Built-in Commands and Keywords (Learning the Korn Shell, 2nd Edition)

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.