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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