1000 104 Sep  6 00:40 cTrash.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 106 Sep  6 00:54 cTrash.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 106 Sep  6 00:56 cTrash.3.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:40 cTrashCan.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 109 Sep  6 00:54 cTrashCan.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 109 Sep  6 00:56 cTrashCan.3.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 108 Sep  6 00:40 cTrashFile.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 110 Sep  6 00:54 cTrashFile.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 110 Sep  6 00:56 cTrashFile.3.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 105 Sep  6 00:40 gString.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:54 gString.2.o.trashinfo
│    -rw-rw-r--. 1 1000 1000 107 Sep  6 00:56 gString.3.o.trashinfo
└───────


Using the filename serialization demonstrated, any reasonable number of items with the same original name may be sent to the Trashcan without loss of data. However, it is generally good practice to empty the Trashcan every week or two to recover your disk space.

If you are working with sensitive data, it is recommended that you empty your Trashcan every time you logout. To do this, add the following line to your '~/.bash_logout' or whatever logout script your system uses.

ctrash -e --silent

#### A Note on gString

Text formatting and analysis within the cTrash application is performed by the gString class. gString is similar to the Glib::ustr() class of the GTK toolkit, but is much simpler, smaller and faster.
gString is written by the author of cTrash, and is available (with full documentation) from the author’s website either as part of the NcDialogAPI, or as a stand-alone package. See By the Same Author.

Next: , Previous: , Up: Top   [Contents][Index]

## Technical Support

Please Note: All trademarks and service marks mentioned in this document are the entirely-too-proprietary property of their respective owners, and this author makes no representation of affiliation with or ownership of any of the damned things.

### Contact

cTrash (ctrash) binary, source code and associated Texinfo documentation were written and are maintained by: Mahlon R. Smith, The Software Samurai Beijing University of Technology on the web at: www.SoftwareSam.us For bugs, suggestions, periodic updates, or possible praise, please post a message to the author via website. The author wishes to thank everyone for their intelligent, kind and thoughtful responses. (ranters I can live without)

### History

Console warriors are the driving force behind the free-as-in-freedom software community, but their need for direct access to the system Trashcan, both as a stand-alone utility and to support the operation of other console applications was not being well served by the mainline Linux developers. For this reason, we offer cTrash to fill this gap in basic Linux functionality.

The basic algorithm used in cTrash was originally developed as the Trashcan management module of the author’s FileMangler (fmg) file-management utility (available as a separate download).

cTrash is a much simplified version of the FileMangler module, while retaining the full functionality of that code. While FileMangler uses a text-based graphical interface (ncurses), cTrash is a pure console (command-line) utility.

While Nautilus and other file-management GUIs are busy drawing pretty images on the screen, cTrash is actually getting the job done. Enjoy!

### By the Same Author

• NcDialog Application Programming Interface (API) library.
The NcDialog API forms the basis for most of our other software projects. It provides the application developer with the tools to create dialog-based console applications, without the need to learn anything about the complexities of the underlying ‘ncurses’ C-language library.

Console applications have always been the most efficient and easily-implemented of computer programs. What they lacked was a friendly and visually-pleasing user interface.

With the NcDialog API, console applications can now be used and understood by experts and novice users alike.

• FileMangler (fmg), is a compact, fast and flexible tool for handling all your file management needs.

FileMangler performs all basic file management tasks, as well as performing scheduled and ad-hoc file backup and synchronization activities.

FileMangler runs in a console window, and thus provides access to many system tools not available to a GUI application. FileMangler also provides full support for accessing the local Trashcan.

FileMangler is based on the NcDialog API, and thus will run in almost any GNU/Linux or UNIX terminal environment.

• Infodoc, post-processing and CSS style for HTML documents created by the Texinfo (makeinfo) utility. If you write documentation using the Texinfo/makeinfo documentation engine, AND if you care at all about what your documentation looks like, then you really do need the ‘infodoc-styles.css‘ definition file and the ‘idpp’ HTML post-processor.

The HTML version of this document was formatted using ‘idpp’ and is displayed using the ‘infodoc-styles.css‘ definition file. Many more examples are available on the author’s website.

• gString text internationalization tool.
gString implements a C++ class that may be integraged into any application for smooth and painless text formatting, and for converting between UTF-8 and ‘wchar_t’ (wide) character encoding.

The gString class is lightweight, consisting of one C++ source module and one header file. The gString class may be directly integrated into an application, or may be built as a link library.
The gString class is also embedded within the NcDialog API library (see above).

• Taggit (taggit) is a demonstration program written for students, or for anyone who wishes to create a console application with a multilingual user interface.

Conceptually, Taggit is an audio-file tag editor (metadata editor), and is album oriented rather than file oriented so that all audio files in an album may be edited simultaneously.

Taggit is not intended as a full-featured tag editor; for instance, Taggit does not access online databases of audio tag information. Taggit fully supports tag editing for two audio formats: MP3 and OGG/Vorbis.

The OGG/Vorbis I specification is supported for all text tags in '.ogg' and '.oga' audio files.

For MP3 audio files, all tag frames of the ID3v2.3 standard are supported, along with some features of ID3v2.4, such as support for UTF-8 text encoding which enables writing text tags in any language.

Taggit is implemented in four(4) user interface languages: Español (Spanish), Zhōngwén (中文) (Chinese, simplified), Tiếng Việt (Vietnamese) and English (U.S.). Additional user interface languages (both LTR and RTL) may be added with minimum effort.

• Source Profiler (srcprof) is a source code analysis tool for determining the ‘maintainability’ of source code modules.

‘srcprof’ can be used to profile source code for high-level languages such as C, C++ and Java, as well as various assembly languages and scripting languages such as Python, Perl and Ruby. For a complete list of currently-supported source languages, please see the Source Profiler documentation.

’srcprof’ can be used both as a productivity-measurement tool and as a tool for testing source code quality based on an evaluation of its ‘maintainability’.

Source Profiler is a console-based utility, which runs as either a pure, command-line utility, OR as a dialog application based on the NcDialog API.

• DVD Repair (dvdrep) is a utility for exploring the contents of a damaged DVD video disc and rescuing as much of the data as possible.

‘dvdrep’ can be used to rescue data from any non-encrypted DVD video source disc that is formatted using the Universal Disc Format (UDF) filesystem (as all commercially produced DVD movies are).

‘dvdrep’ takes a layered approach to the analysis of the source disc. A detailed log file is maintained for each step of the process in case manual intervention is needed at a later step.

DVD Repair is based on the NcDialog API, and thus will run in almost any GNU/Linux or UNIX terminal environment.

• WaylandCB, clipboard access for console applications.
Access to the system clipboard under the Wayland communications protocol, leveraging Sergey Bugaev’s "wl-clipboard" application suite.

WaylandCB is a simple C++ class definition which provides console applications with seemless access to the system clipboard.

• crcPlus (crcplus) is a reference model and demonstration program for implementating CRC (Cyclic Redundancy Check) data error detection. crcPlus provides a reliable reference algorithm for verifying the function of other CRC generators and decoders as well as providing the tools to build a fully customizable hash table (lookup table) for creating your own high-speed CRC generator.
• Various other Linux utilities designed as academic exercises are also available for student use. For example: interprocess communication pipes, FIFOs, sockets, shared memory blocks, multi-threading, the ’Sleeping Barber’ problem and so on.
These cannot be considered as production-worthy, but they demonstrate the concepts in simple terms.

Next: , Previous: , Up: Top   [Contents][Index]

The cTrash binary and source code are released under the GNU General Public License (GPL 3+), and the user documentation (this document) is released under the GNU Free Documentation License (FDL 1.3+):

Copyright © 2015-2020 Mahlon R. Smith, The Software Samurai This manual describes version 0.0.06 of ’ctrash’. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled  "GNU Free Documentation License".

Version 3, 29 June 2007

Copyright © 2007 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

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1. Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License; or
2. Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it; or
3. Prohibiting misrepresentation of the origin of that material, or requiring that modified versions of such material be marked in reasonable ways as different from the original version; or
4. Limiting the use for publicity purposes of names of licensors or authors of the material; or
5. Declining to grant rights under trademark law for use of some trade names, trademarks, or service marks; or
6. Requiring indemnification of licensors and authors of that material by anyone who conveys the material (or modified versions of it) with contractual assumptions of liability to the recipient, for any liability that these contractual assumptions directly impose on those licensors and authors.

All other non-permissive additional terms are considered “further restrictions” within the meaning of section 10. If the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term. If a license document contains a further restriction but permits relicensing or conveying under this License, you may add to a covered work material governed by the terms of that license document, provided that the further restriction does not survive such relicensing or conveying.

If you add terms to a covered work in accord with this section, you must place, in the relevant source files, a statement of the additional terms that apply to those files, or a notice indicating where to find the applicable terms.

Additional terms, permissive or non-permissive, may be stated in the form of a separately written license, or stated as exceptions; the above requirements apply either way.

9. Termination.

You may not propagate or modify a covered work except as expressly provided under this License. Any attempt otherwise to propagate or modify it is void, and will automatically terminate your rights under this License (including any patent licenses granted under the third paragraph of section 11).

However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, you do not qualify to receive new licenses for the same material under section 10.

10. Acceptance Not Required for Having Copies.

You are not required to accept this License in order to receive or run a copy of the Program. Ancillary propagation of a covered work occurring solely as a consequence of using peer-to-peer transmission to receive a copy likewise does not require acceptance. However, nothing other than this License grants you permission to propagate or modify any covered work. These actions infringe copyright if you do not accept this License. Therefore, by modifying or propagating a covered work, you indicate your acceptance of this License to do so.

11. Automatic Licensing of Downstream Recipients.

Each time you convey a covered work, the recipient automatically receives a license from the original licensors, to run, modify and propagate that work, subject to this License. You are not responsible for enforcing compliance by third parties with this License.

An “entity transaction” is a transaction transferring control of an organization, or substantially all assets of one, or subdividing an organization, or merging organizations. If propagation of a covered work results from an entity transaction, each party to that transaction who receives a copy of the work also receives whatever licenses to the work the party’s predecessor in interest had or could give under the previous paragraph, plus a right to possession of the Corresponding Source of the work from the predecessor in interest, if the predecessor has it or can get it with reasonable efforts.

You may not impose any further restrictions on the exercise of the rights granted or affirmed under this License. For example, you may not impose a license fee, royalty, or other charge for exercise of rights granted under this License, and you may not initiate litigation (including a cross-claim or counterclaim in a lawsuit) alleging that any patent claim is infringed by making, using, selling, offering for sale, or importing the Program or any portion of it.

12. Patents.

A “contributor” is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based. The work thus licensed is called the contributor’s “contributor version”.

A contributor’s “essential patent claims” are all patent claims owned or controlled by the contributor, whether already acquired or hereafter acquired, that would be infringed by some manner, permitted by this License, of making, using, or selling its contributor version, but do not include claims that would be infringed only as a consequence of further modification of the contributor version. For purposes of this definition, “control” includes the right to grant patent sublicenses in a manner consistent with the requirements of this License.

Each contributor grants you a non-exclusive, worldwide, royalty-free patent license under the contributor’s essential patent claims, to make, use, sell, offer for sale, import and otherwise run, modify and propagate the contents of its contributor version.

In the following three paragraphs, a “patent license” is any express agreement or commitment, however denominated, not to enforce a patent (such as an express permission to practice a patent or covenant not to sue for patent infringement). To “grant” such a patent license to a party means to make such an agreement or commitment not to enforce a patent against the party.

If you convey a covered work, knowingly relying on a patent license, and the Corresponding Source of the work is not available for anyone to copy, free of charge and under the terms of this License, through a publicly available network server or other readily accessible means, then you must either (1) cause the Corresponding Source to be so available, or (2) arrange to deprive yourself of the benefit of the patent license for this particular work, or (3) arrange, in a manner consistent with the requirements of this License, to extend the patent license to downstream recipients. “Knowingly relying” means you have actual knowledge that, but for the patent license, your conveying the covered work in a country, or your recipient’s use of the covered work in a country, would infringe one or more identifiable patents in that country that you have reason to believe are valid.

If, pursuant to or in connection with a single transaction or arrangement, you convey, or propagate by procuring conveyance of, a covered work, and grant a patent license to some of the parties receiving the covered work authorizing them to use, propagate, modify or convey a specific copy of the covered work, then the patent license you grant is automatically extended to all recipients of the covered work and works based on it.

A patent license is “discriminatory” if it does not include within the scope of its coverage, prohibits the exercise of, or is conditioned on the non-exercise of one or more of the rights that are specifically granted under this License. You may not convey a covered work if you are a party to an arrangement with a third party that is in the business of distributing software, under which you make payment to the third party based on the extent of your activity of conveying the work, and under which the third party grants, to any of the parties who would receive the covered work from you, a discriminatory patent license (a) in connection with copies of the covered work conveyed by you (or copies made from those copies), or (b) primarily for and in connection with specific products or compilations that contain the covered work, unless you entered into that arrangement, or that patent license was granted, prior to 28 March 2007.

Nothing in this License shall be construed as excluding or limiting any implied license or other defenses to infringement that may otherwise be available to you under applicable patent law.

13. No Surrender of Others’ Freedom.

If conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot convey a covered work so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not convey it at all. For example, if you agree to terms that obligate you to collect a royalty for further conveying from those to whom you convey the Program, the only way you could satisfy both those terms and this License would be to refrain entirely from conveying the Program.

14. Use with the GNU Affero General Public License.

Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such.

15. Revised Versions of this License.

The Free Software Foundation may publish revised and/or new versions of the GNU General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Program specifies that a certain numbered version of the GNU General Public License “or any later version” applies to it, you have the option of following the terms and conditions either of that numbered version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.

If the Program specifies that a proxy can decide which future versions of the GNU General Public License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Program.

16. Disclaimer of Warranty.

THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

17. Limitation of Liability.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

18. Interpretation of Sections 15 and 16.

If the disclaimer of warranty and limitation of liability provided above cannot be given local legal effect according to their terms, reviewing courts shall apply local law that most closely approximates an absolute waiver of all civil liability in connection with the Program, unless a warranty or assumption of liability accompanies a copy of the Program in return for a fee.

#### How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

one line to give the program's name and a brief idea of what it does. Copyright (C) year name of author This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Also add information on how to contact you by electronic and paper mail.

If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:

program Copyright (C) year name of author This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’. This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details.

The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program’s commands might be different; for a GUI interface, you would use an “about box”.

You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see https://www.gnu.org/licenses/.

The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read https://www.gnu.org/licenses/why-not-lgpl.html.

Previous: , Up: Copyright Notice   [Contents][Index]

Version 1.3, 3 November 2008

Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
1. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

2. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document’s overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not “Transparent” is called “Opaque”.

Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work’s title, preceding the beginning of the body of the text.

The “publisher” means any person or entity that distributes copies of the Document to the public.

A section “Entitled XYZ” means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as “Acknowledgements”, “Dedications”, “Endorsements”, or “History”.) To “Preserve the Title” of such a section when you modify the Document means that it remains a section “Entitled XYZ” according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

3. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

4. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

5. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

1. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
2. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
3. State on the Title page the name of the publisher of the Modified Version, as the publisher.
4. Preserve all the copyright notices of the Document.
6. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
8. Include an unaltered copy of this License.
9. Preserve the section Entitled “History”, Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
11. For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
13. Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
14. Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
15. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version’s license notice. These titles must be distinct from any other section titles.

You may add a section Entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

6. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled “History” in the various original documents, forming one section Entitled “History”; likewise combine any sections Entitled “Acknowledgements”, and any sections Entitled “Dedications”. You must delete all sections Entitled “Endorsements.”

7. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

8. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

9. TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

10. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.

11. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See https://www.gnu.org/licenses/.

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document.

12. RELICENSING

“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site.

“Incorporate” means to publish or republish a Document, in whole or in part, as part of another Document.

An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.

The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing.

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

Copyright (C) year your name. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License''.

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this:

with the Invariant Sections being list their titles, with the Front-Cover Texts being list, and with the Back-Cover Texts being list.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

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## Index

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