[wlug] Re: shellcheck

4 Oct 2023

      On Wed, 4 Oct 2023 11:03:06 +1300, Peter Reutemann wrote:
...
Something useful I came across the other day:
https://www.shellcheck.net/
finds bugs in your shell scripts.
Just for fun, I tried this:

    collect_expand()
      {
        local -n arr="$2"
        arr=()
        coproc expander { find . -maxdepth 1 -name "$1" -print0; }
        # must ensure while-loop runs in this process
        while read -u ${expander[0]} -rd '' line; do
            arr[${#arr[*]}]="$line"
        done
        wait $expander_PID
      } # collect_expand

    #+
    # Mainline
    #-

    test_filenames=('file  1.dat' $'file number\n2.dat' $'file\t3 dat')
      # test multiple spaces in a row and newlines, among any other odd
      # things you can think of!

    tmpdir=$(mktemp -d -p '' collect-work.XXXXXXXXXX)
    echo "tmpdir =" $(printf %q "$tmpdir")

    cd "$tmpdir"
    for f in "${test_filenames[@]}"; do
        echo "create" $(printf %q "$f")
        touch "$f"
    done

    collect_expand '*dat' found_filenames
    for f in "${found_filenames[@]}"; do
        echo "found" $(printf %q "$f")
    done

    cd
    rm -rfv "$tmpdir"

and it came back with

    Line 9:
        while read -u ${expander[0]} -rd '' line; do
                      ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

    Did you mean: (apply this, apply all SC2086)
        while read -u "${expander[0]}" -rd '' line; do

    Line 12:
        wait $expander_PID
             ^-- SC2154 (warning): expander_PID is referenced but not assigned.
             ^-- SC2086 (info): Double quote to prevent globbing and word splitting.

    Did you mean: (apply this, apply all SC2086)
        wait "$expander_PID"

    Line 24:
    echo "tmpdir =" $(printf %q "$tmpdir")
                    ^-- SC2046 (warning): Quote this to prevent word splitting.

    Line 26:
    cd "$tmpdir"
    ^-- SC2164 (warning): Use 'cd ... || exit' or 'cd ... || return' in case cd fails.

    Did you mean: (apply this, apply all SC2164)
    cd "$tmpdir" || exit

    Line 28:
        echo "create" $(printf %q "$f")
                      ^-- SC2046 (warning): Quote this to prevent word splitting.

    Line 33:
    for f in "${found_filenames[@]}"; do
              ^-- SC2154 (warning): found_filenames is referenced but not assigned.

    Line 34:
        echo "found" $(printf %q "$f")
                     ^-- SC2046 (warning): Quote this to prevent word splitting.

    Line 37:
    cd
    ^-- SC2164 (warning): Use 'cd ... || exit' or 'cd ... || return' in case cd fails.

    Did you mean: (apply this, apply all SC2164)
    cd || exit

I would have to count every single one of those messages as spurious.

[wlug] Re: shellcheck

Lawrence D'Oliveiro