The loopwhilex program
loopwhilex performs a conditional loop.
Interface
loopwhilex [ -o okcodes | -x breakcodes ] prog...
- loopwhilex runs prog... as a child process and waits for it to complete.
- As long as prog exits zero, loopwhile runs it again.
- loopwhilex then exits with an approximation of the last prog invocation's exit code.
Options
- -o okcodes : okcodes must be a comma-separated list of exit codes. loopwhilex will keep looping as long as prog exits with one of the codes in okcodes.
- -x breakcodes : like the previous option, but with inverted meaning - the listed exit codes are codes that will break the loop and exit, and the unlisted exit codes will keep the loop running. -x "" will make loopwhilex loop forever.
- If both -o and -x options are given -o has priority and the list given by -x is ignored. If none of these options is given, -o 0 is the default.
Notes
- loopwhilex prog... is equivalent to loopwhilex -n -x 0 prog... and loopwhilex -o 0 prog...
- Be careful: execline maintains no state, in particular it uses no real variables, and environment will be of no use here since every instance of prog... runs as a separate child process. To avoid being stuck in an infinite loop, prog... should modify some external state - for instance, the filesystem.