execline
Software
skarnet.org

The ifelse program

ifelse performs conditional execution, with two branches.

Interface

In an execlineb script:

     ifelse [ -X ] [ -n ] { prog1... } { prog2... } prog3...

• ifelse reads prog1... in a block. It forks and executes it, then waits for it to complete.
• If prog1 crashes, ifelse prints an error message and exits 128 plus the number of the signal that killed prog1.
• If prog1 exits with a return code equal to 0, ifelse execs into prog2.
• Else ifelse execs into prog3.

Options

• -n : negate the test.
• -X : do not die if prog1 crashes; treat a crash as a non-zero ("false") exit.

Notes

• ifelse prog1... "" prog2... "" prog3... is roughly equivalent to sh -c 'prog1... && exec prog2... || exec prog3...'.