feat: add optional variadic args to all commands

Allow callers to pass additional systemctl flags (e.g. --no-block,
--force) via variadic string args on every exported function.

This is backward-compatible: existing callers without extra args
continue to work unchanged.

Introduces a prepareArgs helper to centralize argument construction,
replacing the duplicated args/UserMode pattern across all functions.

Closes #2

.github/workflows/ci.yml

@@ -1,65 +0,0 @@
-name: CI
-
-on:
-  push:
-    branches: [master]
-  pull_request:
-    branches: [master]
-
-permissions:
-  contents: read
-
-jobs:
-  test:
-    name: Test (Go ${{ matrix.go-version }})
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        go-version: ["1.26"]
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Set up Go ${{ matrix.go-version }}
-        uses: actions/setup-go@v5
-        with:
-          go-version: ${{ matrix.go-version }}
-          cache: true
-
-      - name: Install and start nginx
-        run: |
-          sudo apt-get update -qq
-          sudo apt-get install -y -qq nginx
-          sudo systemctl start nginx
-          sudo systemctl enable nginx
-
-      - name: Run tests (user)
-        run: go test -race -coverprofile=coverage-user.out -covermode=atomic ./...
-
-      - name: Run tests (root)
-        run: sudo go test -race -coverprofile=coverage-root.out -covermode=atomic ./...
-
-      - name: Upload coverage to Codecov
-        if: matrix.go-version == '1.26'
-        uses: codecov/codecov-action@v5
-        with:
-          files: coverage-user.out,coverage-root.out
-          token: ${{ secrets.CODECOV_TOKEN }}
-          fail_ci_if_error: false
-
-  lint:
-    name: Lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Set up Go
-        uses: actions/setup-go@v5
-        with:
-          go-version: "1.26"
-          cache: true
-
-      - name: Run staticcheck
-        uses: dominikh/staticcheck-action@v1
-        with:
-          version: latest
-          install-go: false

filtererr_test.go

@@ -1,134 +0,0 @@
-package systemctl
-
-import (
-	"errors"
-	"testing"
-)
-
-func TestFilterErr(t *testing.T) {
-	tests := []struct {
-		name   string
-		stderr string
-		want   error
-	}{
-		{
-			name:   "empty stderr",
-			stderr: "",
-			want:   nil,
-		},
-		{
-			name:   "unit does not exist",
-			stderr: "Unit foo.service does not exist, proceeding anyway.",
-			want:   ErrDoesNotExist,
-		},
-		{
-			name:   "unit not found",
-			stderr: "Unit foo.service not found.",
-			want:   ErrDoesNotExist,
-		},
-		{
-			name:   "unit not loaded",
-			stderr: "Unit foo.service not loaded.",
-			want:   ErrUnitNotLoaded,
-		},
-		{
-			name:   "no such file or directory",
-			stderr: "No such file or directory",
-			want:   ErrDoesNotExist,
-		},
-		{
-			name:   "interactive authentication required",
-			stderr: "Interactive authentication required.",
-			want:   ErrInsufficientPermissions,
-		},
-		{
-			name:   "access denied",
-			stderr: "Access denied",
-			want:   ErrInsufficientPermissions,
-		},
-		{
-			name:   "dbus session bus address",
-			stderr: "Failed to connect to bus: $DBUS_SESSION_BUS_ADDRESS not set",
-			want:   ErrBusFailure,
-		},
-		{
-			name:   "unit is masked",
-			stderr: "Unit foo.service is masked.",
-			want:   ErrMasked,
-		},
-		{
-			name:   "generic failed",
-			stderr: "Failed to do something unknown",
-			want:   ErrUnspecified,
-		},
-		{
-			name:   "does not exist with auth required prioritizes permission error",
-			stderr: "Unit nginx.service does not exist, proceeding anyway.\nFailed to mask unit: Interactive authentication required.",
-			want:   ErrInsufficientPermissions,
-		},
-		{
-			name:   "does not exist with access denied prioritizes permission error",
-			stderr: "Unit foo.service does not exist, proceeding anyway.\nAccess denied",
-			want:   ErrInsufficientPermissions,
-		},
-		{
-			name:   "does not exist with bus failure prioritizes bus error",
-			stderr: "Unit foo.service does not exist, proceeding anyway.\n$DBUS_SESSION_BUS_ADDRESS not set",
-			want:   ErrBusFailure,
-		},
-		{
-			name:   "unrecognized warning",
-			stderr: "Warning: something benign happened",
-			want:   nil,
-		},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			got := filterErr(tt.stderr)
-			if tt.want == nil {
-				if got != nil {
-					t.Errorf("filterErr(%q) = %v, want nil", tt.stderr, got)
-				}
-				return
-			}
-			if !errors.Is(got, tt.want) {
-				t.Errorf("filterErr(%q) = %v, want error wrapping %v", tt.stderr, got, tt.want)
-			}
-		})
-	}
-}
-
-func TestHasValidUnitSuffix(t *testing.T) {
-	tests := []struct {
-		unit string
-		want bool
-	}{
-		{"nginx.service", true},
-		{"sshd.socket", true},
-		{"backup.timer", true},
-		{"dev-sda1.device", true},
-		{"home.mount", true},
-		{"dev-sda1.swap", true},
-		{"user.slice", true},
-		{"multi-user.target", true},
-		{"session-1.scope", true},
-		{"foo.automount", true},
-		{"backup.path", true},
-		{"foo.snapshot", true},
-		{"nginx", false},
-		{"", false},
-		{"foo.bar", false},
-		{"foo.services", false},
-		{".service", true},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.unit, func(t *testing.T) {
-			got := HasValidUnitSuffix(tt.unit)
-			if got != tt.want {
-				t.Errorf("HasValidUnitSuffix(%q) = %v, want %v", tt.unit, got, tt.want)
-			}
-		})
-	}
-}

go.mod

@@ -1,3 +1,3 @@
 module github.com/taigrr/systemctl
 
-go 1.26.1
+go 1.26

helpers.go

@@ -32,23 +32,7 @@ func GetNumRestarts(ctx context.Context, unit string, opts Options) (int, error)
 	if err != nil {
 		return -1, err
 	}
-	if value == "[not set]" {
-		return -1, ErrValueNotSet
-	}
-	restarts, err := strconv.Atoi(value)
-	if err != nil {
-		return -1, err
-	}
-	// systemd returns NRestarts=0 for both genuinely zero-restart units and
-	// nonexistent/unloaded units. Disambiguate by checking LoadState: if the
-	// unit isn't loaded, the value is meaningless.
-	if restarts == 0 {
-		loadState, loadErr := Show(ctx, unit, properties.LoadState, opts)
-		if loadErr == nil && loadState == "not-found" {
-			return -1, ErrValueNotSet
-		}
-	}
-	return restarts, nil
+	return strconv.Atoi(value)
 }
 
 // Get current memory in bytes (`systemctl show [unit] --property MemoryCurrent`) as an int

helpers_test.go

@@ -105,8 +105,8 @@ func TestGetNumRestarts(t *testing.T) {
 
 		// try nonexistant unit in user mode as user
 		{"nonexistant", ErrValueNotSet, Options{UserMode: false}, true},
-		// try existing unit in user mode as user (loaded, so NRestarts=0 is valid)
-		{"syncthing", nil, Options{UserMode: true}, true},
+		// try existing unit in user mode as user
+		{"syncthing", ErrValueNotSet, Options{UserMode: true}, true},
 		// try existing unit in system mode as user
 		{"nginx", nil, Options{UserMode: false}, true},
 

systemctl_test.go

@@ -290,7 +290,7 @@ func TestMask(t *testing.T) {
 		// try existing unit in user mode as user
 		{"syncthing", nil, Options{UserMode: true}, true},
 		// try nonexisting unit in system mode as user
-		{"nonexistant", ErrInsufficientPermissions, Options{UserMode: false}, true},
+		{"nonexistant", ErrDoesNotExist, Options{UserMode: false}, true},
 		// try existing unit in system mode as user
 		{"nginx", ErrInsufficientPermissions, Options{UserMode: false}, true},
 
@@ -521,7 +521,7 @@ func TestUnmask(t *testing.T) {
 		// try existing unit in user mode as user
 		{"syncthing", nil, Options{UserMode: true}, true},
 		// try nonexisting unit in system mode as user
-		{"nonexistant", ErrInsufficientPermissions, Options{UserMode: false}, true},
+		{"nonexistant", ErrDoesNotExist, Options{UserMode: false}, true},
 		// try existing unit in system mode as user
 		{"nginx", ErrInsufficientPermissions, Options{UserMode: false}, true},
 

util.go

@@ -70,21 +70,7 @@ func prepareArgs(base string, opts Options, extra ...string) []string {
 }
 
 func filterErr(stderr string) error {
-	// Order matters: check higher-priority errors first.
-	// For example, `systemctl mask nginx` as a non-root user on a system
-	// without nginx prints both "does not exist, proceeding anyway" (a
-	// warning) and "Interactive authentication required" (the real error).
-	// Permission and bus errors must be checked before "does not exist" so
-	// the actual failure reason is returned.
 	switch {
-	case strings.Contains(stderr, `Interactive authentication required`):
-		return errors.Join(ErrInsufficientPermissions, fmt.Errorf("stderr: %s", stderr))
-	case strings.Contains(stderr, `Access denied`):
-		return errors.Join(ErrInsufficientPermissions, fmt.Errorf("stderr: %s", stderr))
-	case strings.Contains(stderr, `DBUS_SESSION_BUS_ADDRESS`):
-		return errors.Join(ErrBusFailure, fmt.Errorf("stderr: %s", stderr))
-	case strings.Contains(stderr, `is masked`):
-		return errors.Join(ErrMasked, fmt.Errorf("stderr: %s", stderr))
 	case strings.Contains(stderr, `does not exist`):
 		return errors.Join(ErrDoesNotExist, fmt.Errorf("stderr: %s", stderr))
 	case strings.Contains(stderr, `not found.`):
@@ -93,6 +79,14 @@ func filterErr(stderr string) error {
 		return errors.Join(ErrUnitNotLoaded, fmt.Errorf("stderr: %s", stderr))
 	case strings.Contains(stderr, `No such file or directory`):
 		return errors.Join(ErrDoesNotExist, fmt.Errorf("stderr: %s", stderr))
+	case strings.Contains(stderr, `Interactive authentication required`):
+		return errors.Join(ErrInsufficientPermissions, fmt.Errorf("stderr: %s", stderr))
+	case strings.Contains(stderr, `Access denied`):
+		return errors.Join(ErrInsufficientPermissions, fmt.Errorf("stderr: %s", stderr))
+	case strings.Contains(stderr, `DBUS_SESSION_BUS_ADDRESS`):
+		return errors.Join(ErrBusFailure, fmt.Errorf("stderr: %s", stderr))
+	case strings.Contains(stderr, `is masked`):
+		return errors.Join(ErrMasked, fmt.Errorf("stderr: %s", stderr))
 	case strings.Contains(stderr, `Failed`):
 		return errors.Join(ErrUnspecified, fmt.Errorf("stderr: %s", stderr))
 	default: