✨ add a GitHub Action for shellcheck'ing on every PR and push to master branch + shellcheck'ed script

Author: thomasmerz

Diff for: .github/workflows/shellcheck.yml

@@ -0,0 +1,63 @@
+name: Shellcheck Lint
+
+on:
+  push:
+    paths:
+      # Run workflow on every push
+      # only if a file within the specified paths has been changed:
+      - 'lsix'
+
+  pull_request:
+    paths:
+      # Run workflow on every push
+      # only if a file within the specified paths has been changed:
+      - 'lsix'
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Shellcheck Lint
+
+    # This job runs on Linux
+    runs-on: ubuntu-latest
+
+    steps:
+      # Required to access files of this repository
+      - uses: actions/checkout@v4
+
+      # Download Shellcheck and add it to the workflow path
+      - name: Download Shellcheck
+        run: |
+          wget -qO- "https://github.com/koalaman/shellcheck/releases/download/stable/shellcheck-stable.linux.x86_64.tar.xz" | tar -xJv
+          chmod +x shellcheck-stable/shellcheck
+      # Verify that Shellcheck can be executed
+      - name: Check Shellcheck Version
+        run: |
+          shellcheck-stable/shellcheck --version
+
+      # Run Shellcheck on repository
+      # ---
+      # https://github.com/koalaman/shellcheck
+      # ---
+      # Excluded checks:
+      # https://www.shellcheck.net/wiki/SC1091 -- Not following: /etc/rc.status was...
+      # https://www.shellcheck.net/wiki/SC1090 -- Can't follow non-constant source. ..
+      # ---
+      - name: Run Shellcheck
+        run: |
+          set +e
+          find  ./*/ -type f | while read -r sh; do
+            if [ "$(file --brief --mime-type "$sh")" == 'text/x-shellscript' ]; then
+              echo "shellcheck'ing $sh"
+              if ! shellcheck-stable/shellcheck --color=always --severity=warning --exclude=SC1091,SC1090 "$sh"; then
+                touch some_scripts_have_failed_shellcheck
+              fi
+            fi
+          done
+          if [ -f ./some_scripts_have_failed_shellcheck ]; then
+            echo "Shellcheck failed for one or more shellscript(s)"
+            exit 1
+          fi
+

Diff for: lsix

@@ -68,7 +68,7 @@ fi
 if [[ "$COMSPEC" ]]; then
     alias convert="magick convert" # Shun MS Windows' "convert" command.
 fi
-    
+
 cleanup() {
     echo -n $'\e\\'		# Escape sequence to stop SIXEL.
     stty echo			# Reset terminal to show characters.
@@ -193,7 +193,7 @@ main() {
 	readarray -t < <(printf "%s\n" "$@" | sort)
 
 	# Only show first frame of animated GIFs if filename not specified.
-	for x in ${!MAPFILE[@]}; do
+	for x in "${!MAPFILE[@]}"; do
 	    if [[ ${MAPFILE[$x]} =~ (gif|webp)$ ]]; then
 		MAPFILE[$x]="${MAPFILE[$x]}[0]"
 	    fi
@@ -205,7 +205,7 @@ main() {
 	for arg; do
 	    if [ -d "$arg" ]; then
 		echo Recursing on $arg
-		(cd "$arg"; $lsix)
+		(cd "$arg" || exit; $lsix)
 	    else
 		nodirs+=("$arg")
 	    fi
@@ -215,7 +215,7 @@ main() {
 
 
     # Resize on load: Save memory by appending this suffix to every filename.
-    resize="[${tilewidth}x${tileheight}]"
+    #resize="[${tilewidth}x${tileheight}]"  ### DONE: SC2034 (warning): resize appears unused. Verify use (or export if used externally).
 
     imoptions="-tile ${numtiles}x1" # Each montage is 1 row x $numtiles columns
     imoptions+=" -geometry ${tilewidth}x${tileheight}>+${tilexspace}+${tileyspace}" # Size of each tile and spacing
@@ -234,7 +234,7 @@ main() {
 	# While we still have images to process...
 	onerow=()
 	goal=$(($# - numtiles)) # How many tiles left after this row
-	while [ $# -gt 0  -a  $# -gt $goal ]; do
+	while [ $# -gt 0 ] && [ $# -gt $goal ]; do
 	    len=${#onerow[@]}
 	    onerow[len++]="-label"
 	    onerow[len++]=$(processlabel "$1")