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GNU Coreutils 9.0

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GNU Coreutils

This manual documents version 9.0 of the GNU core utilities, including the standard programs for text and file manipulation.

Copyright © 1994–2021 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
• File space 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






File space usage










• df invocation

  

Report file system 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

  

21 Jul 2020




• Time of day items

  

9:20pm




• Time zone items

  

UTC, -0700, +0900, …




• Combined date and time of day items

  

2020-07-21T20:02:00,000000-0400




• Day of week items

  

Monday and others




• Relative items in date strings

  

next tuesday, 2 years ago




• Pure numbers in date strings

  

20200721, 1440




• Seconds since the Epoch

  

@1595289600




• 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]










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