Begin a conditional statement. The possible formats, shown here side by side, are:
test-cmdsthen then then
cmds1fi else elif
Usually, the initial if and any elif lines execute one test or [ ] command (although any series of commands is permitted). When if succeeds (that is, the last of its
test-cmds returns 0),
cmds1 are performed; otherwise, each succeeding elif or else line is tried.