Cleanup redirected output file from failed command

Question

When doing:

CMD > file.out

if CMD fails (non-zero exit code), 'file.out' with be empty or incomplete.

I looking for a way to cleanup in case the CMD fails.

When CMD is run in a CRON job I would prefer for the directed output file to be deleted instead of leaving an empty/incomplete file behind.

My initial idea was:

if ! CMD > file.out; then rm file.out; fi

However it hides the CMD exit status, making it unsuitable. (especially for CRON)

• Can anyone think a better solution ?
• Is there some functionality in bash or sh that would allow this ?
• I was hoping maybe there is some 'tee' like utility that could:
  • It would redirect STDOUT output to a file
  • If the command fails it would remove output file
  • In all case it would return the CMD exit code

Answer 1

Your initial idea is good and could be expanded into

if ! CMD >file.out; then rm file.out; exit 1; fi

If you need to capture the specific exit status from CMD, then do that and exit with it later:

if ! CMD >file.out; then err="$?"; rm file.out; exit "$err"; fi

Note that you can't use exit "$?" since at that point, rm has modified $?.

---

tee will always create its output file, no matter if data is available to put into it, so you would have the same issue as you had from the start.