The ifthenelse program
ifthenelse performs a conditional alternative.
Interface
In an execlineb script:
ifthenelse [ -X ] [ -s ] { progif... } { progthen... } { progelse... } prog...
- ifthenelse reads progif..., progthen... and progelse... in 3 consecutive blocks.
- ifthenelse runs progif... as a child process and waits for it to complete.
- If progif... crashes (i.e. is killed by a signal), ifthenelse prints an error message, then exits 128 plus the number of the signal that killed progif.
- If progif... exits zero, ifthenelse runs progthen... as a child process, else it runs progelse....
- ifthenelse waits for its child to complete and puts the exit status in the ? environment variable. It then execs into prog....
Options
- -X : if progif crashes, do not exit; proceed as if it had returned false.
- -s : magic scoping hack. This option does powerful but ugly things, and is left undocumented on purpose.