How to recursively search directories in a minimal shell (no grep, find, etc.)?

Question

I'm working with an embedded system running QNX that has a stripped-down shell (KSH).

I want to locate all run all executables on the filesystem that match the following:

*/shle/*-*_test

The "shle" directory may appear up to 4 levels deep under root. My current approach is to run the following commands:

for shle in ./shle ./*/shle ./*/*/shle ./*/*/*/shle
do
  for exe in $shle/*-*_test
  do
    echo running: $exe
    $exe
  done
done

Is there a cleaner or faster way of doing this? Are there commands other than grep and find that I should try?

Answer 1

If you don't have find, you can't do much better than what you did: enumerate the levels. If you needed to go down to arbitrary levels, you could do it with a recursive function (but watch out, recursion is tricky when all you have is global variables). Fortunately, with a known maximum depth, it's a lot simpler.

There's a little room for improvement: you'd better put double quotes around all variable substitutions, in case there's a filename somewhere that contains whitespace or special characters. And you aren't testing whether $exe is exists and executable (it could be the pattern …/*-*_test if that pattern doesn't match anything, or perhaps it could be a non-executable file).

for shle in shle */shle */*/shle */*/*/shle; do
  for exe in "$shle"/*-*_test; do
    test -x "$exe" && "$exe"
  done
done

If you don't even have test (if you have ksh, it's built-in, but if it's a stripped-down shell it might be missing), you might get away with a more complicated test to see if the pattern was expanded:

for shle in shle */shle */*/shle */*/*/shle; do
  for exe in "$shle"/*-*_test; do
    case "$exe" in
      */"*-*_test") :;;
      *) "$exe";;
    esac
  done
done

(I'm suprised that you don't have find, I thought QNX came with a full POSIX suite, but I'm unfamiliar with the QNX ecosystem, this could be a stripped-down version of the OS for a small device.)

Answer 2

You could try using the globstar option and specifying **/shle to find the directories that are one or more levels deep.

From the ksh manpage:

          ∗      Matches any string, including the null string.  When used
                 for filename expansion, if the globstar option is on, two
                 adjacent  ∗'s  by itself will match all files and zero or
                 more directories and subdirectories.  If followed by a  /
                 then only directories and subdirectories will match.