allow auto with taz

profile.d/compress.sh

@@ -395,18 +395,32 @@ export -f utaz
 
 # ------------------------------------------------------------------------------
 # Compress directories or files into one or more archive
-# Usage: taz [option] [--parallel=<n>] [--format=<format>] [directory1 ... directoryN]
+# Usage: taz [option] [--parallel=<n|auto>] [--format=<format>] [directory1 ... directoryN]
 # Options:
 # 	-h, --help	Display that help screen
 # 	-d, --delete	Delete source file or directory after success
 # 	-f, --format	Chose archive format in the given list. If several format are
 # 			given, the smalest is kept
-# 	-p, --parallel	Number of threads to use (if allowed by underlying utility)
+# 	-p, --parallel	Number of threads to use, or 'auto' to use detected CPU count
 # 	-v, --verbose	Display progress where possible
 # 	-q, --quiet	Display less messages (only errors and warnings)
 # 	-1, .., -9	Compression level to use [1=fast/biggest, 9=slow/smallest]
 taz()
 {
+    # Resolve runtime CPU count for --parallel=auto.
+    _taz_detect_cpus()
+    {
+        local cpus=1
+        if command -v nproc >/dev/null 2>&1; then
+            cpus=$(nproc 2>/dev/null)
+        elif command -v getconf >/dev/null 2>&1; then
+            cpus=$(getconf _NPROCESSORS_ONLN 2>/dev/null)
+        fi
+
+        [[ $cpus =~ ^[1-9][0-9]*$ ]] || cpus=1
+        printf "%s\n" "$cpus"
+    }
+
     # shellcheck disable=SC2329
     _doxz()
     {
@@ -537,13 +551,13 @@ taz()
         case "$1" in
         -h|--help)
             printf "taz: archive all files of a directory.\n\n"
-            printf "Usage: taz [option] [--parallel=<n>] [--format=<format>] [directory1 ... directoryN]\n\n"
+            printf "Usage: taz [option] [--parallel=<n|auto>] [--format=<format>] [directory1 ... directoryN]\n\n"
             printf "Options:\n"
             printf "\t-h, --help\tDisplay that help screen\n"
             printf "\t-d, --delete\tDelete source file or directory after success\n"
             printf "\t-f, --format\tChose archive format in the given list. If several format are"
             printf "\t\t\tgiven, the smalest is kept\n"
-            printf "\t-p, --parallel\tNumber of threads to use (if allowed by underlying utility)\n"
+            printf "\t-p, --parallel\tNumber of threads, or 'auto' for runtime CPU count\n"
             printf "\t-v, --verbose\tDisplay progress where possible\n"
             printf "\t-q, --quiet\tDisplay less messages (only errors and warnings)\n"
             printf "\t-1, .., -9\tCompression level to use [1=fast/biggest, 9=slow/smallest]\n\n"
@@ -606,11 +620,20 @@ taz()
         [[ ${#FILES[@]} -eq 0 ]] && FILES=(".")
 
     [[ ! $compform ]]   && compform=${TAZ_DEFAULT_FORMAT:-lz}
-    [[ ! $nproc ]]      && nproc=${TAZ_DEFAULT_THREADS:-1}
+    [[ ! $nproc ]]      && nproc=${TAZ_DEFAULT_THREADS:-auto}
     [[ ! $complevel ]]  && complevel=${TAZ_DEFAULT_LEVEL:-6}
     [[ $verbose -gt 1 && $quiet -gt 1 ]] &&
         disp E "The --verbose and --quiet options can't be used together."
 
+    # Backward compatibility: 0 previously meant auto-detect.
+    [[ $nproc == 0 ]] && nproc=auto
+    if [[ $nproc == auto ]]; then
+        nproc=$(_taz_detect_cpus)
+    elif [[ ! $nproc =~ ^[1-9][0-9]*$ ]]; then
+        disp E "Invalid value for --parallel: '$nproc' (expected auto or a positive integer)."
+        return 1
+    fi
+
     for item in "${FILES[@]}"; do
         local donetar=0
         disp I "Processing $item..."