refactor: clean up unused code, fix typos, improve docs

- Remove unused 'killed' const and 'unitTypes' var (staticcheck U1000)
- Replace regexp with strings.TrimSuffix+switch in isFailed for consistency
- Fix typo: 'programatically' -> 'programmatically'
- Fix typo: 'an an int' -> 'as an int' in README and helpers.go
- Add missing godoc comments on exported helper functions
- Bump minimum Go version from 1.18 to 1.21

README.md

@@ -32,7 +32,7 @@ If your system isn't running (or targeting another system running) `systemctl`,
 ## Helper functionality
 
 - [x] Get start time of a service (`ExecMainStartTimestamp`) as a `Time` type
-- [x] Get current memory in bytes (`MemoryCurrent`) an an int
+- [x] Get current memory in bytes (`MemoryCurrent`) as an int
 - [x] Get the PID of the main process (`MainPID`) as an int
 - [x] Get the restart count of a unit (`NRestarts`) as an int
 

go.mod

@@ -1,3 +1,3 @@
 module github.com/taigrr/systemctl
 
-go 1.18
+go 1.21

helpers.go

@@ -35,7 +35,7 @@ func GetNumRestarts(ctx context.Context, unit string, opts Options) (int, error)
 	return strconv.Atoi(value)
 }
 
-// Get current memory in bytes (`systemctl show [unit] --property MemoryCurrent`) an an int
+// Get current memory in bytes (`systemctl show [unit] --property MemoryCurrent`) as an int
 func GetMemoryUsage(ctx context.Context, unit string, opts Options) (int, error) {
 	value, err := Show(ctx, unit, properties.MemoryCurrent, opts)
 	if err != nil {
@@ -56,6 +56,7 @@ func GetPID(ctx context.Context, unit string, opts Options) (int, error) {
 	return strconv.Atoi(value)
 }
 
+// GetSocketsForServiceUnit returns the socket units associated with a given service unit.
 func GetSocketsForServiceUnit(ctx context.Context, unit string, opts Options) ([]string, error) {
 	args := []string{"list-sockets", "--all", "--no-legend", "--no-pager"}
 	if opts.UserMode {
@@ -81,6 +82,7 @@ func GetSocketsForServiceUnit(ctx context.Context, unit string, opts Options) ([
 	return sockets, nil
 }
 
+// GetUnits returns a list of all loaded units and their states.
 func GetUnits(ctx context.Context, opts Options) ([]Unit, error) {
 	args := []string{"list-units", "--all", "--no-legend", "--full", "--no-pager"}
 	if opts.UserMode {
@@ -109,6 +111,7 @@ func GetUnits(ctx context.Context, opts Options) ([]Unit, error) {
 	return units, nil
 }
 
+// GetMaskedUnits returns a list of all masked unit names.
 func GetMaskedUnits(ctx context.Context, opts Options) ([]string, error) {
 	args := []string{"list-unit-files", "--state=masked"}
 	if opts.UserMode {
@@ -138,7 +141,7 @@ func GetMaskedUnits(ctx context.Context, opts Options) ([]string, error) {
 	return units, nil
 }
 
-// check if systemd is the current init system
+// IsSystemd checks if systemd is the current init system by reading /proc/1/comm.
 func IsSystemd() (bool, error) {
 	b, err := os.ReadFile("/proc/1/comm")
 	if err != nil {
@@ -147,7 +150,7 @@ func IsSystemd() (bool, error) {
 	return strings.TrimSpace(string(b)) == "systemd", nil
 }
 
-// check if a service is masked
+// IsMasked checks if a unit is masked.
 func IsMasked(ctx context.Context, unit string, opts Options) (bool, error) {
 	units, err := GetMaskedUnits(ctx, opts)
 	if err != nil {
@@ -161,8 +164,8 @@ func IsMasked(ctx context.Context, unit string, opts Options) (bool, error) {
 	return false, nil
 }
 
-// check if a service is running
+// IsRunning checks if a unit's sub-state is "running".
-// https://unix.stackexchange.com/a/396633
+// See https://unix.stackexchange.com/a/396633 for details.
 func IsRunning(ctx context.Context, unit string, opts Options) (bool, error) {
 	status, err := Show(ctx, unit, properties.SubState, opts)
 	return status == "running", err

structs.go

@@ -11,18 +11,3 @@ type Unit struct {
 	Sub         string
 	Description string
 }
-
-var unitTypes = []string{
-	"automount",
-	"device",
-	"mount",
-	"path",
-	"scope",
-	"service",
-	"slice",
-	"snapshot",
-	"socket",
-	"swap",
-	"target",
-	"timer",
-}

systemctl.go

@@ -104,7 +104,7 @@ func Start(ctx context.Context, unit string, opts Options) error {
 // Get back the status string which would be returned by running
 // `systemctl status [unit]`.
 //
-// Generally, it makes more sense to programatically retrieve the properties
+// Generally, it makes more sense to programmatically retrieve the properties
 // using Show, but this command is provided for the sake of completeness
 func Status(ctx context.Context, unit string, opts Options) (string, error) {
 	stat, err := status(ctx, unit, opts)

systemctl_linux.go

@@ -4,7 +4,6 @@ package systemctl
 
 import (
 	"context"
-	"regexp"
 	"strings"
 
 	"github.com/taigrr/systemctl/properties"
@@ -148,15 +147,18 @@ func isFailed(ctx context.Context, unit string, opts Options) (bool, error) {
 		args[1] = "--user"
 	}
 	stdout, _, _, err := execute(ctx, args)
-	if matched, _ := regexp.MatchString(`inactive`, stdout); matched {
+	stdout = strings.TrimSuffix(stdout, "\n")
+	switch stdout {
+	case "inactive":
 		return false, nil
-	} else if matched, _ := regexp.MatchString(`active`, stdout); matched {
+	case "active":
 		return false, nil
-	} else if matched, _ := regexp.MatchString(`failed`, stdout); matched {
+	case "failed":
 		return true, nil
-	}
+	default:
 		return false, err
 	}
+}
 
 // Mask one or more units, as specified on the command line. This will link
 // these unit files to /dev/null, making it impossible to start them.
@@ -210,7 +212,7 @@ func start(ctx context.Context, unit string, opts Options) error {
 // Get back the status string which would be returned by running
 // `systemctl status [unit]`.
 //
-// Generally, it makes more sense to programatically retrieve the properties
+// Generally, it makes more sense to programmatically retrieve the properties
 // using Show, but this command is provided for the sake of completeness
 func status(ctx context.Context, unit string, opts Options) (string, error) {
 	args := []string{"status", "--system", unit}

util.go

@@ -11,8 +11,6 @@ import (
 
 var systemctl string
 
-const killed = 130
-
 func init() {
 	path, _ := exec.LookPath("systemctl")
 	systemctl = path