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Bash Hackers Wiki Front page

The Bash-Hackers Wiki This wiki is intended to hold documentation of any kind about GNU Bash. The main motivation was to provide human-readable documentation and information so users aren't forced to read every bit of the Bash manpage - which can be difficult to understand. However, the docs here are not meant as a newbie tutorial.

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This is a selection of builtin commands and command-like keywords, loosely arranged by their common uses. These are provided directly by the shell, rather than invoked as standalone external commands.

Declaration commands
Commands that set and query attributes/types, and manipulate simple datastructures.
Alt Type
declareDisplay or set shell variables or functions along with attributes. typeset builtin
exportDisplay or set shell variables, also giving them the export attribute. typeset -x special builtin
evalEvaluate arguments as shell code. - special builtin
localDeclare variables as having function local scope. - builtin
readonlyMark variables or functions as read-only. typeset -r special builtin
unsetUnset variables and functions. - special builtin
shiftShift positional parameters - special builtin
Commands for reading/parsing input, or producing/formatting output of standard streams.
Alt Type
coprocCo-processes: Run a compound command in the background with async I/O. - keyword
echoCreate output from arguments. - builtin
mapfileRead lines of input into an array. readarray builtin
printf"advanced echo." - builtin
readRead input into variables or arrays, or split strings into fields using delimiters. - builtin
Configuration and Debugging
Commands that modify shell behavior, change special options, assist in debugging.
Alt Type
callerIdentify/print execution frames. - builtin
setSet the positional parameters and/or set options that affect shell behaviour. - special builtin
shoptset/get some bash-specific shell options. - builtin
Control flow and data processing
Commands that operate on data and/or affect control flow.
Alt Type
colon"true" null command. true special builtin
dotSource external files. source special builtin
falseFail at doing nothing. - builtin
continue / breakcontinue with or break out of loops. - special builtin
letArithmetic evaluation simple command. - builtin
returnReturn from a function with a specified exit status. - special builtin
[The classic test simple command. test builtin
Process and Job control
Commands related to jobs, signals, process groups, subshells.
Alt Type
execReplace the current shell process or set redirections. - special builtin
exitExit the shell. - special builtin
trapSet signal handlers or output the current handlers. - special builtin
timesDisplay process times. - special builtin
waitWait for background jobs and asynchronous lists. - builtin
History, programmable completion, directory stack.
Alt Type

previous alphabetical version

calleridentify/print execution frames (Bash builtin)
coprocCo-processes (Bash keyword)
declaredisplay or set shell variables or functions along with attributes (Bash builtin, synonym: typeset)
exec replace the shell, set redirections (Bash builtin)
letarithmetic evaluation - an old fashioned way (Bash builtin)
mapfileMapping lines of input to an array, also named readarray (Bash builtin)
printf"advanced echo" (Bash builtin)
readgetting input from stdin (Bash builtin)
readonlymark variables or functions as read-only (Bash builtin)
setcontrol positional parameters and shell behaviour (Bash builtin)
shoptset/get shell options (Bash builtin)
testthe classic test command (Bash builtin)
unsetunset variables and functions (Bash builtin)
A list of expressions, words, and their meanings is here.

Documentation / Reference

Statistics for Month: April 2012
Rank Views Article
1 6833Small getopts tutorial (March: 11663)
2 4025The printf command (March: 7079)
3 2861Quotes and escaping (March: 5730)
4 2854The classic test command (March: 6145)
5 2222Parameter expansion (March: 4540)
6 1760Handling positional parameters (March: 3591)
7 1249Bash 4 - a rough overview (March: –)
8 1212Editing files via scripts with ed (March: 2727)
9 1205The read builtin command (March: –)
10 1182Lock your script (against parallel execution) (March: –)
  • "Total visits": 35144
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  • Last modified: 2015/08/10 05:09
  • by bill_thomson