execline
Software
skarnet.org

The loopwhilex program

loopwhilex performs a conditional loop.

Interface

     loopwhilex [ -n ] [ -x exitcodes ] 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 0. If prog was killed by a signal, loopwhilex exits that signal's number instead.

Options

• -x exitcodes : exitcodes must be a comma-separated list of valid exit codes. If this option is given, loopwhilex will run prog... as long as its exit code is not listed in breakcodes.
• -n : negate the test: run prog... as long as it exits non-zero (or exits a code that is listed in breakcodes).

Notes

• loopwhilex prog... is equivalent to loopwhilex -n -x 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.