chore(changelog): update changelog for v0.5.1

chore(version): bump to 0.5.1
chore(changelog): update unreleased changelog
2025-06-15 14:52:14 +00:00 · 2025-06-15 16:52:05 +02:00 · 2025-06-15 14:51:30 +00:00 · 2025-06-15 16:51:21 +02:00 · 2025-06-15 16:51:21 +02:00 · 2025-06-15 16:51:21 +02:00
29 changed files with 1376 additions and 324 deletions
--- a/.gitea/default_merge_message/MERGE_TEMPLATE.md
+++ b/.gitea/default_merge_message/MERGE_TEMPLATE.md
@@ -0,0 +1,5 @@
+chore(pr): ${PullRequestTitle} ${PullRequestReference}
+
+${PullRequestDescription}
+
+Merged from ${HeadBranch} into ${BaseBranch}
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -0,0 +1,54 @@
+name: CI
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+  pull_request:
+    types:
+      - opened
+      - synchronize
+      - reopened
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: denoland/setup-deno@v1
+        with:
+          deno-version: v2.x
+
+      - name: Format
+        id: format
+        continue-on-error: true
+        run: deno task fmt
+
+      - name: Lint
+        id: lint
+        continue-on-error: true
+        run: deno task lint
+
+      - name: Test
+        id: test
+        continue-on-error: true
+        run: deno task test
+
+      - name: Compile
+        id: compile
+        continue-on-error: true
+        run: |
+          deno task build:amd64
+          deno task build:arm64
+
+      - name: Fail if any step failed
+        if: |
+          steps.format.outcome != 'success' ||
+          steps.lint.outcome != 'success' ||
+          steps.test.outcome != 'success' ||
+          steps.compile.outcome != 'success'
+        run: |
+          echo "::error::One or more steps failed"
+          exit 1
--- a/.gitea/workflows/release.yml
+++ b/.gitea/workflows/release.yml
@@ -4,219 +4,16 @@ on:
  push:
    branches:
      - main
-      - '**'
+      - "**"

 jobs:
-  detect-version-change:
-    runs-on: ubuntu-latest
-    outputs:
-      version_changed: ${{ steps.set.outputs.version_changed }}
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Check if VERSION file changed
-        if: github.ref == 'refs/heads/main'
-        run: |
-          echo "🔍 Vergleich mit github.event.before:"
-          echo "Before: ${{ github.event.before }}"
-          echo "After:  ${{ github.sha }}"
-
-          echo "📄 Changed files between before and after:"
-          git diff --name-only ${{ github.event.before }} ${{ github.sha }} || echo "(diff failed)"
-
-          if git diff --name-only ${{ github.event.before }} ${{ github.sha }} | grep -q '^VERSION$'; then
-            echo "✅ VERSION file was changed"
-            echo "VERSION_CHANGED=true" >> $GITHUB_ENV
-          else
-            echo "ℹ️ VERSION file not changed"
-            echo "VERSION_CHANGED=false" >> $GITHUB_ENV
-          fi
-
-      - name: Set output (always)
-        id: set
-        run: |
-          echo "version_changed=${VERSION_CHANGED:-false}" >> $GITHUB_OUTPUT
-
-  changelog-only:
-    needs: detect-version-change
-    if: github.ref != 'refs/heads/main' || needs.detect-version-change.outputs.version_changed == 'false'
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Set Git Author
-        run: |
-          git config user.name "$CI_COMMIT_AUTHOR_NAME"
-          git config user.email "$CI_COMMIT_AUTHOR_EMAIL"
-
-      - name: Read CLIFF_VERSION from cliff.toml
-        id: cliff_version
-        run: |
-          echo "version=$(awk -F '=' '/^# CLIFF_VERSION=/ { gsub(/[" ]/, "", $2); print $2 }' cliff.toml)" >> $GITHUB_OUTPUT
-
-      - name: Restore git-cliff cache
-        id: restore-cliff
-        uses: https://git.0xmax42.io/actions/cache@v1
-        with:
-          key: cargo-cliff-${{ steps.cliff_version.outputs.version }}
-          paths: |
-            /root/.cargo/bin
-
-      - name: Install git-cliff
-        if: steps.restore-cliff.outputs.cache-hit != 'true'
-        run: |
-          cargo install git-cliff --version "${{ steps.cliff_version.outputs.version }}" --features gitea
-
-      - name: Generate unreleased changelog (if file exists or on main)
-        run: |
-          if [[ -f CHANGELOG.md || "${GITHUB_REF##refs/heads/}" == "main" ]]; then
-            echo "Generating CHANGELOG.md..."
-            git-cliff -c cliff.toml -o CHANGELOG.md
-          else
-            echo "CHANGELOG.md does not exist and this is not 'main'. Skipping generation."
-          fi
-
-      - name: Commit updated CHANGELOG
-        run: |
-          git add CHANGELOG.md
-          if git diff --cached --quiet; then
-            echo "No changes to commit"
-          else
-            git commit -m "chore(changelog): update unreleased changelog"
-            git push origin "${GITHUB_REF##refs/heads/}"
-          fi
-
  release:
-    needs: detect-version-change
-    if: needs.detect-version-change.outputs.version_changed == 'true' && github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
-
-      - name: Set Git Author
-        run: |
-          git config user.name "$CI_COMMIT_AUTHOR_NAME"
-          git config user.email "$CI_COMMIT_AUTHOR_EMAIL"
-
-      - name: Read VERSION
-        id: version
-        run: echo "value=$(cat VERSION)" >> $GITHUB_OUTPUT
-
-      - name: Read CLIFF_VERSION from cliff.toml
-        id: cliff_version
-        run: |
-          echo "version=$(awk -F '=' '/^# CLIFF_VERSION=/ { gsub(/[" ]/, "", $2); print $2 }' cliff.toml)" >> $GITHUB_OUTPUT
-
-      - name: Restore git-cliff cache
-        id: restore-cliff
-        uses: https://git.0xmax42.io/actions/cache@v1
+      - name: Release
+        uses: https://git.0xmax42.io/actions/auto-changelog-release-action@v0
        with:
-          key: cargo-cliff-${{ steps.cliff_version.outputs.version }}
-          paths: |
-            /root/.cargo/bin
-
-      - name: Install git-cliff
-        if: steps.restore-cliff.outputs.cache-hit != 'true'
-        run: |
-          cargo install git-cliff --version "${{ steps.cliff_version.outputs.version }}" --features gitea
-      
-      - name: Generate changelog for release and tag
-        id: generate-changelog
-        run: |
-          VERSION=${{ steps.version.outputs.value }}
-          git-cliff -c cliff.toml -t "v$VERSION" -o CHANGELOG.md
-
-          BODY=$(mktemp)
-          ESCAPED_VERSION=$(echo "$VERSION" | sed 's/\./\\./g')
-
-          awk -v ver="$ESCAPED_VERSION" '
-            $0 ~ "^## \\[" ver "\\]" {
-              print_flag=1
-              line = $0
-              sub(/^## /, "", line)
-              sub(/\\s*\\(.*\\)/, "", line)  # entfernt z. B. "(...)" oder "(*)"
-              print line
-              next
-            }
-            $0 ~ "^## \\[" && $0 !~ "^## \\[" ver "\\]" {
-              print_flag=0
-            }
-            print_flag
-          ' CHANGELOG.md > "$BODY"
-
-          echo "changelog_body_path=$BODY" >> $GITHUB_OUTPUT
-
-
-      - name: Commit updated CHANGELOG
-        run: |
-          git add CHANGELOG.md
-          if git diff --cached --quiet; then
-            echo "No changes to commit"
-          else
-            git commit -m "chore(changelog): update changelog for v${{ steps.version.outputs.value }}"
-            git push origin main
-          fi
-
-      - name: Create Git tag (if not exists)
-        run: |
-          VERSION=${{ steps.version.outputs.value }}
-          if git rev-parse "v$VERSION" >/dev/null 2>&1; then
-            echo "Tag v$VERSION already exists, skipping tag creation."
-          else
-            git tag -a "v$VERSION" -F "${{ steps.generate-changelog.outputs.changelog_body_path }}" --cleanup=verbatim
-            git push origin "v$VERSION"
-          fi
-
-      - name: Create Gitea release
-        env: 
-          RELEASE_PUBLISH_TOKEN: ${{ secrets.RELEASE_PUBLISH_TOKEN }}
-        run: |
-          VERSION=${{ steps.version.outputs.value }}
-          BODY_FILE="${{ steps.generate-changelog.outputs.changelog_body_path }}"
-
-          OWNER=$(echo "$GITHUB_REPOSITORY" | cut -d/ -f1)
-          REPO=$(echo "$GITHUB_REPOSITORY" | cut -d/ -f2)
-
-          # Token-Auswahl
-          TOKEN="${RELEASE_PUBLISH_TOKEN:-$ACTIONS_RUNTIME_TOKEN}"
-
-          if [[ -z "${RELEASE_PUBLISH_TOKEN:-}" ]]; then
-            echo "::warning title=Limited Release Propagation::"
-            echo "RELEASE_PUBLISH_TOKEN is not set. Using ACTIONS_RUNTIME_TOKEN instead."
-            echo "⚠️  Release events may not trigger other workflows if created with the runtime token."
-            echo
-          fi
-
-          # Prüfe, ob der Release schon existiert
-          if curl -sf "$GITHUB_API_URL/repos/$OWNER/$REPO/releases/tags/v$VERSION" \
-            -H "Authorization: token $TOKEN" > /dev/null; then
-            echo "🔁 Release for tag v$VERSION already exists, skipping."
-            exit 0
-          fi
-
-          echo "🚀 Creating Gitea release for v$VERSION"
-
-          # Release-Beschreibung vorbereiten
-          RELEASE_BODY=$(tail -n +2 "$BODY_FILE" | jq -Rs .)
-
-          curl -X POST "$GITHUB_API_URL/repos/$OWNER/$REPO/releases" \
-            -H "Authorization: token $TOKEN" \
-            -H "Content-Type: application/json" \
-            -d @- <<EOF
-          {
-            "tag_name": "v$VERSION",
-            "target_commitish": "main",
-            "name": "Release v$VERSION",
-            "body": $RELEASE_BODY,
-            "draft": false,
-            "prerelease": false
-          }
-          EOF
-
-          echo "✅ Release for tag $VERSION created successfully."
+          token: ${{ secrets.RELEASE_PUBLISH_TOKEN }}
--- a/.gitea/workflows/upload-assets.yml
+++ b/.gitea/workflows/upload-assets.yml
@@ -42,3 +42,31 @@ jobs:

      - name: Upload SHA256 for ${{ matrix.target }}-${{ matrix.arch }}
        run: .gitea/scripts/upload-asset.sh ./dist/systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.sha256 systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.sha256
+
+      - name: Create zstd compressed archive
+        run: |
+          FILE="./dist/systemd-timer-${{ matrix.target }}-${{ matrix.arch }}"
+          zstd -q -19 -T0 -f "$FILE" -o "$FILE.zst"
+
+      - name: Generate SHA256 for zstd compressed archive
+        run: |
+          FILE="./dist/systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.zst"
+          sha256sum "$FILE" > "$FILE.sha256"
+
+      - name: Upload zstd compressed archive for ${{ matrix.target }}-${{ matrix.arch }}
+        run: .gitea/scripts/upload-asset.sh ./dist/systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.zst systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.zst
+
+      - name: Upload SHA256 for zstd compressed archive
+        run: .gitea/scripts/upload-asset.sh ./dist/systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.zst.sha256 systemd-timer-${{ matrix.target }}-${{ matrix.arch }}.zst.sha256
+
+      - name: Run Releases Sync Action
+        uses: https://git.0xmax42.io/actions/releases-sync@main
+        with:
+          gitea_token: ${{ secrets.RELEASE_PUBLISH_TOKEN }}
+          gitea_url: https://git.0xmax42.io
+          gitea_owner: maxp
+          gitea_repo: systemd-timer
+          tag_name: ${{ github.event.release.tag_name }}
+          github_token: ${{ secrets.SYNC_GITHUB_TOKEN }}
+          github_owner: 0xmax42
+          github_repo: systemd-timer
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -10,6 +10,15 @@
    "peacock.color": "#c75c5c",
    "exportall.config.folderListener": [
        "/src/utils",
-        "/src/types"
-    ]
+        "/src/types",
+        "/src/i18n"
+    ],
+    "deno.enable": true,
+    "[json]": {
+        "editor.defaultFormatter": "denoland.vscode-deno"
+    },
+    "[jsonc]": {
+        "editor.defaultFormatter": "denoland.vscode-deno"
+    },
+    "editor.formatOnSave": true
 }
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,124 @@

 All notable changes to this project will be documented in this file.

+## [0.5.1](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.5.0..v0.5.1) - 2025-06-15
+
+### 🚀 Features
+
+- *(install)* Add support for compressed .zst archives - ([3a1ee0c](https://git.0xmax42.io/maxp/systemd-timer/commit/3a1ee0cfd6ddba8734cde09196803e9ccdd14c5f))
+- *(workflows)* Add zstd compression for build artifacts - ([d9183d2](https://git.0xmax42.io/maxp/systemd-timer/commit/d9183d2f04b03cbdaf9e11bf05f7ce66111123e5))
+
+### 📚 Documentation
+
+- *(readme)* Add input validation and multilingual support - ([ce78cf3](https://git.0xmax42.io/maxp/systemd-timer/commit/ce78cf3a9a14028114e0fb6fcc0973d86c2b2227))
+
+### ⚙️ Miscellaneous Tasks
+
+- *(workflows)* Simplify release workflow with auto-changelog - ([05f3b51](https://git.0xmax42.io/maxp/systemd-timer/commit/05f3b519f56d893a0135736d8b722302c7cdd3f6))
+- *(workflows)* Add locked flag to cargo install for git-cliff - ([6efc151](https://git.0xmax42.io/maxp/systemd-timer/commit/6efc1515ed4f4fb8802405529e4a6e04870ec02a))
+
+## [0.5.0](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.4.1..v0.5.0) - 2025-05-30
+
+### 🚀 Features
+
+- *(cli)* Add validation for command options - ([1c07af4](https://git.0xmax42.io/maxp/systemd-timer/commit/1c07af402b35ba4c2abf89ff5816e791994db536))
+- *(validation)* Add CLI validation helpers for input checks - ([3d95706](https://git.0xmax42.io/maxp/systemd-timer/commit/3d95706d683cac8d279dfb718541a17c42fa5d71))
+- *(build)* Add run permissions to compiled binaries - ([ccb04e4](https://git.0xmax42.io/maxp/systemd-timer/commit/ccb04e49820ff8238d7e7ad853aab5db06d5dc8a))
+- *(ci)* Add compile steps to CI workflow - ([531a02a](https://git.0xmax42.io/maxp/systemd-timer/commit/531a02a6e11a769f2e05888d49ea2b4808d974e3))
+- *(vscode)* Add JSONC formatter configuration - ([c7af1fb](https://git.0xmax42.io/maxp/systemd-timer/commit/c7af1fb6caa46c22b84229745067d05bf60b6f64))
+- *(i18n)* Support loading JSONC translation files - ([4ac5dd4](https://git.0xmax42.io/maxp/systemd-timer/commit/4ac5dd4c88324f99cb6827283ad85bb9718abbeb))
+- *(config)* Add @std/jsonc dependency - ([8f1cb3f](https://git.0xmax42.io/maxp/systemd-timer/commit/8f1cb3fad71ead365d93087963ddb6c7202a9b4f))
+
+### 🐛 Bug Fixes
+
+- *(build)* Update included files to use .jsonc format - ([f3f2c61](https://git.0xmax42.io/maxp/systemd-timer/commit/f3f2c61da0785dce4c6b8c7d8ef0ae9abf098172))
+
+### 🎨 Styling
+
+- *(i18n)* Add comments for clarity and rename files - ([5226269](https://git.0xmax42.io/maxp/systemd-timer/commit/5226269ec2a0b76dfa30ac8d614c3789ff3a837b))
+
+### 🧪 Testing
+
+- *(fs)* Update test descriptions and comments to English - ([c4f4614](https://git.0xmax42.io/maxp/systemd-timer/commit/c4f4614a2daee68f9b33b9676106214c65a1a427))
+- *(fs)* Add rollback tests for writeUnitFiles errors - ([6039d23](https://git.0xmax42.io/maxp/systemd-timer/commit/6039d236eb7de449ce22b1d9ea718389a3e2261d))
+
+### ⚙️ Miscellaneous Tasks
+
+- *(lock)* Update dependencies to latest versions - ([28b23cf](https://git.0xmax42.io/maxp/systemd-timer/commit/28b23cf947ecc57eb7fde541b29c68b41e508e7d))
+
+## [0.4.1](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.4.0..v0.4.1) - 2025-05-28
+
+### 🐛 Bug Fixes
+
+- *(tasks)* Add read permissions to build scripts - ([a22c156](https://git.0xmax42.io/maxp/systemd-timer/commit/a22c156dd3d2cf4a24f0eed699f7dfabfae3837a))
+
+## [0.4.0](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.3.1..v0.4.0) - 2025-05-28
+
+### 🚀 Features
+
+- *(vscode)* Enable Deno support and configure JSON formatting - ([c02da70](https://git.0xmax42.io/maxp/systemd-timer/commit/c02da709028e1fbb175d5091fbd9d3ed2940cdcd))
+- *(ci)* Add CI workflow with format, lint, and test steps - ([9ad407e](https://git.0xmax42.io/maxp/systemd-timer/commit/9ad407e531270445d9657402fa3e826a7dabd880))
+- *(tasks)* Add formatting, linting, and CI tasks - ([07730e5](https://git.0xmax42.io/maxp/systemd-timer/commit/07730e576180be3f6a16b0fda6c6554a86844eee))
+- *(tasks)* Include localization files in build commands - ([440130f](https://git.0xmax42.io/maxp/systemd-timer/commit/440130f782b1fc51053164410ead29397b867892))
+- *(i18n)* Add German and English translations for CLI tool - ([bd5ea80](https://git.0xmax42.io/maxp/systemd-timer/commit/bd5ea80aff5092118920ea897af6c3f5f9fb2a3b))
+- *(i18n)* Add i18n module for localization support - ([c9b4c8b](https://git.0xmax42.io/maxp/systemd-timer/commit/c9b4c8bd71029976fe900b40a2297b52200a216b))
+
+### 🚜 Refactor
+
+- *(cli)* Integrate i18n support across commands - ([2a13ee2](https://git.0xmax42.io/maxp/systemd-timer/commit/2a13ee2539d96d161a9ee398629fa79822d856f2))
+
+### 🎨 Styling
+
+- *(i18n)* Add missing newline at EOF in JSON files - ([54d71ba](https://git.0xmax42.io/maxp/systemd-timer/commit/54d71ba3f00ced25313036d9f10f6fb01feba52a))
+
+### 🧪 Testing
+
+- *(i18n)* Add unit tests for localization functions - ([8efbee1](https://git.0xmax42.io/maxp/systemd-timer/commit/8efbee1ba9b4fc564f5a32fcbc101ff256c5555b))
+
+### ⚙️ Miscellaneous Tasks
+
+- *(vscode)* Update folder listener with i18n directory - ([dfa92d8](https://git.0xmax42.io/maxp/systemd-timer/commit/dfa92d80694b5b104c26e131d1ee7c5cf69ad94c))
+
+## [0.3.1](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.2.3..v0.3.1) - 2025-05-28
+
+### 🚀 Features
+
+- *(cli)* Add options for user, home, and working directory - ([113103f](https://git.0xmax42.io/maxp/systemd-timer/commit/113103f368ead3014165cc708f016a04749f59be))
+
+### 📚 Documentation
+
+- *(readme)* Expand CLI option descriptions for clarity - ([fb2a62d](https://git.0xmax42.io/maxp/systemd-timer/commit/fb2a62d984615caa4035fd5c1e8e64d245499e47))
+
+### 🎨 Styling
+
+- *(workflows)* Fix formatting and whitespace issues - ([c4855ed](https://git.0xmax42.io/maxp/systemd-timer/commit/c4855ed3fbc0ada208690f90932710983daef392))
+
+### ⚙️ Miscellaneous Tasks
+
+- *(workflows)* Consolidate release sync into upload workflow - ([0c1d8be](https://git.0xmax42.io/maxp/systemd-timer/commit/0c1d8be79f0cc331db9029beb46384659f465f6e))
+
+## [0.2.3](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.2.2..v0.2.3) - 2025-05-26
+
+### 🚀 Features
+
+- *(workflows)* Add GitHub release synchronization workflow - ([27c7367](https://git.0xmax42.io/maxp/systemd-timer/commit/27c7367ef1799428cc5a491b25036f77b65758af))
+
+### 📚 Documentation
+
+- *(readme)* Update project time badge interval - ([e3a3e61](https://git.0xmax42.io/maxp/systemd-timer/commit/e3a3e61bce0e62c2397bbc5bde3eff81b915c94a))
+- Add Englisch README - ([cf483de](https://git.0xmax42.io/maxp/systemd-timer/commit/cf483de06b555599052b1d9f97ee98e9233e5a86))
+
+## [0.2.2](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.2.0..v0.2.2) - 2025-05-22
+
+### 🐛 Bug Fixes
+
+- *(install)* Enhance checksum validation with detailed comparison - ([0ca8ed9](https://git.0xmax42.io/maxp/systemd-timer/commit/0ca8ed94ccc4b9fe4ccac331957f01f852999094))
+- *(install)* Ensure compatibility with non-bash shells - ([20d1430](https://git.0xmax42.io/maxp/systemd-timer/commit/20d143035ec6893f680b68dc4a2f6319ca7a5b81))
+
+### 📚 Documentation
+
+- *(readme)* Update installation instructions with script - ([9853f85](https://git.0xmax42.io/maxp/systemd-timer/commit/9853f854c991d87b12cd4fb5e19fce55e7246024))
+
 ## [0.2.0](https://git.0xmax42.io/maxp/systemd-timer/compare/v0.1.0..v0.2.0) - 2025-05-22

 ### 🚀 Features
--- a/README.DE.md
+++ b/README.DE.md
@@ -0,0 +1,110 @@
+# systemd-timer
+
+![Project time](https://waka.0xmax42.io/api/badge/0XMax42/interval:any/project:systemd-timer?label=Project%20time)
+
+Ein einfaches CLI-Tool zum schnellen Erzeugen von systemd `.service` und `.timer` Units – als Ersatz oder moderne Ergänzung zu klassischen `cron`-Jobs.
+
+---
+
+## 🚀 Features
+
+- Erzeugt `.service` und `.timer` Dateien per CLI
+- Unterstützt `--user` Timer (für `~/.config/systemd/user/`)
+- Optionales Logging (`StandardOutput/StandardError`)
+- Unterstützt:
+  - `--calendar`: Zeitplan für den Timer (systemd `OnCalendar`)
+  - `--exec`: Auszuführendes Kommando (`ExecStart`)
+  - `--description`: Beschreibung für die Unit
+  - `--after`: `After=`-Abhängigkeiten in der Service-Unit
+  - `--environment`: Beliebige `Environment=KEY=VALUE` Einträge
+  - `--output`: Zielverzeichnis für die generierten Unit-Dateien
+  - `--run-as`: Setzt `User=` in der Service-Unit (nur systemweite Timer)
+  - `--home`: Setzt `Environment=HOME=…`
+  - `--cwd`: Arbeitsverzeichnis des Prozesses (`WorkingDirectory`)
+  - `--dry-run`: Gibt nur die generierten Inhalte aus, ohne sie zu schreiben
+- Getestet und typisiert mit **Deno** + **Cliffy**
+- Eingaben werden validiert und auf Fehler geprüft;
+  - z.B. muss `--calendar` ein gültiger systemd `OnCalendar` Ausdruck sein
+- Mehrsprachig (Englisch, Deutsch)
+
+---
+
+## 🛠️ Installation
+
+
+Du kannst `systemd-timer` direkt per Shell-Skript installieren:
+
+```bash
+curl -fsSL https://git.0xmax42.io/maxp/systemd-timer/raw/branch/main/scripts/install.sh | sh
+```
+
+Das Skript erkennt automatisch deine Plattform (Linux `amd64` oder `arm64`) und installiert die passende Binary nach `/usr/local/bin`, sofern dies erlaubt ist (ggf. mit `sudo`).
+
+**Hinweis:**
+- Für die Installation ist eine funktionierende Internetverbindung notwendig.
+- Die Integrität der Binary wird mittels SHA256-Prüfsumme verifiziert.
+- Du kannst das Skript vor der Ausführung auch manuell inspizieren:
+
+```bash
+curl -fsSL https://git.0xmax42.io/maxp/systemd-timer/raw/branch/main/scripts/install.sh -o install.sh
+less install.sh
+```
+
+Weitere Optionen und manuelle Installationswege findest du unter [`scripts/install.sh`](scripts/install.sh).
+
+---
+
+## 📦 Beispiel
+
+```bash
+./systemd-timer create \
+  --exec "/usr/local/bin/backup.sh" \
+  --calendar "Mon..Fri 02:00" \
+  --description "Backup Job" \
+  --user \
+  --logfile "/var/log/backup.log"
+```
+
+Erzeugt:
+- `~/.config/systemd/user/backup.service`
+- `~/.config/systemd/user/backup.timer`
+
+Anschließend aktivieren:
+
+```bash
+systemctl --user daemon-reload
+systemctl --user enable --now backup.timer
+```
+
+---
+
+## 🧪 Tests ausführen
+
+```bash
+deno task test
+```
+
+---
+
+## 🧰 Entwickeln
+
+```bash
+deno task start create --exec "/bin/true" --calendar "daily" --dry-run
+```
+
+---
+
+## 🔒 Rechte / Flags
+
+Das Tool benötigt beim Ausführen bzw. Kompilieren:
+
+- `--allow-env` (für `$HOME`)
+- `--allow-write` (zum Schreiben von `.service`/`.timer`)
+
+Beim Entwickeln wird meist `-A` (allow all) verwendet.
+
+---
+
+## 📝 Lizenz
+
+[MIT License](LICENSE)
--- a/README.md
+++ b/README.md
@@ -1,41 +1,61 @@
 # systemd-timer

-![Project time](https://waka.0xmax42.io/api/badge/0XMax42/interval:today/project:systemd-timer?label=Project%20time)
+- ![Project time](https://waka.0xmax42.io/api/badge/0XMax42/interval:any/project:systemd-timer?label=Project%20time)
+- [Deutsche Version dieser Readme](README.DE.md)

-Ein einfaches CLI-Tool zum schnellen Erzeugen von systemd `.service` und `.timer` Units – als Ersatz oder moderne Ergänzung zu klassischen `cron`-Jobs.
+A simple CLI tool for quickly generating systemd `.service` and `.timer` units — as a replacement or modern supplement to classic `cron` jobs.

 ---

 ## 🚀 Features

- Erzeugt `.service` und `.timer` Dateien per CLI
- Unterstützt `--user` Timer (für `~/.config/systemd/user/`)
- Optionales Logging (`StandardOutput/StandardError`)
- Unterstützt:
-  - `--calendar`
-  - `--exec`
-  - `--after`
-  - `--environment`
-  - `--output`
-  - `--dry-run`
- Getestet und typisiert mit Deno + Cliffy
+* Generates `.service` and `.timer` files via CLI
+* Supports `--user` timers (for `~/.config/systemd/user/`)
+* Optional logging (`StandardOutput/StandardError`)
+* Supports:
+  * `--calendar`: Timer schedule (systemd `OnCalendar`)
+  * `--exec`: Command to execute (`ExecStart`)
+  * `--description`: Description for the unit
+  * `--after`: `After=` dependencies in the service unit
+  * `--environment`: Arbitrary `Environment=KEY=VALUE` entries
+  * `--output`: Target directory for the generated unit files
+  * `--run-as`: Sets `User=` in the service unit (only for system-level timers)
+  * `--home`: Sets `Environment=HOME=…`
+  * `--cwd`: Working directory for the process (`WorkingDirectory`)
+  * `--dry-run`: Outputs unit content without writing to disk
+* Tested and fully typed with **Deno** + **Cliffy**
+* Inputs are validated and checked for errors;
+  * e.g., `--calendar` must be a valid systemd `OnCalendar` expression
+* Multilingual (English, German)

 ---

 ## 🛠️ Installation

-```bash
-git clone https://git.0xmax42.io/maxp/systemd-timer.git
-cd systemd-timer
-deno task build
+You can install `systemd-timer` directly via shell script:

-# Binary liegt nun unter ./systemd-timer
-./systemd-timer --help
+```bash
+curl -fsSL https://git.0xmax42.io/maxp/systemd-timer/raw/branch/main/scripts/install.sh | sh
 ```

+The script automatically detects your platform (Linux `amd64` or `arm64`) and installs the appropriate binary to `/usr/local/bin`, if permitted (possibly using `sudo`).
+
+**Note:**
+
+* A working internet connection is required for installation.
+* The integrity of the binary is verified using a SHA256 checksum.
+* You can manually inspect the script before execution:
+
+```bash
+curl -fsSL https://git.0xmax42.io/maxp/systemd-timer/raw/branch/main/scripts/install.sh -o install.sh
+less install.sh
+```
+
+Additional options and manual installation methods are available under [`scripts/install.sh`](scripts/install.sh).
+
 ---

-## 📦 Beispiel
+## 📦 Example

 ```bash
 ./systemd-timer create \
@@ -46,11 +66,12 @@ deno task build
  --logfile "/var/log/backup.log"
 ```

-Erzeugt:
- `~/.config/systemd/user/backup.service`
- `~/.config/systemd/user/backup.timer`
+This creates:

-Anschließend aktivieren:
+* `~/.config/systemd/user/backup.service`
+* `~/.config/systemd/user/backup.timer`
+
+Activate afterwards:

 ```bash
 systemctl --user daemon-reload
@@ -59,7 +80,7 @@ systemctl --user enable --now backup.timer

 ---

-## 🧪 Tests ausführen
+## 🧪 Running Tests

 ```bash
 deno task test
@@ -67,7 +88,7 @@ deno task test

 ---

-## 🧰 Entwickeln
+## 🧰 Development

 ```bash
 deno task start create --exec "/bin/true" --calendar "daily" --dry-run
@@ -75,17 +96,17 @@ deno task start create --exec "/bin/true" --calendar "daily" --dry-run

 ---

-## 🔒 Rechte / Flags
+## 🔒 Permissions / Flags

-Das Tool benötigt beim Ausführen bzw. Kompilieren:
+The tool requires the following permissions when running or compiling:

- `--allow-env` (für `$HOME`)
- `--allow-write` (zum Schreiben von `.service`/`.timer`)
+* `--allow-env` (for `$HOME`)
+* `--allow-write` (to write `.service`/`.timer` files)

-Beim Entwickeln wird meist `-A` (allow all) verwendet.
+During development, usually `-A` (allow all) is used.

 ---

-## 📝 Lizenz
+## 📝 License

 [MIT License](LICENSE)
--- a/2
+++ b/2
@@ -1 +1 @@
-0.2.0
+0.5.1
--- a/deno.jsonc
+++ b/deno.jsonc
@@ -2,8 +2,11 @@
    "tasks": {
        "start": "deno run -A src/mod.ts",
        "test": "deno test -A --coverage **/__tests__/*.test.ts",
-        "build:amd64": "deno compile --target x86_64-unknown-linux-gnu --include=VERSION --allow-env --allow-write --output dist/systemd-timer-linux-amd64 src/mod.ts",
-        "build:arm64": "deno compile --target aarch64-unknown-linux-gnu --include=VERSION --allow-env --allow-write --output dist/systemd-timer-linux-arm64 src/mod.ts"
+        "fmt": "deno fmt --check",
+        "lint": "deno lint",
+        "ci": "deno task fmt && deno task lint && deno task test && build:amd64", // For local CI checks
+        "build:amd64": "deno compile --target x86_64-unknown-linux-gnu --include VERSION --include src/i18n/de.jsonc --include src/i18n/en.jsonc --allow-env --allow-write --allow-read --allow-run --output dist/systemd-timer-linux-amd64 src/mod.ts",
+        "build:arm64": "deno compile --target aarch64-unknown-linux-gnu --include VERSION --include src/i18n/de.jsonc --include src/i18n/en.jsonc --allow-env --allow-write --allow-read --allow-run --output dist/systemd-timer-linux-arm64 src/mod.ts"
    },
    "compilerOptions": {},
    "fmt": {
@@ -20,6 +23,7 @@
    },
    "exclude": [],
    "imports": {
-        "@cliffy/command": "jsr:@cliffy/command@1.0.0-rc.7"
+        "@cliffy/command": "jsr:@cliffy/command@1.0.0-rc.7",
+        "@std/jsonc": "jsr:@std/jsonc@^1.0.2"
    }
 }
--- a/deno.lock
+++ b/deno.lock
@@ -6,6 +6,8 @@
    "jsr:@cliffy/internal@1.0.0-rc.7": "1.0.0-rc.7",
    "jsr:@cliffy/table@1.0.0-rc.7": "1.0.0-rc.7",
    "jsr:@std/fmt@~1.0.2": "1.0.7",
+    "jsr:@std/json@^1.0.2": "1.0.2",
+    "jsr:@std/jsonc@^1.0.2": "1.0.2",
    "jsr:@std/text@~1.0.7": "1.0.13"
  },
  "jsr": {
@@ -37,11 +39,24 @@
    "@std/fmt@1.0.7": {
      "integrity": "2a727c043d8df62cd0b819b3fb709b64dd622e42c3b1bb817ea7e6cc606360fb"
    },
+    "@std/json@1.0.2": {
+      "integrity": "d9e5497801c15fb679f55a2c01c7794ad7a5dfda4dd1bebab5e409cb5e0d34d4"
+    },
+    "@std/jsonc@1.0.2": {
+      "integrity": "909605dae3af22bd75b1cbda8d64a32cf1fd2cf6efa3f9e224aba6d22c0f44c7",
+      "dependencies": [
+        "jsr:@std/json"
+      ]
+    },
    "@std/text@1.0.13": {
      "integrity": "2191c90e6e667b0c3b7dea1cd082137580a93b3c136bad597c0212d5fe006eb1"
    }
  },
  "remote": {
+    "https://deno.land/std@0.192.0/fmt/colors.ts": "d67e3cd9f472535241a8e410d33423980bec45047e343577554d3356e1f0ef4e",
+    "https://deno.land/std@0.192.0/testing/_diff.ts": "1a3c044aedf77647d6cac86b798c6417603361b66b54c53331b312caeb447aea",
+    "https://deno.land/std@0.192.0/testing/_format.ts": "a69126e8a469009adf4cf2a50af889aca364c349797e63174884a52ff75cf4c7",
+    "https://deno.land/std@0.192.0/testing/asserts.ts": "e16d98b4d73ffc4ed498d717307a12500ae4f2cbe668f1a215632d19fcffc22f",
    "https://deno.land/std@0.224.0/assert/_constants.ts": "a271e8ef5a573f1df8e822a6eb9d09df064ad66a4390f21b3e31f820a38e0975",
    "https://deno.land/std@0.224.0/assert/assert.ts": "09d30564c09de846855b7b071e62b5974b001bb72a4b797958fe0660e7849834",
    "https://deno.land/std@0.224.0/assert/assert_almost_equals.ts": "9e416114322012c9a21fa68e187637ce2d7df25bcbdbfd957cd639e65d3cf293",
@@ -168,11 +183,13 @@
    "https://deno.land/std@0.224.0/path/windows/relative.ts": "3e1abc7977ee6cc0db2730d1f9cb38be87b0ce4806759d271a70e4997fc638d7",
    "https://deno.land/std@0.224.0/path/windows/resolve.ts": "8dae1dadfed9d46ff46cc337c9525c0c7d959fb400a6308f34595c45bdca1972",
    "https://deno.land/std@0.224.0/path/windows/to_file_url.ts": "40e560ee4854fe5a3d4d12976cef2f4e8914125c81b11f1108e127934ced502e",
-    "https://deno.land/std@0.224.0/path/windows/to_namespaced_path.ts": "4ffa4fb6fae321448d5fe810b3ca741d84df4d7897e61ee29be961a6aac89a4c"
+    "https://deno.land/std@0.224.0/path/windows/to_namespaced_path.ts": "4ffa4fb6fae321448d5fe810b3ca741d84df4d7897e61ee29be961a6aac89a4c",
+    "https://deno.land/std@0.224.0/testing/mock.ts": "a963181c2860b6ba3eb60e08b62c164d33cf5da7cd445893499b2efda20074db"
  },
  "workspace": {
    "dependencies": [
-      "jsr:@cliffy/command@1.0.0-rc.7"
+      "jsr:@cliffy/command@1.0.0-rc.7",
+      "jsr:@std/jsonc@^1.0.2"
    ]
  }
 }
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -1,5 +1,11 @@
 #!/usr/bin/env bash
-set -euo pipefail
+
+# Fail-safe bash mode
+if [ -n "$BASH_VERSION" ]; then
+  set -euo pipefail
+else
+  set -eu
+fi

 # === Konfiguration ===
 REPO_URL="https://git.0xmax42.io/maxp/systemd-timer/releases/download/latest"
@@ -20,28 +26,71 @@ case "$OS" in
  *) echo "Unsupported OS: $OS" >&2; exit 1 ;;
 esac

-# === Download-URL zusammensetzen ===
-BINARY_FILE="${BINARY_NAME}-${OS}-${ARCH}"
-DOWNLOAD_URL="${REPO_URL}/${BINARY_FILE}"
+# === Datei- und URL-Namen ===
+BASE_NAME="${BINARY_NAME}-${OS}-${ARCH}"
+ZST_NAME="${BASE_NAME}.zst"
+ZST_URL="${REPO_URL}/${ZST_NAME}"
+BIN_URL="${REPO_URL}/${BASE_NAME}"

 echo "📦 Installing ${BINARY_NAME} for ${OS}/${ARCH}..."
-echo "🌐 Downloading from: ${DOWNLOAD_URL}"

-# === Binary herunterladen ===
-TMP_FILE=$(mktemp)
-curl -fsSL "${DOWNLOAD_URL}" -o "${TMP_FILE}"
-chmod +x "${TMP_FILE}"
+USE_ZSTD=false
+if command -v zstd >/dev/null; then
+  echo "✅ 'zstd' found – will use compressed .zst archive"
+  USE_ZSTD=true
+fi

-# === Optional: SHA256-Check ===
-curl -fsSL "${DOWNLOAD_URL}.sha256" -o "${TMP_FILE}.sha256"
-echo "$(cat ${TMP_FILE}.sha256)  ${TMP_FILE}" | sha256sum -c -
+TMP_DIR=$(mktemp -d)
+cleanup() {
+  rm -rf "$TMP_DIR"
+}
+trap cleanup EXIT

-# === Installation ===
+if [ "$USE_ZSTD" = true ]; then
+  echo "🌐 Downloading: ${ZST_URL}"
+  curl -fsSL "$ZST_URL" -o "$TMP_DIR/${ZST_NAME}"
+  echo "🌐 Downloading checksum: ${ZST_URL}.sha256"
+  curl -fsSL "$ZST_URL.sha256" -o "$TMP_DIR/zst.sha256"
+
+  EXPECTED_HASH=$(cut -d ' ' -f1 "$TMP_DIR/zst.sha256")
+  ACTUAL_HASH=$(openssl dgst -sha256 "$TMP_DIR/${ZST_NAME}" | awk '{print $2}')
+
+  if [ "$EXPECTED_HASH" != "$ACTUAL_HASH" ]; then
+    echo "⚠️ Checksum mismatch for .zst archive!"
+    echo "Expected: $EXPECTED_HASH"
+    echo "Actual:   $ACTUAL_HASH"
+    exit 1
+  fi
+
+  echo "📥 Decompressing..."
+  zstd -d -q "$TMP_DIR/${ZST_NAME}" -o "$TMP_DIR/${BASE_NAME}"
+  TMP_FILE="$TMP_DIR/${BASE_NAME}"
+
+else
+  echo "🌐 Downloading uncompressed binary: ${BIN_URL}"
+  curl -fsSL "$BIN_URL" -o "$TMP_DIR/${BASE_NAME}"
+  echo "🌐 Downloading checksum: ${BIN_URL}.sha256"
+  curl -fsSL "$BIN_URL.sha256" -o "$TMP_DIR/binary.sha256"
+
+  EXPECTED_HASH=$(cut -d ' ' -f1 "$TMP_DIR/binary.sha256")
+  ACTUAL_HASH=$(openssl dgst -sha256 "$TMP_DIR/${BASE_NAME}" | awk '{print $2}')
+
+  if [ "$EXPECTED_HASH" != "$ACTUAL_HASH" ]; then
+    echo "⚠️ Checksum mismatch!"
+    echo "Expected: $EXPECTED_HASH"
+    echo "Actual:   $ACTUAL_HASH"
+    exit 1
+  fi
+
+  TMP_FILE="$TMP_DIR/${BASE_NAME}"
+fi
+
+chmod +x "$TMP_FILE"
 echo "🚀 Installing to ${INSTALL_PATH}/${BINARY_NAME}"
 if [ -w "$INSTALL_PATH" ]; then
-  install -m 755 "${TMP_FILE}" "${INSTALL_PATH}/${BINARY_NAME}"
+  install -m 755 "$TMP_FILE" "${INSTALL_PATH}/${BINARY_NAME}"
 else
-  sudo install -m 755 "${TMP_FILE}" "${INSTALL_PATH}/${BINARY_NAME}"
+  sudo install -m 755 "$TMP_FILE" "${INSTALL_PATH}/${BINARY_NAME}"
 fi

 echo "✅ Installation complete: $(command -v ${BINARY_NAME})"
--- a/src/cli/create.ts
+++ b/src/cli/create.ts
@@ -1,39 +1,73 @@
 import { Command } from '@cliffy/command';
 import { generateUnitFiles } from '../templates/unit-generator.ts';
 import { TimerOptions } from '../types/options.ts';
+import { t } from '../i18n/mod.ts';
+import {
+    collectAndValidateAfter,
+    collectAndValidateEnv,
+    validateIdentifier,
+    validateNotEmpty,
+    validatePath,
+    validateSystemdCalendar,
+} from '../utils/mod.ts';

-export const createCommand = new Command()
-    .description('Erzeugt eine systemd .service und .timer Unit')
-    .option(
-        '--name <name:string>',
-        'Name der Unit-Dateien (optional, wird sonst aus dem Exec generiert)',
-    )
-    .option(
-        '--exec <cmd:string>',
-        'Kommando, das durch systemd ausgeführt werden soll',
-        { required: true },
-    )
-    .option('--calendar <time:string>', 'OnCalendar-Ausdruck für den Timer', {
-        required: true,
-    })
-    .option('--description <desc:string>', 'Beschreibung des Timers')
-    .option('--user', 'Erstellt die Unit als User-Timer')
-    .option('--output <dir:string>', 'Zielverzeichnis der Unit-Dateien')
-    .option(
-        '--after <target:string>',
-        'Optionales After= für die Service-Unit',
-        { collect: true },
-    )
-    .option(
-        '--environment <env:string>',
-        'Environment-Variablen im Format KEY=VALUE',
-        { collect: true },
-    )
-    .option(
-        '--logfile <file:string>',
-        'Dateipfad für Log-Ausgabe (stdout/stderr)',
-    )
-    .option('--dry-run', 'Gibt die Unit-Dateien nur aus, ohne sie zu schreiben')
-    .action(async (options: TimerOptions) => {
-        await generateUnitFiles(options);
-    });
+export function createCommand() {
+    return new Command()
+        .description(t('cli_create_description'))
+        .option(
+            '--name <name:string>',
+            t('option_name'),
+            { value: (v) => validateIdentifier(v, '--name') },
+        )
+        .option(
+            '--exec <cmd:string>',
+            t('option_exec'),
+            {
+                required: true,
+                value: (v) => validateNotEmpty(v, '--exec'),
+            },
+        )
+        .option('--calendar <time:string>', t('option_calendar'), {
+            required: true,
+            value: validateSystemdCalendar,
+        })
+        .option('--description <desc:string>', t('option_description'))
+        .option('--user', t('option_user'))
+        .option(
+            '--run-as <user:string>',
+            t('option_run_as'),
+            { value: (v) => validateNotEmpty(v, '--run-as') },
+        )
+        .option(
+            '--home <path:string>',
+            t('option_home'),
+            { value: (v) => validatePath(v, true) },
+        )
+        .option(
+            '--cwd <path:string>',
+            t('option_cwd'),
+            { value: (v) => validatePath(v, true) },
+        )
+        .option('--output <dir:string>', t('option_output'), {
+            value: (v) => validatePath(v, false),
+        })
+        .option(
+            '--after <target:string>',
+            t('option_after'),
+            { collect: true, value: collectAndValidateAfter },
+        )
+        .option(
+            '--environment <env:string>',
+            t('option_environment'),
+            { collect: true, value: collectAndValidateEnv },
+        )
+        .option(
+            '--logfile <file:string>',
+            t('option_logfile'),
+            { value: (v) => validatePath(v, false) },
+        )
+        .option('--dry-run', t('option_dry_run'))
+        .action(async (options: TimerOptions) => {
+            await generateUnitFiles(options);
+        });
+}
--- a/src/cli/main.ts
+++ b/src/cli/main.ts
@@ -1,10 +1,12 @@
 import { Command } from '@cliffy/command';
-import { createCommand } from './create.ts';
 import { getVersion } from '../utils/mod.ts';
+import { t } from '../i18n/mod.ts';
+import { createCommand } from './mod.ts';

-await new Command()
-    .name('systemd-timer')
-    .version(await getVersion())
-    .description('CLI Tool zum Erzeugen von systemd .timer und .service Units')
-    .command('create', createCommand)
-    .parse(Deno.args);
+export async function createCli() {
+    return new Command()
+        .name('systemd-timer')
+        .version(await getVersion())
+        .description(t('cli_description'))
+        .command('create', createCommand());
+}
--- a/src/cli/mod.ts
+++ b/src/cli/mod.ts
@@ -0,0 +1,2 @@
+export { createCommand } from './create.ts';
+export { createCli } from './main.ts';
--- a/src/i18n/tests/i18n.test.ts
+++ b/src/i18n/tests/i18n.test.ts
@@ -0,0 +1,32 @@
+import { assertEquals } from 'https://deno.land/std@0.224.0/assert/mod.ts';
+import { getCurrentLanguage, loadLocale, t } from '../mod.ts';
+
+Deno.test('loadLocale lade Deutsche Übersetzung', async () => {
+    await loadLocale('de');
+    assertEquals(
+        t('error_write_units'),
+        'Fehler beim Schreiben der Units:',
+    );
+    assertEquals(
+        t('unit_written_service', { path: '/tmp/service' }),
+        'Service Unit geschrieben in: /tmp/service',
+    );
+});
+
+Deno.test('t gibt den Schlüssel zurück, wenn dieser nicht gefunden wird', () => {
+    const result = t('non_existent_key');
+    assertEquals(result, 'non_existent_key');
+});
+
+Deno.test('getCurrentLanguage gibt die Fallback Sprache zurück', () => {
+    Deno.env.delete('SYSTEMD_TIMER_LANG');
+    Deno.env.delete('LC_ALL');
+    Deno.env.delete('LC_MESSAGES');
+    Deno.env.delete('LANG');
+    assertEquals(getCurrentLanguage(), 'en');
+});
+
+Deno.test('getCurrentLanguage nutz die `SYSTEMD_TIMER_LANG`, wenn gesetzt', () => {
+    Deno.env.set('SYSTEMD_TIMER_LANG', 'de_DE.UTF-8');
+    assertEquals(getCurrentLanguage(), 'de');
+});
--- a/src/i18n/de.jsonc
+++ b/src/i18n/de.jsonc
@@ -0,0 +1,32 @@
+{
+    // General
+    "cli_description": "CLI-Tool zum Erzeugen von systemd .timer und .service Units",
+    "cli_create_description": "Erzeugt eine systemd .service und .timer Unit",
+    // Options
+    "option_name": "Name der Unit-Dateien (optional, wird sonst aus dem Exec generiert)",
+    "option_exec": "Kommando, das durch systemd ausgeführt werden soll",
+    "option_calendar": "OnCalendar-Ausdruck für den Timer",
+    "option_description": "Beschreibung des Timers",
+    "option_user": "Erstellt die Unit als User-Timer",
+    "option_run_as": "Führe den systemweiten Timer als bestimmter Benutzer aus (setzt User= in der Service-Unit)",
+    "option_home": "HOME-Variable für den Service setzen",
+    "option_cwd": "Arbeitsverzeichnis (WorkingDirectory) für den Service-Prozess",
+    "option_output": "Zielverzeichnis der Unit-Dateien",
+    "option_after": "Optionales After= für die Service-Unit",
+    "option_environment": "Environment-Variablen im Format KEY=VALUE",
+    "option_logfile": "Dateipfad für Log-Ausgabe (stdout/stderr)",
+    "option_dry_run": "Gibt die Unit-Dateien nur aus, ohne sie zu schreiben",
+    // Messages
+    "unit_written_service": "Service Unit geschrieben in: {path}",
+    "unit_written_timer": "Timer Unit geschrieben in: {path}",
+    "hint_header": "\nℹ️  Hinweis:",
+    // Error messages
+    "error_write_units": "Fehler beim Schreiben der Units:",
+    "rollback_failed": "Rollback fehlgeschlagen:",
+    "error_invalid_env": "Ungültiges Environment-Format. Verwende KEY=VALUE.",
+    "error_path_schold_not_be_empty": "Pfad darf nicht leer sein.",
+    "error_path_not_found": "Pfad nicht gefunden: {path}",
+    "error_value_should_not_be_empty": "Wert ({label}) sollte nicht leer sein.",
+    "error_invalid_identifier": "Ungültiger Bezeichner: '{value}' für {identifier}. Erlaubt sind nur alphanumerische Zeichen, Unterstriche und Bindestriche.",
+    "error_invalid_calendar": "Ungültiger OnCalendar-Ausdruck: {value}. Bitte überprüfe die Syntax."
+}
--- a/src/i18n/en.jsonc
+++ b/src/i18n/en.jsonc
@@ -0,0 +1,32 @@
+{
+    // General
+    "cli_description": "CLI tool for generating systemd .timer and .service units",
+    "cli_create_description": "Generates a systemd .service and .timer unit",
+    // Options
+    "option_name": "Name of the unit files (optional, otherwise derived from the exec command)",
+    "option_exec": "Command to be executed by systemd",
+    "option_calendar": "OnCalendar expression for the timer",
+    "option_description": "Description of the timer",
+    "option_user": "Creates the unit as a user timer",
+    "option_run_as": "Runs the system-wide timer as a specific user (sets User= in the service unit)",
+    "option_home": "Sets the HOME variable for the service",
+    "option_cwd": "Working directory (WorkingDirectory) for the service process",
+    "option_output": "Target directory for the unit files",
+    "option_after": "Optional After= directive for the service unit",
+    "option_environment": "Environment variables in the format KEY=VALUE",
+    "option_logfile": "File path for log output (stdout/stderr)",
+    "option_dry_run": "Only outputs the unit files without writing them",
+    // Messages
+    "unit_written_service": "Service unit written to: {path}",
+    "unit_written_timer": "Timer unit written to: {path}",
+    "hint_header": "\nℹ️  Note:",
+    // Error messages
+    "error_write_units": "Error while writing unit files:",
+    "rollback_failed": "Rollback failed:",
+    "error_invalid_env": "Invalid environment format. Use KEY=VALUE.",
+    "error_path_schold_not_be_empty": "Path should not be empty.",
+    "error_path_not_found": "Path not found: {path}",
+    "error_value_should_not_be_empty": "Value ({label}) should not be empty.",
+    "error_invalid_identifier": "Invalid identifier: '{value}' for {identifier}. Only alphanumeric characters, underscores, and hyphens are allowed.",
+    "error_invalid_calendar": "Invalid OnCalendar expression: {value}. Please check the syntax."
+}
--- a/src/i18n/i18n.ts
+++ b/src/i18n/i18n.ts
@@ -0,0 +1,82 @@
+import { parse as parseJsonc } from '@std/jsonc';
+
+/**
+ * Initializes the i18n module by loading
+ * the appropriate locale file based on the system language.
+ */
+export async function initI18n(): Promise<void> {
+    await loadLocale(getCurrentLanguage());
+}
+
+/**
+ * Contains the loaded translations for the current language.
+ * The keys represent i18n identifiers, the values are the localized strings.
+ */
+let translations: Record<string, string> = {};
+
+/**
+ * Loads the translation file for the specified locale.
+ *
+ * Accepts both `.jsonc` (JSON with comments) and plain `.json`.
+ * When both exist, `.jsonc` takes precedence.
+ * Falls back to English ('en') if the specified file does not exist.
+ *
+ * @param locale - The language code (e.g., 'de', 'en') to load
+ * @returns Promise that resolves once the translations have been loaded
+ */
+export async function loadLocale(locale: string): Promise<void> {
+    const extensions = ['jsonc', 'json'];
+    for (const ext of extensions) {
+        try {
+            const localeUrl = new URL(`./${locale}.${ext}`, import.meta.url);
+            const raw = await Deno.readTextFile(localeUrl);
+            // parseJsonc tolerates both pure JSON and JSONC, so we can use it for either.
+            translations = parseJsonc(raw) as Record<string, string>;
+            return;
+        } catch (err) {
+            if (err instanceof Deno.errors.NotFound) {
+                // Continue with next extension.
+                continue;
+            }
+            console.error(`Error parsing locale '${locale}.${ext}':`, err);
+            break;
+        }
+    }
+    if (locale !== 'en') {
+        console.warn(`Locale '${locale}' not found – falling back to 'en'.`);
+        await loadLocale('en');
+    }
+}
+
+/**
+ * Translates a given key using the loaded translation data.
+ * Replaces placeholders in the format `{variable}` with the provided values.
+ *
+ * @param key - The i18n key (e.g., 'timer_created')
+ * @param vars - Optional replacements for placeholders in the string
+ * @returns The translated string, or the key itself if no translation is found
+ */
+export function t(key: string, vars: Record<string, string> = {}): string {
+    let text = translations[key] ?? key;
+    for (const [k, v] of Object.entries(vars)) {
+        text = text.replace(`{${k}}`, v);
+    }
+    return text;
+}
+
+/**
+ * Determines the current language from the system environment.
+ *
+ * Priority: SYSTEMD_TIMER_LANG > LC_ALL > LC_MESSAGES > LANG.
+ *
+ * @returns The language code (e.g., 'de', 'en'), defaults to 'en'
+ */
+export function getCurrentLanguage(): string {
+    return (
+        Deno.env.get('SYSTEMD_TIMER_LANG') ??
+            Deno.env.get('LC_ALL') ??
+            Deno.env.get('LC_MESSAGES') ??
+            Deno.env.get('LANG') ??
+            'en'
+    ).split('.')[0].split('_')[0].toLowerCase();
+}
--- a/src/i18n/mod.ts
+++ b/src/i18n/mod.ts
@@ -0,0 +1 @@
+export { getCurrentLanguage, initI18n, loadLocale, t } from './i18n.ts';
--- a/src/mod.ts
+++ b/src/mod.ts
@@ -1,5 +1,8 @@
-import './cli/main.ts';
+import { createCli } from './cli/mod.ts';
+import { initI18n } from './i18n/mod.ts';

 // ────────────────────────────────────────────────
 // Entry Point for CLI
-// Delegates to src/cli/main.ts, which registers all CLI commands
+
+await initI18n();
+await (await createCli()).parse(Deno.args);
--- a/src/templates/tests/generate.test.ts
+++ b/src/templates/tests/generate.test.ts
@@ -1,4 +1,5 @@
 import {
+    assert,
    assertStringIncludes,
 } from 'https://deno.land/std@0.224.0/assert/mod.ts';
 import { TimerOptions } from '../../types/mod.ts';
@@ -53,3 +54,63 @@ Deno.test('generateUnits berücksichtigt environment und logfile', () => {
    assertStringIncludes(serviceUnit, 'StandardOutput=append:/var/log/job.log');
    assertStringIncludes(serviceUnit, 'StandardError=append:/var/log/job.log');
 });
+
+Deno.test('generateUnits berücksichtigt runAs', () => {
+    const opts: TimerOptions = {
+        exec: '/bin/true',
+        calendar: 'daily',
+        runAs: 'myuser',
+    };
+    const { serviceUnit } = generateUnits('job', opts);
+
+    assertStringIncludes(serviceUnit, 'User=myuser');
+});
+
+Deno.test('generateUnits berücksichtigt home', () => {
+    const opts: TimerOptions = {
+        exec: '/bin/true',
+        calendar: 'daily',
+        home: '/home/myuser',
+    };
+    const { serviceUnit } = generateUnits('job', opts);
+
+    assertStringIncludes(serviceUnit, 'Environment=HOME=/home/myuser');
+});
+
+Deno.test('generateUnits berücksichtigt cwd', () => {
+    const opts: TimerOptions = {
+        exec: '/bin/true',
+        calendar: 'daily',
+        cwd: '/srv/app',
+    };
+    const { serviceUnit } = generateUnits('job', opts);
+
+    assertStringIncludes(serviceUnit, 'WorkingDirectory=/srv/app');
+});
+
+Deno.test('generateUnits verwendet default.target bei User-Timern', () => {
+    const opts: TimerOptions = {
+        exec: '/bin/true',
+        calendar: 'daily',
+        user: true,
+    };
+    const { timerUnit } = generateUnits('job', opts);
+
+    assertStringIncludes(timerUnit, 'WantedBy=default.target');
+});
+
+Deno.test('generateUnits ignoriert runAs bei --user', () => {
+    const opts = {
+        exec: '/bin/true',
+        calendar: 'daily',
+        user: true,
+        runAs: 'should-not-appear',
+    };
+
+    const { serviceUnit } = generateUnits('job', opts);
+
+    assert(
+        !serviceUnit.includes('User=should-not-appear'),
+        'User= sollte bei --user nicht enthalten sein',
+    );
+});
--- a/src/templates/unit-generator.ts
+++ b/src/templates/unit-generator.ts
@@ -1,3 +1,4 @@
+import { t } from '../i18n/mod.ts';
 import { TimerOptions } from '../types/mod.ts';
 import { deriveNameFromExec, writeUnitFiles } from '../utils/mod.ts';

@@ -21,13 +22,13 @@ export async function generateUnitFiles(options: TimerOptions): Promise<void> {

        if (result) {
            const { servicePath, timerPath } = result;
-            console.log(`Service Unit geschrieben in: ${servicePath}`);
-            console.log(`Timer Unit geschrieben in: ${timerPath}`);
+            console.log(t('unit_written_service', { path: servicePath }));
+            console.log(t('unit_written_timer', { path: timerPath }));
        } else {
            return;
        }

-        console.log(`\nℹ️  Hinweis:`);
+        console.log(t('hint_header'));

        if (options.user) {
            console.log(`  systemctl --user daemon-reload`);
@@ -51,14 +52,18 @@ export function generateUnits(name: string, options: TimerOptions): {
        `[Service]`,
        `Type=oneshot`,
        `ExecStart=${options.exec}`,
+        ...(options.cwd ? [`WorkingDirectory=${options.cwd}`] : []),
        ...(options.environment?.map((e) => `Environment=${e}`) ?? []),
+        ...(options.home ? [`Environment=HOME=${options.home}`] : []),
+        ...(options.logfile
+            ? [
+                `StandardOutput=append:${options.logfile}`,
+                `StandardError=append:${options.logfile}`,
+            ]
+            : []),
+        ...(options.runAs && !options.user ? [`User=${options.runAs}`] : []),
    ];

-    if (options.logfile) {
-        unitParts.push(`StandardOutput=append:${options.logfile}`);
-        unitParts.push(`StandardError=append:${options.logfile}`);
-    }
-
    const serviceUnit = unitParts.join('\n');

    const timerParts = [
@@ -70,7 +75,7 @@ export function generateUnits(name: string, options: TimerOptions): {
        `Persistent=true`,
        ``,
        `[Install]`,
-        `WantedBy=timers.target`,
+        `WantedBy=${options.user ? 'default.target' : 'timers.target'}`,
    ];

    const timerUnit = timerParts.join('\n');
--- a/src/types/options.ts
+++ b/src/types/options.ts
@@ -4,6 +4,9 @@ export interface TimerOptions {
    calendar: string;
    description?: string;
    user?: boolean;
+    runAs?: string;
+    home?: string;
+    cwd?: string;
    output?: string;
    after?: string[];
    environment?: string[];
--- a/src/utils/tests/cliValidationHelper.test.ts
+++ b/src/utils/tests/cliValidationHelper.test.ts
@@ -0,0 +1,145 @@
+import { resolve } from 'https://deno.land/std@0.224.0/path/mod.ts';
+import { ValidationError } from '@cliffy/command';
+import {
+    collectAndValidateAfter,
+    collectAndValidateEnv,
+    validateIdentifier,
+    validateNotEmpty,
+    validatePath,
+    validateSystemdCalendar,
+} from '../mod.ts';
+import { t } from '../../i18n/mod.ts';
+import {
+    assertEquals,
+    assertThrows,
+} from 'https://deno.land/std@0.224.0/assert/mod.ts';
+
+Deno.test(
+    'collectAndValidateEnv: throws ValidationError for invalid env format',
+    () => {
+        const invalidEnv = 'INVALID_ENV';
+        assertThrows(
+            () => collectAndValidateEnv(invalidEnv),
+            ValidationError,
+            t('error_invalid_env', { value: invalidEnv }),
+        );
+    },
+);
+
+Deno.test(
+    'collectAndValidateEnv: returns collected array for valid env format',
+    () => {
+        const validEnv = 'KEY=value';
+        const previous = ['EXISTING=env'];
+        const result = collectAndValidateEnv(validEnv, previous);
+        assertEquals(result, ['EXISTING=env', 'KEY=value']);
+    },
+);
+
+Deno.test('collectAndValidateEnv: aggregates multiple calls', () => {
+    const first = collectAndValidateEnv('FOO=bar');
+    const second = collectAndValidateEnv('BAZ=qux', first);
+    assertEquals(second, ['FOO=bar', 'BAZ=qux']);
+});
+
+Deno.test(
+    'validatePath: returns absolute path for valid path without existence check',
+    () => {
+        const tmpDir = Deno.makeTempDirSync();
+        const relativePath = `${tmpDir}/testfile.txt`;
+        const result = validatePath(relativePath, false);
+        assertEquals(result, resolve(relativePath));
+    },
+);
+
+Deno.test(
+    'validatePath: throws ValidationError for non‑existent path with existence check',
+    () => {
+        const tmpDir = Deno.makeTempDirSync();
+        const nonExistentPath = `${tmpDir}/nonexistent.txt`;
+        assertThrows(
+            () => validatePath(nonExistentPath, true),
+            ValidationError,
+            t('error_path_not_found', { path: resolve(nonExistentPath) }),
+        );
+    },
+);
+
+Deno.test(
+    'validatePath: returns absolute path for existing path with existence check',
+    () => {
+        const tmpDir = Deno.makeTempDirSync();
+        const existingPath = `${tmpDir}/existing.txt`;
+        Deno.writeTextFileSync(existingPath, 'test content');
+        const result = validatePath(existingPath, true);
+        assertEquals(result, resolve(existingPath));
+    },
+);
+
+Deno.test('validatePath: throws ValidationError for empty path', () => {
+    const invalidPath = '';
+    assertThrows(
+        () => validatePath(invalidPath, true),
+        ValidationError,
+        t('error_path_schold_not_be_empty'),
+    );
+});
+
+Deno.test('validateNotEmpty: returns value for non‑empty string', () => {
+    const input = 'some-value';
+    const result = validateNotEmpty(input, '--exec');
+    assertEquals(result, input);
+});
+
+Deno.test('validateNotEmpty: throws ValidationError for empty string', () => {
+    const input = '';
+    assertThrows(
+        () => validateNotEmpty(input, '--exec'),
+        ValidationError,
+        t('error_value_should_not_be_empty', { label: '--exec' }),
+    );
+});
+
+Deno.test('collectAndValidateAfter: returns aggregated array', () => {
+    const first = collectAndValidateAfter('network.target');
+    const second = collectAndValidateAfter('postgres.service', first);
+    assertEquals(second, ['network.target', 'postgres.service']);
+});
+
+Deno.test('collectAndValidateAfter: throws ValidationError for empty value', () => {
+    assertThrows(
+        () => collectAndValidateAfter(''),
+        ValidationError,
+        t('error_value_should_not_be_empty', { label: '--after' }),
+    );
+});
+
+Deno.test('validateIdentifier: returns value for valid identifier', () => {
+    const id = 'backup_job-1';
+    const result = validateIdentifier(id, '--name');
+    assertEquals(result, id);
+});
+
+Deno.test('validateIdentifier: throws ValidationError for invalid identifier', () => {
+    const id = 'invalid$';
+    assertThrows(
+        () => validateIdentifier(id, '--name'),
+        ValidationError,
+        t('error_invalid_identifier', { label: '--name', value: id }),
+    );
+});
+
+Deno.test('validateSystemdCalendar: accepts valid expression', async () => {
+    const valid = 'Mon..Fri 12:00';
+    const result = await validateSystemdCalendar(valid);
+    assertEquals(result, valid);
+});
+
+Deno.test('validateSystemdCalendar: rejects invalid expression', async () => {
+    const invalid = 'Mo..Fr 12:00';
+    await assertThrows(
+        () => validateSystemdCalendar(invalid),
+        ValidationError,
+        t('error_invalid_calendar', { value: invalid }),
+    );
+});
--- a/src/utils/tests/fs.test.ts
+++ b/src/utils/tests/fs.test.ts
@@ -3,11 +3,13 @@ import {
    assertExists,
    assertStringIncludes,
 } from 'https://deno.land/std@0.224.0/assert/mod.ts';
+import { stub } from 'https://deno.land/std@0.224.0/testing/mock.ts';
+import { exists } from 'https://deno.land/std@0.224.0/fs/mod.ts';
 import { join } from 'https://deno.land/std@0.224.0/path/mod.ts';
 import { resolveUnitTargetPath, writeUnitFiles } from '../mod.ts';
 import { TimerOptions } from '../../types/options.ts';

-Deno.test('writeUnitFiles schreibt .service und .timer korrekt', async () => {
+Deno.test('writeUnitFiles: writes .service and .timer files correctly', async () => {
    const tmp = await Deno.makeTempDir({ prefix: 'test-units-' });

    const options = {
@@ -26,15 +28,15 @@ Deno.test('writeUnitFiles schreibt .service und .timer korrekt', async () => {
        options as TimerOptions,
    ) as { servicePath: string; timerPath: string };

-    // Überprüfe Pfade
+    // Check file paths
    assertEquals(servicePath, join(tmp, 'test-backup.service'));
    assertEquals(timerPath, join(tmp, 'test-backup.timer'));

-    // Existieren Dateien?
+    // Check if files exist
    assertExists(await Deno.stat(servicePath));
    assertExists(await Deno.stat(timerPath));

-    // Enthält die Datei den erwarteten Inhalt?
+    // Check if file contents match expectations
    const readService = await Deno.readTextFile(servicePath);
    const readTimer = await Deno.readTextFile(timerPath);

@@ -42,18 +44,237 @@ Deno.test('writeUnitFiles schreibt .service und .timer korrekt', async () => {
    assertStringIncludes(readTimer, 'OnCalendar=daily');
 });

-Deno.test('resolveUnitTargetPath mit --output', () => {
+Deno.test('resolveUnitTargetPath: with --output', () => {
    const result = resolveUnitTargetPath({ output: '/tmp/units', user: false });
    assertEquals(result, '/tmp/units');
 });

-Deno.test('resolveUnitTargetPath mit --user ohne output', () => {
+Deno.test('resolveUnitTargetPath: with --user and no output', () => {
    Deno.env.set('HOME', '/home/maxp');
    const result = resolveUnitTargetPath({ output: undefined, user: true });
    assertEquals(result, '/home/maxp/.config/systemd/user');
 });

-Deno.test('resolveUnitTargetPath ohne output und ohne user', () => {
+Deno.test('resolveUnitTargetPath: with no output and no user', () => {
    const result = resolveUnitTargetPath({ output: undefined, user: false });
    assertEquals(result, '/etc/systemd/system');
 });
+
+Deno.test('writeUnitFiles: error writing .timer file triggers rollback', async () => {
+    const tmp = await Deno.makeTempDir();
+
+    const options: TimerOptions = {
+        output: tmp,
+        user: false,
+        exec: '/bin/true',
+        calendar: 'never',
+    };
+
+    const name = 'fail-timer';
+    const serviceContent = '[Service]\nExecStart=/bin/true';
+    const timerContent = '[Timer]\nOnCalendar=never';
+
+    const servicePath = join(tmp, `${name}.service`);
+    const timerPath = join(tmp, `${name}.timer`);
+
+    // Simulate: writing the .timer file fails
+    const originalWrite = Deno.writeTextFile;
+    const writeStub = stub(
+        Deno,
+        'writeTextFile',
+        async (path: string | URL, data: string | ReadableStream<string>) => {
+            if (typeof path === 'string' && path.endsWith('.timer')) {
+                throw new Error('Simulated write error');
+            } else {
+                return await originalWrite(path, data);
+            }
+        },
+    );
+
+    const result = await writeUnitFiles(
+        name,
+        serviceContent,
+        timerContent,
+        options,
+    );
+
+    // Expect: function returns undefined
+    assertEquals(result, undefined);
+
+    // Expect: both files have been deleted (rollback)
+    assertEquals(await exists(servicePath), false);
+    assertEquals(await exists(timerPath), false);
+
+    writeStub.restore();
+});
+
+Deno.test('writeUnitFiles: error writing .service file prevents further actions', async () => {
+    const tmp = await Deno.makeTempDir();
+
+    const options: TimerOptions = {
+        output: tmp,
+        user: false,
+        exec: '/bin/true',
+        calendar: 'weekly',
+    };
+
+    const name = 'fail-service';
+    const serviceContent = '[Service]\nExecStart=/bin/true';
+    const timerContent = '[Timer]\nOnCalendar=weekly';
+
+    const servicePath = join(tmp, `${name}.service`);
+    const timerPath = join(tmp, `${name}.timer`);
+
+    // Simulate: error writing the .service file
+    const writeStub = stub(
+        Deno,
+        'writeTextFile',
+        (path: string | URL, _data: string | ReadableStream<string>) => {
+            if (typeof path === 'string' && path.endsWith('.service')) {
+                throw new Error('Simulated service write error');
+            }
+            return Promise.resolve();
+        },
+    );
+
+    const result = await writeUnitFiles(
+        name,
+        serviceContent,
+        timerContent,
+        options,
+    );
+
+    // Expect: function returns undefined
+    assertEquals(result, undefined);
+
+    // Expect: no files were created
+    assertEquals(await exists(servicePath), false);
+    assertEquals(await exists(timerPath), false);
+
+    writeStub.restore();
+});
+
+Deno.test('writeUnitFiles: both files written, then error → full rollback', async () => {
+    const tmp = await Deno.makeTempDir();
+
+    const options: TimerOptions = {
+        output: tmp,
+        user: false,
+        exec: '/bin/true',
+        calendar: 'never',
+    };
+
+    const name = 'fail-after-write';
+    const serviceContent = '[Service]\nExecStart=/bin/true';
+    const timerContent = '[Timer]\nOnCalendar=never';
+
+    const servicePath = join(tmp, `${name}.service`);
+    const timerPath = join(tmp, `${name}.timer`);
+
+    let writeCount = 0;
+    const originalWriteTextFile = Deno.writeTextFile;
+
+    const writeStub = stub(
+        Deno,
+        'writeTextFile',
+        async (path: string | URL, data: string | ReadableStream<string>) => {
+            if (typeof path !== 'string') {
+                throw new Error('Unexpected path type');
+            }
+
+            // Simulate both writes, then throw an error after the second
+            writeCount++;
+
+            await originalWriteTextFile(path, data);
+
+            if (writeCount === 2) {
+                throw new Error('Simulated error after full write');
+            }
+        },
+    );
+
+    const result = await writeUnitFiles(
+        name,
+        serviceContent,
+        timerContent,
+        options,
+    );
+
+    // Expect: function returns undefined
+    assertEquals(result, undefined);
+
+    // Expect: both files were removed
+    assertEquals(await exists(servicePath), false);
+    assertEquals(await exists(timerPath), false);
+
+    writeStub.restore();
+});
+
+Deno.test('writeUnitFiles: rollback fails if files cannot be deleted', async () => {
+    const tmp = await Deno.makeTempDir();
+
+    const options: TimerOptions = {
+        output: tmp,
+        user: false,
+        exec: '/bin/true',
+        calendar: 'never',
+    };
+
+    const name = 'rollback-error';
+    const serviceContent = '[Service]\nExecStart=/bin/true';
+    const timerContent = '[Timer]\nOnCalendar=never';
+
+    const servicePath = join(tmp, `${name}.service`);
+    const timerPath = join(tmp, `${name}.timer`);
+
+    const originalWriteTextFile = Deno.writeTextFile;
+    const _originalRemove = Deno.remove;
+
+    let writeCount = 0;
+
+    const writeStub = stub(
+        Deno,
+        'writeTextFile',
+        async (path: string | URL, data: string | ReadableStream<string>) => {
+            writeCount++;
+            await originalWriteTextFile(path, data);
+            if (writeCount === 2) {
+                throw new Error('Error after full write');
+            }
+        },
+    );
+
+    const removeStub = stub(
+        Deno,
+        'remove',
+        // deno-lint-ignore require-await
+        async (_path: string | URL, _opts?: Deno.RemoveOptions) => {
+            throw new Error('Deletion forbidden!');
+        },
+    );
+
+    const logs: string[] = [];
+    const consoleStub = stub(console, 'error', (...args) => {
+        logs.push(args.map((a) => String(a)).join(' '));
+    });
+
+    const result = await writeUnitFiles(
+        name,
+        serviceContent,
+        timerContent,
+        options,
+    );
+    assertEquals(result, undefined);
+
+    // Files still exist because deletion failed
+    assertEquals(await exists(servicePath), true);
+    assertEquals(await exists(timerPath), true);
+
+    // Error output contains "rollback_failed"
+    const combinedLogs = logs.join('\n');
+    assertStringIncludes(combinedLogs, 'rollback_failed');
+
+    writeStub.restore();
+    removeStub.restore();
+    consoleStub.restore();
+});
--- a/src/utils/cliValidationHelper.ts
+++ b/src/utils/cliValidationHelper.ts
@@ -0,0 +1,176 @@
+import { ValidationError } from '@cliffy/command';
+import { t } from '../i18n/mod.ts';
+import { existsSync } from 'https://deno.land/std@0.224.0/fs/mod.ts';
+import { resolve } from 'https://deno.land/std@0.224.0/path/mod.ts';
+
+/**
+ * Collects repeated occurrences of the `--environment` CLI option and validates
+ * that every entry adheres to `KEY=value` syntax.
+ *
+ * Cliffy calls this handler for *each* `--environment` argument. The previously
+ * accumulated values are passed in via the `previous` parameter, allowing us to
+ * build up the final array manually.
+ *
+ * @example
+ * ```ts
+ * // CLI invocation:
+ * //   mycli --environment FOO=bar --environment BAZ=qux
+ * const env = collectAndValidateEnv("FOO=bar");
+ * const env2 = collectAndValidateEnv("BAZ=qux", env);
+ * console.log(env2); // => ["FOO=bar", "BAZ=qux"]
+ * ```
+ *
+ * @param value - Current `KEY=value` string supplied by the user.
+ * @param previous - Array of values collected so far (defaults to an empty
+ *   array on the first call).
+ * @returns The updated array containing all validated `KEY=value` pairs.
+ *
+ * @throws {ValidationError} If the input does not match the required syntax
+ *   The resulting error is caught by Cliffy, which
+ *   will print a help message and terminate with a non-zero exit code.
+ */
+export function collectAndValidateEnv(
+    value: string,
+    previous: string[] = [],
+): string[] {
+    if (!/^\w+=.+/.test(value)) {
+        throw new ValidationError(t('error_invalid_env', { value }));
+    }
+    previous.push(value);
+    return previous;
+}
+
+/**
+ * Normalises a given path to its absolute representation and optionally checks
+ * whether it exists on the filesystem.
+ *
+ * @remarks
+ * Because `--home`, `--cwd`, `--output`, and similar options may refer to files
+ * or directories that *must* already exist, this helper performs the common
+ * validation in a single place.
+ *
+ * @param value - Path provided by the user (absolute or relative).
+ * @param mustExist - When `true`, the function asserts that the resolved path
+ *   exists; otherwise, existence is not verified.
+ * @returns The absolute path derived via {@linkcode resolve}.
+ *
+ * @throws {ValidationError}
+ *  - If `value` is empty or not a string.
+ *  - If `mustExist` is `true` **and** the resolved path cannot be found.
+ */
+export function validatePath(value: string, mustExist: boolean): string {
+    if (!value || typeof value !== 'string') {
+        throw new ValidationError(t('error_path_schold_not_be_empty'));
+    }
+    const abs = resolve(value);
+    if (mustExist && !existsSync(abs)) {
+        throw new ValidationError(t('error_path_not_found', { path: abs }));
+    }
+    return abs;
+}
+
+/**
+ * Ensures that a mandatory CLI argument is not empty.
+ *
+ * @param value - Raw string supplied by the user.
+ * @param label - Human-readable label identifying the option (used in error
+ *   messages). Example: `"--exec"`.
+ * @returns The original `value` if the validation passes.
+ *
+ * @throws {ValidationError} When `value` is `""`, `null`, `undefined`, or a
+ *   non-string.
+ */
+export function validateNotEmpty(value: string, label: string): string {
+    if (!value || typeof value !== 'string') {
+        throw new ValidationError(
+            t('error_value_should_not_be_empty', { label }),
+        );
+    }
+    return value;
+}
+
+/**
+ * Collects repeated occurrences of the `--after` CLI option, validating each
+ * target unit name and returning the aggregated list.
+ *
+ * The validation performed here is intentionally minimal – it merely checks
+ * that the argument is a non-empty string. Detailed identifier rules (ASCII
+ * characters, digits, etc.) are enforced elsewhere by
+ * {@link validateIdentifier} when appropriate.
+ *
+ * @param value - Unit name provided with the current `--after` occurrence.
+ * @param previous - Accumulated array of unit names (defaults to an empty
+ *   array).
+ * @returns An array containing all validated `--after` values.
+ *
+ * @throws {ValidationError} If `value` is empty.
+ */
+export function collectAndValidateAfter(
+    value: string,
+    previous: string[] = [],
+): string[] {
+    if (!value || typeof value !== 'string') {
+        throw new ValidationError(
+            t('error_value_should_not_be_empty', { label: '--after' }),
+        );
+    }
+    previous.push(value);
+    return previous;
+}
+
+/**
+ * Validates identifiers used in generated systemd unit file names (e.g.
+ * service or timer names) and option flags like `--run-as`.
+ *
+ * @example
+ * ```ts
+ * validateIdentifier("backup_job", "--name");   // OK
+ * validateIdentifier("foo.bar-baz", "--after"); // OK
+ * validateIdentifier("oops$", "--name");        // throws ValidationError
+ * ```
+ *
+ * @param value - The identifier string to validate.
+ * @param label - The relevant option flag, forwarded to the error message so
+ *   the user immediately sees which argument is wrong.
+ * @returns The unchanged `value` when it satisfies the pattern.
+ *
+ * @throws {ValidationError} If `value` contains characters outside the allowed
+ *   set of ASCII letters, digits, `.`, `_`, and `-`.
+ */
+export function validateIdentifier(value: string, label: string): string {
+    if (!/^[A-Za-z0-9_.-]+$/.test(value)) {
+        throw new ValidationError(
+            t('error_invalid_identifier', { identifier: label, value }),
+        );
+    }
+    return value;
+}
+
+/**
+ * Validates a systemd OnCalendar expression by invoking `systemd-analyze calendar`
+ * as a subprocess using a synchronous call. This avoids async overhead.
+ *
+ * @remarks
+ * Requires a Linux environment with systemd available.
+ *
+ * @param value - Calendar expression to validate
+ * @returns The original `value` if valid
+ * @throws {ValidationError} If the expression is invalid or systemd rejects it
+ */
+export function validateSystemdCalendar(value: string): string {
+    const command = new Deno.Command('systemd-analyze', {
+        args: ['calendar', value],
+        stdout: 'null',
+        stderr: 'null',
+    });
+
+    const { success } = command.outputSync();
+
+    if (!success) {
+        throw new ValidationError(
+            t('error_invalid_calendar', { value }),
+        );
+    }
+
+    return value;
+}
--- a/src/utils/fs.ts
+++ b/src/utils/fs.ts
@@ -1,6 +1,7 @@
 import { ensureDir, exists } from 'https://deno.land/std@0.224.0/fs/mod.ts';
 import { join } from 'https://deno.land/std@0.224.0/path/mod.ts';
 import { TimerOptions } from '../types/mod.ts';
+import { t } from '../i18n/mod.ts';

 export async function writeUnitFiles(
    name: string,
@@ -28,9 +29,9 @@ export async function writeUnitFiles(
                await Deno.remove(timerPath);
            }
        } catch (rollbackError) {
-            console.error('Rollback fehlgeschlagen:', rollbackError);
+            console.error(t('rollback_failed'), rollbackError);
        }
-        console.error('Fehler beim Schreiben der Units:', error);
+        console.error(t('error_write_units'), error);
        return undefined;
    }

--- a/src/utils/mod.ts
+++ b/src/utils/mod.ts
@@ -1,3 +1,11 @@
+export {
+    collectAndValidateAfter,
+    collectAndValidateEnv,
+    validateIdentifier,
+    validateNotEmpty,
+    validatePath,
+    validateSystemdCalendar,
+} from './cliValidationHelper.ts';
 export { resolveUnitTargetPath, writeUnitFiles } from './fs.ts';
 export { deriveNameFromExec } from './misc.ts';
 export { getVersion } from './version.ts';
@@ -1 +1 @@
 .2.0
 .5.1
				`@@ -0,0 +1 @@`
				`export { getCurrentLanguage, initI18n, loadLocale, t } from './i18n.ts';`