Fix some potential whitespace bugs and shellcheck with strict rules

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
-      - run: shellcheck diff-logs
+      - run: shellcheck -o all -e SC2250,SC2292 diff-logs
       - run: pip install flake8
       - run: flake8 --max-line-length=120 *.py
       - run: echo '2000-01-01T00:00:00' > file.log

diff-logs

@@ -5,17 +5,18 @@
 # See usage instructions below.
 #
 set -eu
+set -o pipefail
 
-lib="$(dirname "$(which "$0")")"
+lib="$(command -v "$0" | dirname -)"
 pyscript="$lib/diff-logs.py"
 difftool="${DIFFTOOL:-diff}"
 
 if [ $# -eq 0 ]; then
-    $pyscript <&0;
+    "$pyscript" <&0;
 elif [ $# -eq 2 ]; then
     case $difftool in diff) args='--color=auto' ;; *) args= ;; esac
-    # shellcheck disable=SC2086
-    $difftool $args <($pyscript < "$1") <($pyscript < "$2");
+    # shellcheck disable=SC2086,SC2248,SC2312
+    $difftool $args <("$pyscript" < "$1") <("$pyscript" < "$2");
 else
     echo "Usage: $0 < FILE1.log           # Print log file diff-frienly" >&2
     echo "       $0 FILE1.log FILE2.log   # Invoke \$DIFFTOOL (e.g. diff)" >&2