if - conditionally execute a command¶
Synopsis¶
if CONDITION; COMMANDS_TRUE...; [else if CONDITION2; COMMANDS_TRUE2...;] [else; COMMANDS_FALSE...;] end
Description¶
if
will execute the command CONDITION
. If the condition’s exit status is 0, the commands COMMANDS_TRUE
will execute. If the exit status is not 0 and else
is given, COMMANDS_FALSE
will be executed.
You can use <a href=”#and”>``and``</a> or <a href=”#or”>``or``</a> in the condition. See the second example below.
The exit status of the last foreground command to exit can always be accessed using the <a href=”index.html#variables-status”>$status</a> variable.
Example¶
The following code will print foo.txt exists
if the file foo.txt exists and is a regular file, otherwise it will print bar.txt exists
if the file bar.txt exists and is a regular file, otherwise it will print foo.txt and bar.txt do not exist
.
if test -f foo.txt
echo foo.txt exists
else if test -f bar.txt
echo bar.txt exists
else
echo foo.txt and bar.txt do not exist
end
The following code will print “foo.txt exists and is readable” if foo.txt is a regular file and readable
if test -f foo.txt
and test -r foo.txt
echo "foo.txt exists and is readable"
end