​ GNU coreutils basics

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GNU coreutils basics. IMO, nắm được coreutils và triết lý của nolaf là hiểu khoảng 50% command line interface và Unix/Linux :)

GNU Coreutils

This manual documents version 5.93 of the GNU core utilities, including the standard programs for text and file manipulation.

Copyright © 1994, 1995, 1996, 2000, 2001, 2002, 2003, 2004, 2005 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 1.1 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
• 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 uniq comm ptx tsort
• Operating on fields within a line: 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: ln mkdir rmdir mkfifo mknod
• Changing file attributes: chgrp chmod chown touch
• Disk usage: df du stat sync
• Printing text: echo printf yes
• Conditions: false true test expr
• Redirection: tee
• File name manipulation: dirname basename pathchk
• Working context: pwd stty printenv tty
• User information: id logname whoami groups users who
• System context: date uname hostname
• Modified command invocation: chroot env nice nohup su
• 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: The license for this documentation.
• Index: General index.

  --- The Detailed Node Listing ---

  Common Options

• Exit status: Indicating program success or failure.
• Backup options: Backup options
• Block size: Block size
• 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.

  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.
• 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 within a line

• 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
• More 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 the referent of a symbolic link
• 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

  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

  File name manipulation

• basename invocation: Strip directory and suffix from a file name
• dirname invocation: Strip non-directory suffix from a file name
• pathchk invocation: Check file name portability

  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

• date invocation: Print or set system date and time
• uname invocation: Print system information
• hostname invocation: Print or set system name
• hostid invocation: Print numeric host identifier.

  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 zeroes, spaces, etc.
• Setting the time: Changing the system clock.
• Options for date: Instead of the current time.
• Examples of date: Examples.

  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
• su invocation: Run a command with substitute user and group ID

  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 Permissions
• Symbolic Modes: Mnemonic permissions representation
• Numeric Modes: Permissions as octal numbers

  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 get_date: 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
• 
  

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