Gnu/coreutils/index

GNU Coreutils

Short Table of Contents

• 1 Introduction
• 2 Common options
• 3 Output of entire files
• 4 Formatting file contents
• 5 Output of parts of files
• 6 Summarizing files
• 7 Operating on sorted files
• 8 Operating on fields
• 9 Operating on characters
• 10 Directory listing
• 11 Basic operations
• 12 Special file types
• 13 Changing file attributes
• 14 Disk usage
• 15 Printing text
• 16 Conditions
• 17 Redirection
• 18 File name manipulation
• 19 Working context
• 20 User information
• 21 System context
• 22 SELinux context
• 23 Modified command invocation
• 24 Process control
• 25 Delaying
• 26 Numeric operations
• 27 File permissions
• 28 File timestamps
• 29 Date input formats
• 30 Version sort ordering
• 31 Opening the Software Toolbox
• Appendix A GNU Free Documentation License
• Index

Table of Contents

• 1 Introduction
• 2 Common options
  • 2.1 Exit status
  • 2.2 Backup options
  • 2.3 Block size
  • 2.4 Floating point numbers
  • 2.5 Signal specifications
  • 2.6 chown, chgrp, chroot, id: Disambiguating user names and IDs
  • 2.7 Sources of random data
  • 2.8 Target directory
  • 2.9 Trailing slashes
  • 2.10 Traversing symlinks
  • 2.11 Treating / specially
  • 2.12 Special built-in utilities
  • 2.13 Standards conformance
  • 2.14 coreutils: Multi-call program
• 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
  • 3.5 base32: Transform data into printable data
  • 3.6 base64: Transform data into printable data
  • 3.7 basenc: Transform data into printable data
• 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 pieces.
  • 5.4 csplit: Split a file into context-determined pieces
• 6 Summarizing files
  • 6.1 wc: Print newline, word, and byte counts
  • 6.2 sum: Print checksum and block counts
  • 6.3 cksum: Print CRC checksum and byte counts
  • 6.4 b2sum: Print or check BLAKE2 digests
  • 6.5 md5sum: Print or check MD5 digests
  • 6.6 sha1sum: Print or check SHA-1 digests
  • 6.7 sha2 utilities: Print or check SHA-2 digests
• 7 Operating on sorted files
  • 7.1 sort: Sort text files
  • 7.2 shuf: Shuffling text
  • 7.3 uniq: Uniquify files
  • 7.4 comm: Compare two sorted files line by line
  • 7.5 ptx: Produce permuted indexes
    • 7.5.1 General options
    • 7.5.2 Charset selection
    • 7.5.3 Word selection and input processing
    • 7.5.4 Output formatting
    • 7.5.5 The GNU extensions to ptx
  • 7.6 tsort: Topological sort
    • 7.6.1 tsort: Background
• 8 Operating on fields
  • 8.1 cut: Print selected parts of lines
  • 8.2 paste: Merge lines of files
  • 8.3 join: Join lines on a common field
    • 8.3.1 General options
    • 8.3.2 Pre-sorting
    • 8.3.3 Working with fields
    • 8.3.4 Controlling join’s field matching
    • 8.3.5 Header lines
    • 8.3.6 Union, Intersection and Difference of files
• 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
  • 9.2 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 General output formatting
    • 10.1.5 Formatting file timestamps
    • 10.1.6 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 readlink: Print value of a symlink or canonical file name
  • 12.7 rmdir: Remove empty directories
  • 12.8 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 file system disk space usage
  • 14.2 du: Estimate file space usage
  • 14.3 stat: Report file or file system status
  • 14.4 sync: Synchronize cached writes to persistent storage
  • 14.5 truncate: Shrink or extend the size of a file
• 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 or processes
• 18 File name manipulation
  • 18.1 basename: Strip directory and suffix from a file name
  • 18.2 dirname: Strip last file name component
  • 18.3 pathchk: Check file name validity and portability
  • 18.4 mktemp: Create temporary file or directory
  • 18.5 realpath: Print the resolved file name.
    • 18.5.1 Realpath usage examples
• 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 user identity
  • 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 conversion specifiers
    • 21.1.2 Date conversion specifiers
    • 21.1.3 Literal conversion specifiers
    • 21.1.4 Padding and other flags
    • 21.1.5 Setting the time
    • 21.1.6 Options for date
    • 21.1.7 Examples of date
  • 21.2 arch: Print machine hardware name
  • 21.3 nproc: Print the number of available processors
  • 21.4 uname: Print system information
  • 21.5 hostname: Print or set system name
  • 21.6 hostid: Print numeric host identifier
  • 21.7 uptime: Print system uptime and load
• 22 SELinux context
  • 22.1 chcon: Change SELinux context of file
  • 22.2 runcon: Run a command in specified SELinux context
• 23 Modified command invocation
  • 23.1 chroot: Run a command with a different root directory
  • 23.2 env: Run a command in a modified environment
    • 23.2.1 General options
    • 23.2.2 -S/--split-string usage in scripts
      • Testing and troubleshooting
    • 23.2.3 -S/--split-string syntax
      • Splitting arguments by whitespace
      • Escape sequences
      • Comments
      • Environment variable expansion
  • 23.3 nice: Run a command with modified niceness
  • 23.4 nohup: Run a command immune to hangups
  • 23.5 stdbuf: Run a command with modified I/O stream buffering
  • 23.6 timeout: Run a command with a time limit
• 24 Process control
  • 24.1 kill: Send a signal to processes
• 25 Delaying
  • 25.1 sleep: Delay for a specified time
• 26 Numeric operations
  • 26.1 factor: Print prime factors
  • 26.2 numfmt: Reformat numbers
    • 26.2.1 General options
    • 26.2.2 Possible units:
    • 26.2.3 Examples of using numfmt
  • 26.3 seq: Print numeric sequences
• 27 File permissions
  • 27.1 Structure of File Mode Bits
  • 27.2 Symbolic Modes
    • 27.2.1 Setting Permissions
    • 27.2.2 Copying Existing Permissions
    • 27.2.3 Changing Special Mode Bits
    • 27.2.4 Conditional Executability
    • 27.2.5 Making Multiple Changes
    • 27.2.6 The Umask and Protection
  • 27.3 Numeric Modes
  • 27.4 Operator Numeric Modes
  • 27.5 Directories and the Set-User-ID and Set-Group-ID Bits
• 28 File timestamps
• 29 Date input formats
  • 29.1 General date syntax
  • 29.2 Calendar date items
  • 29.3 Time of day items
  • 29.4 Time zone items
  • 29.5 Combined date and time of day items
  • 29.6 Day of week items
  • 29.7 Relative items in date strings
  • 29.8 Pure numbers in date strings
  • 29.9 Seconds since the Epoch
  • 29.10 Specifying time zone rules
  • 29.11 Authors of parse_datetime
• 30 Version sort ordering
  • 30.1 Version sort overview
    • 30.1.1 Using version sort in GNU coreutils
    • 30.1.2 Origin of version sort and differences from natural sort
    • 30.1.3 Correct/Incorrect ordering and Expected/Unexpected results
  • 30.2 Implementation Details
    • 30.2.1 Version-sort ordering rules
    • 30.2.2 Version sort is not the same as numeric sort
    • 30.2.3 Punctuation Characters
    • 30.2.4 Punctuation Characters vs letters
    • 30.2.5 Tilde ‘~’ character
    • 30.2.6 Version sort uses ASCII order, ignores locale, unicode characters
  • 30.3 Differences from the official Debian Algorithm
    • 30.3.1 Minus/Hyphen ‘-’ and Colon ‘:’ characters
    • 30.3.2 Additional hard-coded priorities in GNU coreutils’ version sort
    • 30.3.3 Special handling of file extensions
  • 30.4 Advanced Topics
    • 30.4.1 Comparing two strings using Debian’s algorithm
    • 30.4.2 Reporting bugs or incorrect results
    • 30.4.3 Other version/natural sort implementations
    • 30.4.4 Related Source code
• 31 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
• Appendix A GNU Free Documentation License
• Index

Next: Introduction, Up: (dir)   [Contents][Index]

GNU Coreutils

This manual documents version 8.32 of the GNU core utilities, including the standard programs for text and file manipulation.

Copyright © 1994-2020 Free Software Foundation, Inc.

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, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.

• Introduction

  

Caveats, overview, and authors

• Common options

  

Common options

• Output of entire files

  

cat tac nl od base32 base64 basenc

• Formatting file contents

  

fmt pr fold

• Output of parts of files

  

head tail split csplit

• Summarizing files

  

wc sum cksum b2sum md5sum sha1sum sha2

• Operating on sorted files

  

sort shuf uniq comm ptx tsort

• Operating on fields

  

cut paste join

• Operating on characters

  

tr expand unexpand

• Directory listing

  

ls dir vdir dircolors

• Basic operations

  

cp dd install mv rm shred

• Special file types

  

mkdir rmdir unlink mkfifo mknod ln link readlink

• Changing file attributes

  

chgrp chmod chown touch

• Disk usage

  

df du stat sync truncate

• Printing text

  

echo printf yes

• Conditions

  

false true test expr

• Redirection

  

tee

• File name manipulation

  

dirname basename pathchk mktemp realpath

• Working context

  

pwd stty printenv tty

• User information

  

id logname whoami groups users who

• System context

  

date arch nproc uname hostname hostid uptime

• SELinux context

  

chcon runcon

• Modified command invocation

  

chroot env nice nohup stdbuf timeout

• Process control

  

kill

• Delaying

  

sleep

• Numeric operations

  

factor numfmt seq

• File permissions

  

Access modes

• File timestamps

  

File timestamp issues

• Date input formats

  

Specifying date strings

• Version sort ordering

  

Details on version-sort algorithm

• Opening the software toolbox

  

The software tools philosophy

• GNU Free Documentation License

  

Copying and sharing this manual

• Concept index

  

General index

 — The Detailed Node Listing —

Common Options

• Exit status

  

Indicating program success or failure

• Backup options

  

Backup options

• Block size

  

Block size

• Floating point

  

Floating point number representation

• Signal specifications

  

Specifying signals

• Disambiguating names and IDs

  

chgrp, chown, chroot, id: user and group syntax

• Random sources

  

Sources of random data

• Target directory

  

Target directory

• Trailing slashes

  

Trailing slashes

• Traversing symlinks

  

Traversing symlinks to directories

• Treating / specially

  

Treating / specially

• Standards conformance

  

Standards conformance

• Multi-call invocation

  

Multi-call program invocation

Output of entire files

• cat invocation

  

Concatenate and write files

• tac invocation

  

Concatenate and write files in reverse

• nl invocation

  

Number lines and write files

• od invocation

  

Write files in octal or other formats

• base32 invocation

  

Transform data into printable data

• base64 invocation

  

Transform data into printable data

• basenc invocation

  

Transform data into printable data

Formatting file contents

• fmt invocation

  

Reformat paragraph text

• pr invocation

  

Paginate or columnate files for printing

• fold invocation

  

Wrap input lines to fit in specified width

Output of parts of files

• head invocation

  

Output the first part of files

• tail invocation

  

Output the last part of files

• split invocation

  

Split a file into fixed-size pieces

• csplit invocation

  

Split a file into context-determined pieces

Summarizing files

• wc invocation

  

Print newline, word, and byte counts

• sum invocation

  

Print checksum and block counts

• cksum invocation

  

Print CRC checksum and byte counts

• b2sum invocation

  

Print or check BLAKE2 digests

• md5sum invocation

  

Print or check MD5 digests

• sha1sum invocation

  

Print or check SHA-1 digests

• sha2 utilities

  

Print or check SHA-2 digests

Operating on sorted files

• sort invocation

  

Sort text files

• shuf invocation

  

Shuffle text files

• uniq invocation

  

Uniquify files

• comm invocation

  

Compare two sorted files line by line

• ptx invocation

  

Produce a permuted index of file contents

• tsort invocation

  

Topological sort

ptx: Produce permuted indexes

• General options in ptx

  

Options which affect general program behavior

• Charset selection in ptx

  

Underlying character set considerations

• Input processing in ptx

  

Input fields, contexts, and keyword selection

• Output formatting in ptx

  

Types of output format, and sizing the fields

• Compatibility in ptx

  

The GNU extensions to ptx

Operating on fields

• cut invocation

  

Print selected parts of lines

• paste invocation

  

Merge lines of files

• join invocation

  

Join lines on a common field

Operating on characters

• tr invocation

  

Translate, squeeze, and/or delete characters

• expand invocation

  

Convert tabs to spaces

• unexpand invocation

  

Convert spaces to tabs

tr: Translate, squeeze, and/or delete characters

• Character sets

  

Specifying sets of characters

• Translating

  

Changing one set of characters to another

• Squeezing and deleting

  

Removing characters

Directory listing

• ls invocation

  

List directory contents

• dir invocation

  

Briefly list directory contents

• vdir invocation

  

Verbosely list directory contents

• dircolors invocation

  

Color setup for ls

ls:  List directory contents

• Which files are listed

  

Which files are listed

• What information is listed

  

What information is listed

• Sorting the output

  

Sorting the output

• General output formatting

  

General output formatting

• Formatting the file names

  

Formatting the file names

Basic operations

• cp invocation

  

Copy files and directories

• dd invocation

  

Convert and copy a file

• install invocation

  

Copy files and set attributes

• mv invocation

  

Move (rename) files

• rm invocation

  

Remove files or directories

• shred invocation

  

Remove files more securely

Special file types

• link invocation

  

Make a hard link via the link syscall

• ln invocation

  

Make links between files

• mkdir invocation

  

Make directories

• mkfifo invocation

  

Make FIFOs (named pipes)

• mknod invocation

  

Make block or character special files

• readlink invocation

  

Print value of a symlink or canonical file name

• rmdir invocation

  

Remove empty directories

• unlink invocation

  

Remove files via unlink syscall

Changing file attributes

• chown invocation

  

Change file owner and group

• chgrp invocation

  

Change group ownership

• chmod invocation

  

Change access permissions

• touch invocation

  

Change file timestamps

Disk usage

• df invocation

  

Report file system disk space usage

• du invocation

  

Estimate file space usage

• stat invocation

  

Report file or file system status

• sync invocation

  

Synchronize cached writes to persistent storage

• truncate invocation

  

Shrink or extend the size of a file

Printing text

• echo invocation

  

Print a line of text

• printf invocation

  

Format and print data

• yes invocation

  

Print a string until interrupted

Conditions

• false invocation

  

Do nothing, unsuccessfully

• true invocation

  

Do nothing, successfully

• test invocation

  

Check file types and compare values

• expr invocation

  

Evaluate expressions

test: Check file types and compare values

• File type tests

  

File type tests

• Access permission tests

  

Access permission tests

• File characteristic tests

  

File characteristic tests

• String tests

  

String tests

• Numeric tests

  

Numeric tests

expr: Evaluate expression

• String expressions

  

+ : match substr index length

• Numeric expressions

  

+ - * / %

• Relations for expr

  

| & < <= = == != >= >

• Examples of expr

  

Examples of using expr

Redirection

• tee invocation

  

Redirect output to multiple files or processes

File name manipulation

• basename invocation

  

Strip directory and suffix from a file name

• dirname invocation

  

Strip last file name component

• pathchk invocation

  

Check file name validity and portability

• mktemp invocation

  

Create temporary file or directory

• realpath invocation

  

Print resolved file names

Working context

• pwd invocation

  

Print working directory

• stty invocation

  

Print or change terminal characteristics

• printenv invocation

  

Print all or some environment variables

• tty invocation

  

Print file name of terminal on standard input

stty: Print or change terminal characteristics

• Control

  

Control settings

• Input

  

Input settings

• Output

  

Output settings

• Local

  

Local settings

• Combination

  

Combination settings

• Characters

  

Special characters

• Special

  

Special settings

User information

• id invocation

  

Print user identity

• logname invocation

  

Print current login name

• whoami invocation

  

Print effective user ID

• groups invocation

  

Print group names a user is in

• users invocation

  

Print login names of users currently logged in

• who invocation

  

Print who is currently logged in

System context

• arch invocation

  

Print machine hardware name

• date invocation

  

Print or set system date and time

• nproc invocation

  

Print the number of processors

• uname invocation

  

Print system information

• hostname invocation

  

Print or set system name

• hostid invocation

  

Print numeric host identifier

• uptime invocation

  

Print system uptime and load

date: Print or set system date and time

• Time conversion specifiers

  

%[HIklMNpPrRsSTXzZ]

• Date conversion specifiers

  

%[aAbBcCdDeFgGhjmuUVwWxyY]

• Literal conversion specifiers

  

%[%nt]

• Padding and other flags

  

Pad with zeros, spaces, etc.

• Setting the time

  

Changing the system clock

• Options for date

  

Instead of the current time

• Date input formats

  

Specifying date strings

• Examples of date

  

Examples

SELinux context

• chcon invocation

  

Change SELinux context of file

• runcon invocation

  

Run a command in specified SELinux context

Modified command invocation

• chroot invocation

  

Run a command with a different root directory

• env invocation

  

Run a command in a modified environment

• nice invocation

  

Run a command with modified niceness

• nohup invocation

  

Run a command immune to hangups

• stdbuf invocation

  

Run a command with modified I/O buffering

• timeout invocation

  

Run a command with a time limit

Process control

• kill invocation

  

Sending a signal to processes.

Delaying

• sleep invocation

  

Delay for a specified time

Numeric operations

• factor invocation

  

Print prime factors

• numfmt invocation

  

Reformat numbers

• seq invocation

  

Print numeric sequences

File timestamps

• File timestamps

  

File timestamp issues

File permissions

• Mode Structure

  

Structure of file mode bits

• Symbolic Modes

  

Mnemonic representation of file mode bits

• Numeric Modes

  

File mode bits as octal numbers

• Directory Setuid and Setgid

  

Set-user-ID and set-group-ID on directories

Date input formats

• General date syntax

  

Common rules

• Calendar date items

  

19 Dec 1994

• Time of day items

  

9:20pm

• Time zone items

  

EST, PDT, UTC, …

• Combined date and time of day items

  

1972-09-24T20:02:00,000000-0500

• Day of week items

  

Monday and others

• Relative items in date strings

  

next tuesday, 2 years ago

• Pure numbers in date strings

  

19931219, 1440

• Seconds since the Epoch

  

@1078100502

• Specifying time zone rules

  

TZ="America/New_York", TZ="UTC0"

• Authors of parse_datetime

  

Bellovin, Eggert, Salz, Berets, et al.

Version sorting order

• Version sort overview

  

• Implementation Details

  

• Differences from the official Debian Algorithm

  

• Advanced Topics

  

Opening the software toolbox

• Toolbox introduction

  

Toolbox introduction

• I/O redirection

  

I/O redirection

• The who command

  

The who command

• The cut command

  

The cut command

• The sort command

  

The sort command

• The uniq command

  

The uniq command

• Putting the tools together

  

Putting the tools together

Copying This Manual

• GNU Free Documentation License

  

Copying and sharing this manual

Next: Introduction, Up: (dir)   [Contents][Index]