if
expr1
[then] body1
[elseif expr2
[then] body2
...]
[else]
[bodyN
]Execute a conditional expression. If boolean expression
expr1
is true, evaluate
body1
. Otherwise, test optional
additional expressions and execute the matching body. The
optional else keyword is followed by a
command body that is executed if no previous conditional
expressions were true. The keywords then
and else are optional.