Memoize captures and replays outputs of slow (or otherwise expensive) commands.
To capture stdout, stderr, and the return code, just prepend the line with memoize:
memoize bash -c 'sleep 3; echo moo'
To replay them, just re-run the same command:
memoize bash -c 'sleep 3; echo moo'
To clear the cache, add the -d flag before anything else:
memoize -d bash -c 'sleep 3; echo moo'
The cache is keyed on the sha1 of echo "$*" of the line, so there's no logic to try to understand anything. Shell lexing will ignore whitespace between arguments, but that's it.
The results are kept in files named key.rc, key.out, and key.err in
$XDG_CACHE_HOME/memoize, or if XDG_CACHE_HOME is not set
~/.cache/memoize.
It's ok to remove empty files in the cache.