GNU Coreutils

GNU Coreutils

This manual documents version 8.16 of the gnu core utilities, including the standard programs for text and file manipulation.

Copyright © 1994-2012 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 base64
• Formatting file contents: fmt pr fold
• Output of parts of files: head tail split csplit
• Summarizing files: wc sum cksum 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 su timeout
• Process control: kill
• Delaying: sleep
• Numeric operations: factor seq
• File permissions: Access modes
• Date input formats: Specifying date strings
• 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 and chown owner 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

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
• base64 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
• 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: Squeezing repeats and deleting

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
• Details about version sort: More details about version sort
• 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 data on disk with memory
• 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
• su invocation: Run a command with substitute user and group ID
• 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
• seq invocation: Print numeric sequences

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, gmt
• 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

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