Merge pull request #10 from guonaihong/env

env: done

README.md

@@ -36,6 +36,7 @@ If you want to use the cat command
 * dirname [detail](./dirname/README.md)
 * echo [detail](./echo/README.md)
 * head [detail](./head/README.md)
+* env
 * link 
 * md5sum [detail](./md5sum/README.md)
 * paste [detail](./paste/README.md)
@@ -62,4 +63,4 @@ If you want to use the cat command
 * sleep [detail](./sleep/README.md)
 
 ## progress
-progress = 33 / 92 = 35%
+progress = 34 / 92 = 36.7%

coreutils/coreutils.go

@@ -10,6 +10,7 @@ import (
 	"github.com/guonaihong/coreutils/cut"
 	"github.com/guonaihong/coreutils/dirname"
 	"github.com/guonaihong/coreutils/echo"
+	"github.com/guonaihong/coreutils/env"
 	"github.com/guonaihong/coreutils/head"
 	"github.com/guonaihong/coreutils/link"
 	"github.com/guonaihong/coreutils/md5sum"
@@ -90,6 +91,10 @@ func main() {
 		echo.Main(os.Args[1:])
 	})
 
+	parent.SubCommand("env", "Use the env subcommand", func() {
+		env.Main(os.Args[1:])
+	})
+
 	parent.SubCommand("head", "Use the head subcommand", func() {
 		head.Main(os.Args[1:])
 	})

env/env.go

@@ -0,0 +1,60 @@
+package env
+
+import (
+	"fmt"
+	"github.com/guonaihong/flag"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+type Env struct {
+	IgnoreEnvironment bool   `opt:"i, ignore-environment" usage:"start with an empty environment"`
+	Unset             string `opt:"u, unset" usage:"remove variable from the environment"`
+	//Chdir             string `opt:"C, chdir" usage:"change working directory to DIR"`
+	Null bool `opt:"0, null" usage:"end each output line with NUL, not newline"`
+}
+
+func Main(argv []string) {
+	var env Env
+	delimiter := byte('\n')
+
+	command := flag.NewFlagSet(argv[0], flag.ExitOnError)
+	command.ParseStruct(argv[1:], &env)
+	args := command.Args()
+
+	if env.IgnoreEnvironment {
+		os.Clearenv()
+	}
+
+	if env.Null {
+		delimiter = byte(0)
+	}
+
+	for k, v := range args {
+		if strings.IndexByte(v, '=') > 0 {
+			kv := strings.SplitN(v, "=", 2)
+			if err := os.Setenv(kv[0], kv[1]); err != nil {
+				fmt.Printf("%s\n", err)
+			}
+			continue
+		}
+
+		cmd := exec.Command(args[k], args[k+1:]...)
+		cmd.Stdout = os.Stdout
+		cmd.Stdin = os.Stdin
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			fmt.Printf("%s\n", err)
+			os.Exit(1)
+		}
+
+		os.Exit(0)
+	}
+
+	allArgs := os.Environ()
+	for _, v := range allArgs {
+		fmt.Fprintf(os.Stdout, "%s%c", v, delimiter)
+	}
+}