Support environment variables in commands

command.go

@@ -32,19 +32,25 @@ import (
 
 type command []string
 
-func (c *command) process(dir string, flags int) error {
-	if len(*c) < 1 {
+func (c command) expandEnv() {
+	for index, value := range c {
+		c[index] = os.ExpandEnv(value)
+	}
+}
+
+func (c command) process(dir string, flags int) error {
+	if len(c) < 1 {
 		return fmt.Errorf("command element is invalid")
 	}
 
-	cmd := exec.Command((*c)[0], (*c)[1:]...)
+	cmd := exec.Command(c[0], c[1:]...)
 	cmd.Dir = dir
 	cmd.Stderr = os.Stderr
 	cmd.Stdout = os.Stdout
 	cmd.Stdin = os.Stdin
 
 	if flags&flagVerbose == flagVerbose {
-		log.Printf("executing command %s", strings.Join(*c, " "))
+		log.Printf("executing command %s", strings.Join(c, " "))
 	}
 
 	return cmd.Run()

link.go

@@ -72,32 +72,35 @@ func createPath(loc string, flags int, mode os.FileMode) error {
 	return nil
 }
 
-func (l *link) parse() (string, string, os.FileMode, error) {
-	length := len(*l)
+func (l link) parse() (srcPath string, dstPath string, mode os.FileMode, err error) {
+	length := len(l)
 	if length < 1 || length > 3 {
-		return "", "", 0, fmt.Errorf("link element is invalid")
+		err = fmt.Errorf("link element is invalid")
+		return
 	}
 
-	dstPath := (*l)[0]
-	srcPath := dstPath
-	if length > 1 {
-		srcPath = (*l)[1]
-	}
-
-	var mode os.FileMode = 0755
 	if length > 2 {
-		parsed, err := strconv.ParseUint((*l)[2], 0, 64)
+		var parsed uint64
+		parsed, err = strconv.ParseUint(l[2], 0, 64)
 		if err != nil {
-			return "", "", 0, err
+			return
 		}
 
 		mode = os.FileMode(parsed)
+	} else {
+		mode = 0755
 	}
 
-	return srcPath, dstPath, mode, nil
+	dstPath = os.ExpandEnv(l[0])
+	srcPath = dstPath
+	if length > 1 {
+		srcPath = os.ExpandEnv(l[1])
 	}
 
-func (l *link) process(srcDir, dstDir string, flags int) error {
+	return
+}
+
+func (l link) process(srcDir, dstDir string, flags int) error {
 	srcPath, dstPath, mode, err := l.parse()
 	if err != nil {
 		return err