Table of Contents

1. Introduction
2. Common options

2.1 Backup options
2.2 Block size
2.3 Target directory
2.4 Trailing slashes
2.5 Standards conformance

3. Output of entire files

3.1 cat: Concatenate and write files
3.2 tac: Concatenate and write files in reverse
3.3 nl: Number lines and write files
3.4 od: Write files in octal or other formats

4. Formatting file contents

4.1 fmt: Reformat paragraph text
4.2 pr: Paginate or columnate files for printing
4.3 fold: Wrap input lines to fit in specified width

5. Output of parts of files

5.1 head: Output the first part of files
5.2 tail: Output the last part of files
5.3 split: Split a file into fixed-size pieces
5.4 csplit: Split a file into context-determined pieces

6. Summarizing files

6.1 wc: Print byte, word, and line counts
6.2 sum: Print checksum and block counts
6.3 cksum: Print CRC checksum and byte counts
6.4 md5sum: Print or check message-digests

7. Operating on sorted files

7.1 sort: Sort text files
7.2 uniq: Uniquify files
7.3 comm: Compare two sorted files line by line
7.4 tsort: Topological sort
7.5 tsort: Background
7.6 ptx: Produce permuted indexes

7.6.1 General options
7.6.2 Charset selection
7.6.3 Word selection and input processing
7.6.4 Output formatting
7.6.5 The GNU extensions to ptx

8. Operating on fields within a line

8.1 cut: Print selected parts of lines
8.2 paste: Merge lines of files
8.3 join: Join lines on a common field

9. Operating on characters

9.1 tr: Translate, squeeze, and/or delete characters

9.1.1 Specifying sets of characters
9.1.2 Translating
9.1.3 Squeezing repeats and deleting
9.1.4 Warning messages

9.2 expand: Convert tabs to spaces
9.3 unexpand: Convert spaces to tabs

10. Directory listing

10.1 ls: List directory contents

10.1.1 Which files are listed
10.1.2 What information is listed
10.1.3 Sorting the output
10.1.4 More details about version sort
10.1.5 General output formatting
10.1.6 Formatting file timestamps
10.1.7 Formatting the file names

10.2 dir: Briefly list directory contents
10.3 vdir: Verbosely list directory contents
10.4 dircolors: Color setup for ls

11. Basic operations

11.1 cp: Copy files and directories
11.2 dd: Convert and copy a file
11.3 install: Copy files and set attributes
11.4 mv: Move (rename) files
11.5 rm: Remove files or directories
11.6 shred: Remove files more securely

12. Special file types

12.1 link: Make a hard link via the link syscall
12.2 ln: Make links between files
12.3 mkdir: Make directories
12.4 mkfifo: Make FIFOs (named pipes)
12.5 mknod: Make block or character special files
12.6 rmdir: Remove empty directories
12.7 unlink: Remove files via the unlink syscall

13. Changing file attributes

13.1 chown: Change file owner and group
13.2 chgrp: Change group ownership
13.3 chmod: Change access permissions
13.4 touch: Change file timestamps

14. Disk usage

14.1 df: Report filesystem disk space usage
14.2 du: Estimate file space usage
14.3 stat: Report file or filesystem status
14.4 sync: Synchronize data on disk with memory

15. Printing text

15.1 echo: Print a line of text
15.2 printf: Format and print data
15.3 yes: Print a string until interrupted

16. Conditions

16.1 false: Do nothing, unsuccessfully
16.2 true: Do nothing, successfully
16.3 test: Check file types and compare values

16.3.1 File type tests
16.3.2 Access permission tests
16.3.3 File characteristic tests
16.3.4 String tests
16.3.5 Numeric tests
16.3.6 Connectives for test

16.4 expr: Evaluate expressions

16.4.1 String expressions
16.4.2 Numeric expressions
16.4.3 Relations for expr
16.4.4 Examples of using expr

17. Redirection

17.1 tee: Redirect output to multiple files

18. File name manipulation

18.1 basename: Strip directory and suffix from a file name
18.2 dirname: Strip non-directory suffix from a file name
18.3 pathchk: Check file name portability

19. Working context

19.1 pwd: Print working directory
19.2 stty: Print or change terminal characteristics

19.2.1 Control settings
19.2.2 Input settings
19.2.3 Output settings
19.2.4 Local settings
19.2.5 Combination settings
19.2.6 Special characters
19.2.7 Special settings

19.3 printenv: Print all or some environment variables
19.4 tty: Print file name of terminal on standard input

20. User information

20.1 id: Print real and effective uid and gid
20.2 logname: Print current login name
20.3 whoami: Print effective user id
20.4 groups: Print group names a user is in
20.5 users: Print login names of users currently logged in
20.6 who: Print who is currently logged in

21. System context

21.1 date: Print or set system date and time

21.1.1 Time directives
21.1.2 Date directives
21.1.3 Literal directives
21.1.4 Padding
21.1.5 Setting the time
21.1.6 Options for date
21.1.7 Examples of date

21.2 uname: Print system information
21.3 hostname: Print or set system name
21.4 hostid: Print numeric host identifier.

22. Modified command invocation

22.1 chroot: Run a command with a different root directory
22.2 env: Run a command in a modified environment
22.3 nice: Run a command with modified scheduling priority
22.4 nohup: Run a command immune to hangups
22.5 su: Run a command with substitute user and group id

23. Process control

23.1 kill: Send a signal to processes

24. Delaying

24.1 sleep: Delay for a specified time

25. Numeric operations

25.1 factor: Print prime factors
25.2 seq: Print numeric sequences

26. File permissions

26.1 Structure of File Permissions
26.2 Symbolic Modes

26.2.1 Setting Permissions
26.2.2 Copying Existing Permissions
26.2.3 Changing Special Permissions
26.2.4 Conditional Executability
26.2.5 Making Multiple Changes
26.2.6 The Umask and Protection

26.3 Numeric Modes

27. Date input formats

27.1 General date syntax
27.2 Calendar date items
27.3 Time of day items
27.4 Time zone items
27.5 Day of week items
27.6 Relative items in date strings
27.7 Pure numbers in date strings
27.8 Authors of getdate

28. Opening the Software Toolbox

Toolbox Introduction
I/O Redirection
The who Command
The cut Command
The sort Command
The uniq Command
Putting the Tools Together

A. GNU Free Documentation License

ADDENDUM: How to use this License for your documents

Index