feat: add command output/error option

cli/run.go

@@ -24,7 +24,7 @@ type Closer interface {
 }
 
 func Run(ctx context.Context, root *cmds.Command,
-	cmdline []string, stdin, stdout, stderr *os.File,
+	cmdline []string, stdin, stderr *os.File,
 	buildEnv cmds.MakeEnvironment, makeExecutor cmds.MakeExecutor) error {
 
 	printErr := func(err error) {
@@ -33,6 +33,21 @@ func Run(ctx context.Context, root *cmds.Command,
 
 	req, errParse := Parse(ctx, cmdline[1:], stdin, root)
 
+	var out *os.File
+	if outFile, _ := req.Options[cmds.OutputFile].(string); outFile != "" {
+		// FIXME: Consider exporting the extract file logic (used in `ipfs get`)
+		//  and using it here (https://github.com/ipfs/tar-utils/blob/16821db/extractor.go#L277).
+		var err error
+		out, err = os.Create(outFile)
+		if err != nil {
+			printErr(err)
+			return err
+		}
+		// FIXME(BLOCKING): Where do we close the file? When the resp emitter closes?
+	} else {
+		out = os.Stdout
+	}
+
 	// Handle the timeout up front.
 	var cancel func()
 	if timeoutStr, ok := req.Options[cmds.TimeoutOpt]; ok {
@@ -72,7 +87,7 @@ func Run(ctx context.Context, root *cmds.Command,
 
 	// BEFORE handling the parse error, if we have enough information
 	// AND the user requested help, print it out and exit
-	err := HandleHelp(cmdline[0], req, stdout)
+	err := HandleHelp(cmdline[0], req, out)
 	if err == nil {
 		return nil
 	} else if err != ErrNoHelpRequested {
@@ -98,7 +113,7 @@ func Run(ctx context.Context, root *cmds.Command,
 	// - commands with no Run func are invoked directly.
 	// - the main command is invoked.
 	if req == nil || req.Command == nil || req.Command.Run == nil {
-		printHelp(false, stdout)
+		printHelp(false, out)
 		return nil
 	}
 
@@ -127,7 +142,7 @@ func Run(ctx context.Context, root *cmds.Command,
 		req.Options[cmds.EncLong] = cmds.JSON
 	}
 
-	re, err := NewResponseEmitter(stdout, stderr, req)
+	re, err := NewResponseEmitter(out, stderr, req)
 	if err != nil {
 		printErr(err)
 		return err

cli/run_test.go

@@ -41,7 +41,8 @@ func TestRunWaits(t *testing.T) {
 		context.Background(),
 		root,
 		[]string{"test", "test"},
-		devnull, devnull, devnull,
+		// FIXME(BLOCKING): Redirect to devnull instead of stdout.
+		devnull, devnull,
 		func(ctx context.Context, req *cmds.Request) (cmds.Environment, error) {
 			return env{flag}, nil
 		},

executor.go

@@ -28,6 +28,8 @@ func NewExecutor(root *Command) Executor {
 	}
 }
 
+// This is the *CLI* Executor (though is not in that package). The other one is
+// the `client` HTTP Executor (defined in the HTTP package).
 type executor struct {
 	root *Command
 }

opts.go

@@ -12,10 +12,13 @@ const (
 	OptLongHelp  = "help"
 	DerefLong    = "dereference-args"
 	StdinName    = "stdin-name"
-	Hidden       = "hidden"
-	HiddenShort  = "H"
-	Ignore       = "ignore"
-	IgnoreRules  = "ignore-rules-path"
+	// FIXME(BLOCKING): Review names. (We may be able to use "output" once
+	//  it's cleaned from subcommands.)
+	OutputFile  = "command-output"
+	Hidden      = "hidden"
+	HiddenShort = "H"
+	Ignore      = "ignore"
+	IgnoreRules = "ignore-rules-path"
 )
 
 // options that are used by this package
@@ -25,6 +28,7 @@ var OptionStreamChannels = BoolOption(ChanOpt, "Stream channel output")
 var OptionTimeout = StringOption(TimeoutOpt, "Set a global timeout on the command")
 var OptionDerefArgs = BoolOption(DerefLong, "Symlinks supplied in arguments are dereferenced")
 var OptionStdinName = StringOption(StdinName, "Assign a name if the file source is stdin.")
+var OptionOutputFile = StringOption(OutputFile, "Filename to save the output in (by default it's redirected to stdout).")
 var OptionHidden = BoolOption(Hidden, HiddenShort, "Include files that are hidden. Only takes effect on recursive add.")
 var OptionIgnore = StringsOption(Ignore, "A rule (.gitignore-stype) defining which file(s) should be ignored (variadic, experimental)")
 var OptionIgnoreRules = StringOption(IgnoreRules, "A path to a file with .gitignore-style ignore rules (experimental)")