Implement the rclone cat command

cmd/all/all.go

@@ -5,6 +5,7 @@ import (
 	// Active commands
 	_ "github.com/ncw/rclone/cmd"
 	_ "github.com/ncw/rclone/cmd/authorize"
+	_ "github.com/ncw/rclone/cmd/cat"
 	_ "github.com/ncw/rclone/cmd/check"
 	_ "github.com/ncw/rclone/cmd/cleanup"
 	_ "github.com/ncw/rclone/cmd/config"

cmd/cat/cat.go

@@ -0,0 +1,40 @@
+package cat
+
+import (
+	"os"
+
+	"github.com/ncw/rclone/cmd"
+	"github.com/ncw/rclone/fs"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	cmd.Root.AddCommand(catCmd)
+}
+
+var catCmd = &cobra.Command{
+	Use:   "cat remote:path",
+	Short: `Concatenates any files and sends them to stdout.`,
+	Long: `
+rclone cat sends any files to standard output.
+
+You can use it like this to output a single file
+
+    rclone cat remote:path/to/file
+
+Or like this to output any file in dir or subdirectories.
+
+    rclone cat remote:path/to/dir
+
+Or like this to output any .txt files in dir or subdirectories.
+
+    rclone --include "*.txt" cat remote:path/to/dir
+`,
+	Run: func(command *cobra.Command, args []string) {
+		cmd.CheckArgs(1, 1, command, args)
+		fsrc := cmd.NewFsSrc(args)
+		cmd.Run(false, command, func() error {
+			return fs.Cat(fsrc, os.Stdout)
+		})
+	},
+}

fs/operations.go

@@ -1012,3 +1012,34 @@ func CleanUp(f Fs) error {
 	}
 	return fc.CleanUp()
 }
+
+// Cat any files to the io.Writer
+func Cat(f Fs, w io.Writer) error {
+	var mu sync.Mutex
+	return ListFn(f, func(o Object) {
+		Stats.Transferring(o.Remote())
+		defer Stats.DoneTransferring(o.Remote())
+		mu.Lock()
+		defer mu.Unlock()
+		in, err := o.Open()
+		if err != nil {
+			Stats.Error()
+			ErrorLog(o, "Failed to open: %v", err)
+			return
+		}
+		defer func() {
+			err = in.Close()
+			if err != nil {
+				Stats.Error()
+				ErrorLog(o, "Failed to close: %v", err)
+			}
+		}()
+		inAccounted := NewAccount(in, o) // account the transfer
+		_, err = io.Copy(w, inAccounted)
+		if err != nil {
+			Stats.Error()
+			ErrorLog(o, "Failed to send to output: %v", err)
+		}
+	})
+
+}

fs/operations_test.go

@@ -620,3 +620,21 @@ func TestDeduplicateRename(t *testing.T) {
 		}
 	}
 }
+
+func TestCat(t *testing.T) {
+	r := NewRun(t)
+	defer r.Finalise()
+	file1 := r.WriteBoth("file1", "aaa", t1)
+	file2 := r.WriteBoth("file2", "bbb", t2)
+
+	fstest.CheckItems(t, r.fremote, file1, file2)
+
+	var buf bytes.Buffer
+	err := fs.Cat(r.fremote, &buf)
+	require.NoError(t, err)
+	res := buf.String()
+
+	if res != "aaabbb" && res != "bbbaaa" {
+		t.Errorf("Incorrect output from Cat: %q", res)
+	}
+}