Rewrite to meta-command and add update mode

'newstub' was not so far to being able to update meta-data based on
existing mkit.ini.  However, in order to keep the CLI sane, it seems
better to switch to meta-command scheme.

mkit.ini

 
 [files]
     bin = src/make
-    bin = src/newstub
+    bin = src/stub
     rest = src/include
     rest = src/mkit.mk

src/newstub → src/stub

 
 init_core
 
+mkit_import ini
+
 declare -A MKIT_INIT_LICENSES
 MKIT_INIT_LICENSES[GPLv1]="http://www.gnu.org/licenses/old-licenses/gpl-1.0.md"
 MKIT_INIT_LICENSES[GPLv2]="http://www.gnu.org/licenses/old-licenses/gpl-2.0.md"
 deploy() {
     local file=$1       # which known file?
     local any_name=${NiceName:-$PackageName}
+    local tmp
+    tmp=$(mktemp -t newstub.deploy.XXXXXXX)
     mkdir -p "$(dirname "$file")"
     case $file in
 
             test -n "$VcsBrowser"   && echo "    vcs_browser = $VcsBrowser"
             test -n "$RelSrc"       && echo "    relsrc      = $RelSrc"
             test -n "$RelDst"       && echo "    reldst      = $RelDst"
-            echo ""
-            echo "[dist]"
-            $MkLicense  && echo "    tarball = LICENSE.md"
-            $MkMakefile && echo "    tarball = Makefile"
-            $MkReadme   && echo "    tarball = README.md"
-            echo "    tarball = mkit.ini"
-            $MkPackaging && echo "    tarball = packaging"
-            echo "    tarball = src"
-            echo "    tarball = tests"
-            echo "    tarball = utils"
-            $MkPackaging && echo "    rpmstuff = packaging/template.spec"
-            $MkPackaging && echo "    debstuff = packaging/debian"
-            echo ""
-            echo "[ENV]"
-            echo "    PREFIX = /usr/local"
-            echo ""
-            echo "[roots]"
-            echo "    bin     = [ENV:PREFIX]/bin"
-            echo "    doc     = [ENV:PREFIX]/share/doc/$PackageName"
-            echo ""
-            echo "[tokens]"
-            echo "    __BIN_DIR__ = [roots:bin]"
-            echo ""
-            echo "[modes]"
-            echo "    bin     = 755"
-            echo "    doc     = 644"
-            echo ""
-            echo "[files]"
-            echo "    bin      = src/$PackageName"
-            $MkLicense && echo "    doc      = LICENSE.md"
-            $MkReadme  && echo "    doc      = README.md"
+            if updating; then
+                remake_section dist
+                remake_section ENV
+                remake_section roots
+                remake_section tokens
+                remake_section modes
+                remake_section files
+            else
+                echo ""
+                echo "[dist]"
+                $MkLicense  && echo "    tarball = LICENSE.md"
+                $MkMakefile && echo "    tarball = Makefile"
+                $MkReadme   && echo "    tarball = README.md"
+                echo "    tarball = mkit.ini"
+                $MkPackaging && echo "    tarball = packaging"
+                echo "    tarball = src"
+                echo "    tarball = tests"
+                echo "    tarball = utils"
+                $MkPackaging && echo "    rpmstuff = packaging/template.spec"
+                $MkPackaging && echo "    debstuff = packaging/debian"
+                echo ""
+                echo "[ENV]"
+                echo "    PREFIX = /usr/local"
+                echo ""
+                echo "[roots]"
+                echo "    bin     = [ENV:PREFIX]/bin"
+                echo "    doc     = [ENV:PREFIX]/share/doc/$PackageName"
+                echo ""
+                echo "[tokens]"
+                echo "    __BIN_DIR__ = [roots:bin]"
+                echo ""
+                echo "[modes]"
+                echo "    bin     = 755"
+                echo "    doc     = 644"
+                echo ""
+                echo "[files]"
+                echo "    bin      = src/$PackageName"
+                $MkLicense && echo "    doc      = LICENSE.md"
+                $MkReadme  && echo "    doc      = README.md"
+            fi
             echo ""
             echo "#mkit version=$MKIT_VERSION"
             ;;
             echo "Once you have reviewed everything, just delete this file!"
             ;;
 
-    esac >"$file"
+    esac >"$tmp"
+    cat "$tmp" > "$file"
+    rm "$tmp"
 }
 
 known_licenses() {
 usage() {
     {
         echo "Usage:"
-        echo "   newstub [options] NAME"
+        echo "   newstub [options] new PKGNAME"
+        echo "   newstub [options] update"
         echo "   newstub -L"
         echo ""
         echo "Options:"
         echo "    -P            skip creating packaging templates"
         echo "    -L            list know licenses and exit"
         echo ""
-        echo "NAME should be packaging-friendly name, ie. consist"
+        echo "PKGNAME should be packaging-friendly name, ie. consist"
         echo "only of small letters, numbers, underscore and dash."
         echo "For your 'real' name, use NICENAME, which can be any"
         echo "string."
 
 mkcommit_mkit_conf() {
     git add .                                                  || return
-    git commit -m "WIP [mkit/newstub] Add MKit configuration stub" || return
+    local msg       # commit message (the important art
+    case $Action in
+        new)    msg="Add MKit configuration stub" ;;
+        update) msg="Update MKit configuration"   ;;
+    esac
+    git commit -m "WIP [mkit/newstub] $msg" || return
 }
 
 deploy_packaging() {
     deploy packaging/template.spec
 }
 
+init_from_existing() {
+    #
+    # Initialize variables from old mkit.ini
+    #
+    test -f "$MKIT_INI" \
+     || die "mkit.ini not found; aborting update: $MKIT_INI"
+    user_gave Codename    || Codename=$(ini_raw1v project:codename)
+    user_gave License     || License=$(ini_raw1v project:license)
+    user_gave Maintainer  || Maintainer=$(ini_raw1v project:maintainer)
+    user_gave NiceName    || NiceName=$(ini_raw1v project:name)
+    user_gave PackageName || PackageName=$(ini_raw1v project:pkgname)
+    user_gave RelDst      || RelDst=$(ini_raw1v project:reldst)
+    user_gave RelSrc      || RelSrc=$(ini_raw1v project:relsrc)
+    user_gave Tagline     || Tagline=$(ini_raw1v project:tagline)
+    user_gave VcsBrowser  || VcsBrowser=$(ini_raw1v project:vcs_browser)
+    user_gave Version     || Version=$(ini_raw1v project:version)
+}
+
+ini_raw1v() {
+    #
+    # Read raw scalar from mkit.ini
+    #
+    local path=$1
+    MKIT_INI_EXPAND=0 ini 1value "$path"
+}
+
+user_gave() {
+    #
+    # True if user gave value to variable $1
+    #
+    local var=$1    # name of the variable
+    { test "${UserGave[$var]}" == 1; } 2>/dev/null
+}
+
+updating() {
+    #
+    # Are we updating?
+    #
+    test "$Action" == update
+}
+
+remake_section() {
+    #
+    # Re-compose mkit.ini section $1
+    #
+    local section=$1
+    local key
+    local value
+    ini lskeys "$section" | grep -q . \
+     || return 1
+    echo ""
+    echo "[$section]"
+    ini lskeys "$section" \
+      | while read -r key; do
+            MKIT_INI_EXPAND=0 ini values "$section:$key" \
+              | while read -r value; do
+                    echo "$key = $value"
+                done
+        done \
+      | column -to' ' \
+      | sed 's/^/    /'
+}
+
 main() {
     local NiceName          # human-readable project name
     local PackageName       # machine-safe project (package) name
     local MkMakefile=true   # create Makefile?
     local MkPackaging=true  # create packaging templates?
     local MkLicense=false   # create LICENSE.md file
+    local Action            # 'update' to respect existing, 'new' to force
+                            # rewrite incl. MKIT_NEWSTUB_* placeholders
+    declare -A UserGave
     while true; do case $1 in
-        -n) NiceName=$2;        shift 2 || usage ;;
-        -b) RelSrc=$2;          shift 2 || usage ;;
-        -B) RelDst=$2;          shift 2 || usage ;;
-        -c) Codename=$2;        shift 2 || usage ;;
-        -t) Tagline=$2;         shift 2 || usage ;;
-        -l) License=$2;         shift 2 || usage ;;
-        -m) Maintainer=$2;      shift 2 || usage ;;
-        -v) VcsBrowser=$2;      shift 2 || usage ;;
-        -V) Version=$2;         shift 2 || usage ;;
+        -n) NiceName=$2;   UserGave[NiceName]=1;   shift 2 || usage ;;
+        -b) RelSrc=$2;     UserGave[RelSrc]=1;     shift 2 || usage ;;
+        -B) RelDst=$2;     UserGave[RelDst]=1;     shift 2 || usage ;;
+        -c) Codename=$2;   UserGave[Codename]=1;   shift 2 || usage ;;
+        -t) Tagline=$2;    UserGave[Tagline]=1;    shift 2 || usage ;;
+        -l) License=$2;    UserGave[License]=1;    shift 2 || usage ;;
+        -m) Maintainer=$2; UserGave[Maintainer]=1; shift 2 || usage ;;
+        -v) VcsBrowser=$2; UserGave[VcsBrowser]=1; shift 2 || usage ;;
+        -V) Version=$2;    UserGave[Version]=1;    shift 2 || usage ;;
         -M) MkMakefile=false;   shift ;;
         -R) MkReadme=false;     shift ;;
         -a) AutoClean=true;     shift ;;
         -*) usage ;;
         *)  break ;;
     esac done
-    PackageName="$1"
-    test -n "$PackageName" || usage
+    Action=$1; PackageName=$2
+    case $Action:$PackageName in
+        new:)     usage ;;
+        new:*)    :     ;;
+        update:)  :     ;;
+        update:*) usage ;;
+        *)        usage ;;
+    esac
+    updating && init_from_existing
     if $MkLicense; then
         known_licenses | grep -qxF "$License" \
          || die "unknown license (use -L to get list): $License"