MMANDS; ]... [ else COMMANDS; ] fi
</p>

<p> Execute commands based on conditional.

</p>

<p> The `if COMMANDS' list is executed. If its exit status is zero, then the
    `then COMMANDS' list is executed. Otherwise, each `elif COMMANDS' list is
    executed in turn, and if its exit status is zero, the corresponding
    `then COMMANDS' list is executed and the if command completes. Otherwise,
    the `else COMMANDS' list is executed, if present. The exit status of the
    entire construct is the exit status