add copy command (instruction)

internal/instruction/copy.go

@@ -0,0 +1,47 @@
+package instruction
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+type copy struct {
+	raw string
+	Src string
+	Dst string
+}
+
+func (d *copy) Raw() string { return strings.Join([]string{"copy", d.raw}, " ") }
+
+func (d *copy) Build(_args string) error {
+
+	// 1. extract action (sub command)
+	split := strings.Split(_args, " ")
+
+	// 2. check syntax
+	if len(split) != 2 {
+		return ErrInvalidSyntax
+	}
+
+	d.Src = strings.Trim(split[0], " \t")
+	d.Dst = strings.Trim(split[1], " \t")
+	d.raw = _args
+	return nil
+}
+
+func (d copy) Exec(ctx ExecutionContext) ([]byte, error) {
+
+	// 1. fail if source file not found
+	if _, err := os.Stat(d.Src); os.IsNotExist(err) {
+		return nil, fmt.Errorf("cannot find script '%s'", d.Src)
+	}
+
+	// 2. execute script
+	if err := ctx.Executor.Command("cp", d.Src, d.Dst).Run(); err != nil {
+		return nil, fmt.Errorf("cannot copy '%s' to '%s' | %s", d.Src, d.Dst, err)
+	}
+
+	return nil, nil
+
+}

internal/instruction/reader.go

@@ -40,6 +40,10 @@ func Parse(raw string) (T, error) {
 		i := &set{}
 		err := i.Build(split[1])
 		return i, err
+	case "copy":
+		i := &copy{}
+		err := i.Build(split[1])
+		return i, err
 	case "alias":
 		i := &alias{}
 		err := i.Build(split[1])