PATH to Nothing to Distinguish BuiltinsI was reminiscing earlier about how in the old days we would never do
things like #!/usr/bin/env bash because of how insecure it is. Another
thing we would do is set PATH explicitly to make sure nothing could
creep in and take over an external sub-process command without our
saying so by putting it in a safe, well-known, place. Those days are
gone now. There’s little concern for PATH safety now (for whatever
reason) but in the process I realized there is a fun way to check your
shell script’s external dependencies by just setting PATH= to nothing
at the top of the script and watching it fail. Then, you can
incrementally add the directories to that PATH. Another cool way (from
@deyloop) is to export PATH=; before even running your script. You
could even put that in your scripts tool box as nopath and run any
normal command with it instead just to check for dependencies:
#!/bin/bash
cmd=$(which "$1")
shift
export PATH=
exec "$cmd" "$@"
Then try it out:
nopath ls -l # works
nopath foo # won't work if using any subprocesses at all
Related:
man bashTags:
#linux #bash #tips #scripting #coding