Book HomeBook TitleSearch this book

B.2. Built-in Commands and Keywords

Here is a summary of all built-in commands and keywords.

Name Command/keyword Chapter Summary
! Keyword 5 Invert the true/false result of the following pipeline.
: Command 7 Do nothing (just do expansions of arguments).
. Command 4 Read file and execute its contents in current shell.
alias Command 3 Set up shorthand for command or command line.
bg Command 8 Put job in background.
builtin Command  

Add or remove built-in commands; print information about them.

break Command 5

Exit from surrounding for, select, while, or until loop.

case Keyword 5 Multiway conditional construct.
cd Command 1 Change working directory.
command Command 5

Locate built-in and external commands; find a built-in command instead of an identically named function.

continue Command 4

Skip to next iteration of for, select, while, or until loop.

disown Command 8

Disassociate a background job from the current shell. The effect is that the job is not sent the HUP signal when the shell exits.

echo Command 4 Expand and print arguments (obsolete).
exec Command 9 Replace shell with given program.
exit Command 5 Exit from shell.
export Command 3 Create environment variables.
eval Command 7 Process arguments as a command line.
false Command 8

Do nothing and exit unsuccessfully. Useful for making infinite loops.

fg Command 8 Put background job in foreground.
for Keyword 5 Looping construct.
function Keyword 4 Define function.
getconf Command  

Get system-specific information. The parameters are defined by POSIX.

getopts Command 6 Process command-line options.
hist Command 2 Work with command history.
if Keyword 5 Conditional construct.
jobs Command 1 List background jobs.
kill Command 8 Send signal to process.
let Command 6 Arithmetic variable assignment.
newgrp Command   Start new shell with new group ID (obsolete).
print Command 1 Expand and print arguments on standard output.
printf Command 7

Expand and print arguments on standard output, using ANSI C printf(3) format specifiers.

pwd Command 1 Print working directory.
read Command 7 Read a line from standard input.
readonly Command 6 Make variables read-only (unassignable).
return Command 5 Return from surrounding function or script.
select Keyword 5 Menu generation construct.
set Command 3 Set options.
shift Command 6 Shift command-line arguments.
sleep Command 8 Suspend execution for the given number of seconds.
test Command 5

Old version of conditional test program. Use [[...]] instead.

time Keyword  

Run command and print execution times. By itself, prints cumulative times for the shell and all children.

trap Command 8 Set up signal-catching routine.
true Command 8

Do nothing and exit successfully. Useful for making infinite loops.

typeset Command 6 Set special characteristics of variables and functions.
ulimit Command 10 Set/show process resource limits.
umask Command 10 Set/show file permission mask.
unalias Command 3 Remove alias definitions.
unset Command 3 Remove definitions of variables or functions.
until Keyword 5 Looping construct.
wait Command 8 Wait for background job(s) to finish.
whence Command 3 Identify source of command.
while Keyword 5 Looping construct.

Assignments for the alias, export, readonly, and typeset commands are processed like variable assignments, in that tilde expansion is done after the = character, and field splitting is not done on any variable substitutions in the value being assigned.



Library Navigation Links

Copyright © 2003 O'Reilly & Associates. All rights reserved.