\section if if - Conditionally execute a command \subsection if-synopsis Synopsis <tt>if CONDITION; COMMAND_TRUE [else; COMMAND_FALSE] end;</tt> \subsection if-description Description <tt>if</tt> will execute the command CONDITION. If the commands exit status is zero, the command COMMAND_TRUE will execute. If it is not zero and COMMAND_FALSE is specified, COMMAND_FALSE will be executed. \subsection if-example Example <pre> if test -f foo.txt echo foo.txt exists else echo foo.txt does not exist end </pre> will print <tt>foo.txt exists</tt> if the file foo.txt exists and is a regular file, otherwise it will print <tt>foo.txt does not exist</tt>.