Reserved words have special meaning to the shell. They do not follow the
usual command argument argument ... format like external commands or
built-in commands. Most reserved words introduce shell flow control
constructs, such as "for" and "while".
| Command | Description |
|---|---|
! |
! pipeline Negate the exit status of pipeline. |
[[ ]] |
[[ expression ]] Same as test expression or [ expression ], except [[ ]] allows additional operators. |
( ) |
( list ) group a list of commands to be executed as a unit within a subshell. |
{ } |
{ list; } group a list of commands to be executed as a unit, without launching a subshell. |
case |
case value in pattern1) cmds1;; pattern2) cmds2;; ... esac execute commands if value matches pattern |
do |
do precedes the command sequence in a for, while, until, or select statement. |
done |
done ends a for, while, until, or select statement. |
elif |
if condition1; then cmds; elif condition2; then cmds2; fi Shortcut for else if. |
else |
if condition; then cmds; else cmds2; fi Execute cmds2 if condition not met. |
esac |
case ... esac Ends a case statement. |
fi |
if ... fi Ends an if statement. |
for |
for var [in list]; do cmds; done Loop through list, each time setting var to value of list item. |
function |
function name { cmds; } Defines name as a shell function. Same as name () { cmds; } |
if |
if condition; then cmds; fi Execute cmds if condition is met. Condition usually involves the test expr, [ expr ], or [[ expr ]] statements. |
in |
for var in list; do cmds; done Part of a "for" statement. |
select |
select NAME in WORDS; do LIST; done User is prompted with a numbered list of the given words. |
then |
if condition; then cmds; fi Part of the "if" statement. |
time |
time [-p] pipeline Report time consumed by pipeline's execution. |
until |
until condition; do cmds; done Loop over commands until condition is true. |
while |
while condition; do cmds; done Loop over commands while condition is true. |