added .gitignore manipulation utility

autodeploy/gitignore.sh

@@ -0,0 +1,115 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+
+GITIGNORE=".gitignore"
+
+
+function print_help() {
+cat <<EOF
+Usage: $(basename "$0") <command> [pattern]
+
+Commands:
+  add <pattern>             Add a pattern to $GITIGNORE, if not present
+  remove <pattern>          Remove a pattern from $GITIGNORE, if present
+  has <pattern>             Check if a pattern is present in $GITIGNORE
+  show                      Print $GITIGNORE
+  list                      Print sorted $GITIGNORE, skipping blanks and comments
+  -h, --help                Show this help message
+EOF
+}
+
+
+function add_pattern() {
+    local pat="$1"
+    if pattern_exists "$pat"; then
+        echo "Already present: $pat"
+        return 1
+    fi
+    echo "$pat" >> "$GITIGNORE"
+    echo "Added: $pat"
+}
+
+function remove_pattern() {
+    local pat="$1"
+    if ! pattern_exists "$pat"; then
+        echo "Not present: $pat"
+        return 1
+    fi
+    grep -Fxv "$pat" "$GITIGNORE" > "$GITIGNORE.tmp"
+    mv "$GITIGNORE.tmp" "$GITIGNORE"
+    echo "Removed: $pat"
+}
+
+function has_pattern() {
+    local pat="$1"
+    if pattern_exists "$pat"; then
+        echo "yes"
+        return 0
+    else
+        echo "no"
+        return 1
+    fi
+}
+
+function show_patterns() {
+    cat "$GITIGNORE"
+}
+
+function list_patterns() {
+    grep -v -e '^\s*#' -e '^\s*$' "$GITIGNORE" | sort -u
+}
+
+function pattern_exists() {
+    local pat="$1"
+    grep -Fxq "$pat" "$GITIGNORE"
+}
+
+
+# Check if -h or --help is anywhere in the arguments
+if [[ " $* " == *" -h "* ]] || [[ " $* " == *" --help "* ]]; then
+    print_help
+    exit
+fi
+
+
+cmd="${1:-}"
+pat="${2:-}"
+
+
+# validate number of arguments
+case "$cmd" in
+    add|remove|has)
+        if [[ $# -ne 2 ]]; then
+            echo "Usage: gitignore $cmd <pattern>"
+            exit 1
+        fi
+        ;;
+    show|list)
+        if [[ $# -ne 1 ]]; then
+            echo "Usage: gitignore $cmd"
+            exit 1
+        fi
+        ;;
+    *)
+        print_help
+        exit 1
+        ;;
+esac
+
+
+# ensure .gitignore exists
+touch "$GITIGNORE"
+
+# dispatch command
+case "$cmd" in
+    add)        add_pattern "$pat" ;;
+    remove)     remove_pattern "$pat" ;;
+    has)        has_pattern "$pat" ;;
+    show)       show_patterns ;;
+    list)       list_patterns ;;
+esac
+
+
+