feat: Add ability to run commands at given path

sh/cmd.go

@@ -16,19 +16,19 @@ import (
 // useful for creating command aliases to make your scripts easier to read, like
 // this:
 //
-//  // in a helper file somewhere
-//  var g0 = sh.RunCmd("go")  // go is a keyword :(
+//	 // in a helper file somewhere
+//	 var g0 = sh.RunCmd("go")  // go is a keyword :(
 //
-//  // somewhere in your main code
-//	if err := g0("install", "github.com/gohugo/hugo"); err != nil {
-//		return err
-//  }
+//	 // somewhere in your main code
+//		if err := g0("install", "github.com/gohugo/hugo"); err != nil {
+//			return err
+//	 }
 //
 // Args passed to command get baked in as args to the command when you run it.
 // Any args passed in when you run the returned function will be appended to the
 // original args.  For example, this is equivalent to the above:
 //
-//  var goInstall = sh.RunCmd("go", "install") goInstall("github.com/gohugo/hugo")
+//	var goInstall = sh.RunCmd("go", "install") goInstall("github.com/gohugo/hugo")
 //
 // RunCmd uses Exec underneath, so see those docs for more details.
 func RunCmd(cmd string, args ...string) func(args ...string) error {
@@ -37,6 +37,31 @@ func RunCmd(cmd string, args ...string) func(args ...string) error {
 	}
 }
 
+// RunAtCmd returns a function that will call Run with the given command at a given path.
+// This is useful for creating command aliases to make your scripts easier to read, like
+// this:
+//
+//	 // in a helper file somewhere
+//	 var g0 = sh.RunAtCmd("go")  // go is a keyword :(
+//
+//	 // somewhere in your main code
+//		if err := g0("/tmp", "install", "github.com/gohugo/hugo"); err != nil {
+//			return err
+//	 }
+//
+// Args passed to command get baked in as args to the command when you run it.
+// Any args passed in when you run the returned function will be appended to the
+// original args.  For example, this is equivalent to the above:
+//
+//	var goInstall = sh.RunAtCmd("go", "install") goInstall("tmp", "github.com/gohugo/hugo")
+//
+// RunAtCmd uses Exec underneath, so see those docs for more details.
+func RunAtCmd(cmd string, args ...string) func(pwd string, args ...string) error {
+	return func(pwd string, args2 ...string) error {
+		return RunAt(pwd, cmd, append(args, args2...)...)
+	}
+}
+
 // OutCmd is like RunCmd except the command returns the output of the
 // command.
 func OutCmd(cmd string, args ...string) func(args ...string) (string, error) {
@@ -45,14 +70,32 @@ func OutCmd(cmd string, args ...string) func(args ...string) (string, error) {
 	}
 }
 
+// OutAtCmd is like RunAtCmd except the command returns the output of the
+// command.
+func OutAtCmd(cmd string, args ...string) func(pwd string, args ...string) (string, error) {
+	return func(pwd string, args2 ...string) (string, error) {
+		return OutputAt(pwd, cmd, append(args, args2...)...)
+	}
+}
+
 // Run is like RunWith, but doesn't specify any environment variables.
 func Run(cmd string, args ...string) error {
 	return RunWith(nil, cmd, args...)
 }
 
+// RunAt is like RunAtWith, but doesn't specify any environment variables.
+func RunAt(pwd, cmd string, args ...string) error {
+	return RunAtWith(nil, pwd, cmd, args...)
+}
+
 // RunV is like Run, but always sends the command's stdout to os.Stdout.
 func RunV(cmd string, args ...string) error {
-	_, err := Exec(nil, os.Stdout, os.Stderr, cmd, args...)
+	return RunAtV("", cmd, args...)
+}
+
+// RunAtV is like RunAt, but always sends the command's stdout to os.Stdout.
+func RunAtV(pwd string, cmd string, args ...string) error {
+	_, err := ExecAt(nil, os.Stdout, os.Stderr, pwd, cmd, args...)
 	return err
 }
 
@@ -61,35 +104,63 @@ func RunV(cmd string, args ...string) error {
 // environment variables for the command being run. Environment variables should
 // be in the format name=value.
 func RunWith(env map[string]string, cmd string, args ...string) error {
+	return RunAtWith(env, "", cmd, args...)
+}
+
+// RunAtWith runs the given command at a certain path, directing stderr to this
+// program's stderr and printing stdout to stdout if mage was run with -v.  It adds
+// adds env to the environment variables for the command being run. Environment
+// variables should be in the format name=value.
+func RunAtWith(env map[string]string, pwd string, cmd string, args ...string) error {
 	var output io.Writer
 	if mg.Verbose() {
 		output = os.Stdout
 	}
-	_, err := Exec(env, output, os.Stderr, cmd, args...)
+	_, err := ExecAt(env, output, os.Stderr, pwd, cmd, args...)
 	return err
 }
 
 // RunWithV is like RunWith, but always sends the command's stdout to os.Stdout.
 func RunWithV(env map[string]string, cmd string, args ...string) error {
-	_, err := Exec(env, os.Stdout, os.Stderr, cmd, args...)
+	return RunAtWithV(env, "", cmd, args...)
+}
+
+// RunAtWithV is like RunAtWith, but always sends the command's stdout to os.Stdout.
+func RunAtWithV(env map[string]string, pwd string, cmd string, args ...string) error {
+	_, err := ExecAt(env, os.Stdout, os.Stderr, pwd, cmd, args...)
 	return err
 }
 
 // Output runs the command and returns the text from stdout.
 func Output(cmd string, args ...string) (string, error) {
+	return OutputAt("", cmd, args...)
+}
+
+// OutputAt runs the command at a certain path and returns the text from stdout.
+func OutputAt(pwd string, cmd string, args ...string) (string, error) {
 	buf := &bytes.Buffer{}
-	_, err := Exec(nil, buf, os.Stderr, cmd, args...)
+	_, err := ExecAt(nil, buf, os.Stderr, pwd, cmd, args...)
 	return strings.TrimSuffix(buf.String(), "\n"), err
 }
 
 // OutputWith is like RunWith, but returns what is written to stdout.
 func OutputWith(env map[string]string, cmd string, args ...string) (string, error) {
+	return OutputAtWith(env, "", cmd, args...)
+}
+
+// OutputAt	With is like RunAtWith, but returns what is written to stdout.
+func OutputAtWith(env map[string]string, pwd string, cmd string, args ...string) (string, error) {
 	buf := &bytes.Buffer{}
-	_, err := Exec(env, buf, os.Stderr, cmd, args...)
+	_, err := ExecAt(env, buf, os.Stderr, pwd, cmd, args...)
 	return strings.TrimSuffix(buf.String(), "\n"), err
 }
 
-// Exec executes the command, piping its stdout and stderr to the given
+// Exec is like execAt but always runs in the current workdir.
+func Exec(env map[string]string, stdout, stderr io.Writer, cmd string, args ...string) (ran bool, err error) {
+	return ExecAt(env, stdout, stderr, "", cmd, args...)
+}
+
+// ExecAt executes the command, piping its stdout and stderr to the given
 // writers. If the command fails, it will return an error that, if returned
 // from a target or mg.Deps call, will cause mage to exit with the same code as
 // the command failed with. Env is a list of environment variables to set when
@@ -101,7 +172,8 @@ func OutputWith(env map[string]string, cmd string, args ...string) (string, erro
 // Ran reports if the command ran (rather than was not found or not executable).
 // Code reports the exit code the command returned if it ran. If err == nil, ran
 // is always true and code is always 0.
-func Exec(env map[string]string, stdout, stderr io.Writer, cmd string, args ...string) (ran bool, err error) {
+
+func ExecAt(env map[string]string, stdout, stderr io.Writer, pwd string, cmd string, args ...string) (ran bool, err error) {
 	expand := func(s string) string {
 		s2, ok := env[s]
 		if ok {
@@ -113,7 +185,7 @@ func Exec(env map[string]string, stdout, stderr io.Writer, cmd string, args ...s
 	for i := range args {
 		args[i] = os.Expand(args[i], expand)
 	}
-	ran, code, err := run(env, stdout, stderr, cmd, args...)
+	ran, code, err := run(env, stdout, stderr, pwd, cmd, args...)
 	if err == nil {
 		return true, nil
 	}
@@ -123,19 +195,20 @@ func Exec(env map[string]string, stdout, stderr io.Writer, cmd string, args ...s
 	return ran, fmt.Errorf(`failed to run "%s %s: %v"`, cmd, strings.Join(args, " "), err)
 }
 
-func run(env map[string]string, stdout, stderr io.Writer, cmd string, args ...string) (ran bool, code int, err error) {
+func run(env map[string]string, stdout, stderr io.Writer, pwd string, cmd string, args ...string) (ran bool, code int, err error) {
 	c := exec.Command(cmd, args...)
 	c.Env = os.Environ()
 	for k, v := range env {
 		c.Env = append(c.Env, k+"="+v)
 	}
+	c.Dir = pwd
 	c.Stderr = stderr
 	c.Stdout = stdout
 	c.Stdin = os.Stdin
 
-	var quoted []string 
+	var quoted []string
 	for i := range args {
-		quoted = append(quoted, fmt.Sprintf("%q", args[i]));
+		quoted = append(quoted, fmt.Sprintf("%q", args[i]))
 	}
 	// To protect against logging from doing exec in global variables
 	if mg.Verbose() {
@@ -144,6 +217,7 @@ func run(env map[string]string, stdout, stderr io.Writer, cmd string, args ...st
 	err = c.Run()
 	return CmdRan(err), ExitStatus(err), err
 }
+
 // CmdRan examines the error to determine if it was generated as a result of a
 // command running via os/exec.Command.  If the error is nil, or the command ran
 // (even if it exited with a non-zero exit code), CmdRan reports true.  If the

sh/cmd_test.go

@@ -2,6 +2,7 @@ package sh
 
 import (
 	"bytes"
+	"fmt"
 	"os"
 	"testing"
 )
@@ -18,6 +19,18 @@ func TestOutCmd(t *testing.T) {
 	}
 }
 
+func TestOutAtCmd(t *testing.T) {
+	cmd := OutAtCmd("sh", "-c")
+	out, err := cmd("/", "pwd")
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := "/"
+	if out != expected {
+		t.Fatalf("expected %q but got %q", expected, out)
+	}
+}
+
 func TestExitCode(t *testing.T) {
 	ran, err := Exec(nil, nil, nil, os.Args[0], "-helper", "-exit", "99")
 	if err == nil {
@@ -68,5 +81,46 @@ func TestAutoExpand(t *testing.T) {
 	if s != "baz" {
 		t.Fatalf(`Expected "baz" but got %q`, s)
 	}
+}
+
+func TestSettingPwd(t *testing.T) {
+	pwd := "/"
+	out := &bytes.Buffer{}
+	ran, err := ExecAt(nil, out, nil, pwd, "pwd")
+	if err != nil {
+		t.Fatalf("unexpected error from runner: %#v", err)
+	}
+	if !ran {
+		t.Errorf("expected ran to be true but was false.")
+	}
+	if out.String() != fmt.Sprintf("%s\n", pwd) {
+		t.Errorf("expected %s, got %q", fmt.Sprintf("%s\n", pwd), out)
+	}
+}
 
+func TestSettingNoPwd(t *testing.T) {
+	currentWd, err := os.Getwd()
+	if err != nil {
+		t.Errorf("Failed getting current working directory")
+	}
+	out := &bytes.Buffer{}
+	ran, err := ExecAt(nil, out, nil, "", "pwd")
+	if err != nil {
+		t.Fatalf("unexpected error from runner: %#v", err)
+	}
+	if !ran {
+		t.Errorf("expected ran to be true but was false.")
+	}
+	if out.String() != fmt.Sprintf("%s\n", currentWd) {
+		t.Errorf("expected %s, got %q", fmt.Sprintf("%s\n", currentWd), out)
+	}
+}
+
+func TestSettingInvalidPwd(t *testing.T) {
+	pwd := "/i-am-expected-to-not-exist"
+	out := &bytes.Buffer{}
+	_, err := ExecAt(nil, out, nil, pwd, "pwd")
+	if err == nil {
+		t.Fatalf("I am expected to fail because path %s does not exist", pwd)
+	}
 }