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 and or or in the condition. See the second example below.

The exit status of the last foreground command to exit can always be accessed using the $status 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