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...'.