Add unit reload support

Author: taigrr

README.md

@@ -22,6 +22,7 @@ If your system isn't running (or targeting another system running) `systemctl`,
 - [x] `systemctl is-enabled`
 - [x] `systemctl is-failed`
 - [x] `systemctl mask`
+- [x] `systemctl reload`
 - [x] `systemctl restart`
 - [x] `systemctl show`
 - [x] `systemctl start`

reload_linux_test.go

@@ -0,0 +1,67 @@
+//go:build linux
+
+package systemctl
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestReloadBuildsExpectedCommand(t *testing.T) {
+	tests := []struct {
+		name string
+		opts Options
+		want []string
+	}{
+		{
+			name: "system mode",
+			opts: Options{},
+			want: []string{"reload", "--system", "nginx.service"},
+		},
+		{
+			name: "user mode",
+			opts: Options{UserMode: true},
+			want: []string{"reload", "--user", "nginx.service"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tempDir := t.TempDir()
+			logFile := filepath.Join(tempDir, "args.log")
+			fakeSystemctl := filepath.Join(tempDir, "systemctl")
+			script := "#!/bin/sh\nprintf '%s\\n' \"$@\" > '" + logFile + "'\n"
+
+			if err := os.WriteFile(fakeSystemctl, []byte(script), 0o755); err != nil {
+				t.Fatalf("write fake systemctl: %v", err)
+			}
+
+			original := systemctl
+			systemctl = fakeSystemctl
+			t.Cleanup(func() {
+				systemctl = original
+			})
+
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+			defer cancel()
+
+			if err := Reload(ctx, "nginx.service", tt.opts); err != nil {
+				t.Fatalf("Reload returned error: %v", err)
+			}
+
+			gotBytes, err := os.ReadFile(logFile)
+			if err != nil {
+				t.Fatalf("read captured args: %v", err)
+			}
+			got := strings.Fields(strings.TrimSpace(string(gotBytes)))
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("Reload args = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

systemctl.go

@@ -104,6 +104,13 @@ func Restart(ctx context.Context, unit string, opts Options, args ...string) err
 	return restart(ctx, unit, opts, args...)
 }
 
+// Reload one or more units if they support reload.
+//
+// Any additional arguments are passed directly to the systemctl command.
+func Reload(ctx context.Context, unit string, opts Options, args ...string) error {
+	return reload(ctx, unit, opts, args...)
+}
+
 // Show a selected property of a unit. Accepted properties are predefined in the
 // properties subpackage to guarantee properties are valid and assist code-completion.
 //

systemctl_darwin.go

@@ -44,6 +44,10 @@ func restart(_ context.Context, _ string, _ Options, _ ...string) error {
 	return nil
 }
 
+func reload(_ context.Context, _ string, _ Options, _ ...string) error {
+	return nil
+}
+
 func show(_ context.Context, _ string, _ properties.Property, _ Options, _ ...string) (string, error) {
 	return "", nil
 }

systemctl_linux.go

@@ -115,6 +115,12 @@ func restart(ctx context.Context, unit string, opts Options, args ...string) err
 	return err
 }
 
+func reload(ctx context.Context, unit string, opts Options, args ...string) error {
+	a := prepareArgs("reload", opts, append([]string{unit}, args...)...)
+	_, _, _, err := execute(ctx, a)
+	return err
+}
+
 func show(ctx context.Context, unit string, property properties.Property, opts Options, args ...string) (string, error) {
 	extra := append([]string{unit, "--property", string(property)}, args...)
 	a := prepareArgs("show", opts, extra...)