Allow --files-from multiple times

Fixes https://github.com/restic/restic/issues/2085

changelog/unreleased/pull-2086

@@ -0,0 +1,10 @@
+Enhancement: Allow --files-from to be specified multiple times
+
+This change should help with managing backup sources as source paths
+can be specified in multiple files.
+Usage:
+
+restic backup --files-from afile --files-from anotherfile ..
+
+https://github.com/restic/restic/pull/2086
+https://github.com/restic/restic/issues/2085

cmd/restic/cmd_backup.go

@@ -45,9 +45,13 @@ given as the arguments.
 	},
 	DisableAutoGenTag: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		if backupOptions.Stdin && backupOptions.FilesFrom == "-" {
+		if backupOptions.Stdin {
+			for _, filename := range backupOptions.FilesFrom {
+				if filename == "-" {
 					return errors.Fatal("cannot use both `--stdin` and `--files-from -`")
 				}
+			}
+		}
 
 		var t tomb.Tomb
 		term := termstatus.New(globalOptions.stdout, globalOptions.stderr, globalOptions.Quiet)
@@ -75,7 +79,7 @@ type BackupOptions struct {
 	StdinFilename    string
 	Tags             []string
 	Host             string
-	FilesFrom        string
+	FilesFrom        []string
 	TimeStamp        string
 	WithAtime        bool
 }
@@ -101,7 +105,7 @@ func init() {
 	f.StringVar(&backupOptions.Host, "hostname", "", "set the `hostname` for the snapshot manually")
 	f.MarkDeprecated("hostname", "use --host")
 
-	f.StringVar(&backupOptions.FilesFrom, "files-from", "", "read the files to backup from file (can be combined with file args)")
+	f.StringArrayVar(&backupOptions.FilesFrom, "files-from", nil, "read the files to backup from file (can be combined with file args/can be specified multiple times)")
 	f.StringVar(&backupOptions.TimeStamp, "time", "", "time of the backup (ex. '2012-11-01 22:08:41') (default: now)")
 	f.BoolVar(&backupOptions.WithAtime, "with-atime", false, "store the atime for all files and directories")
 }
@@ -175,12 +179,16 @@ func readLinesFromFile(filename string) ([]string, error) {
 
 // Check returns an error when an invalid combination of options was set.
 func (opts BackupOptions) Check(gopts GlobalOptions, args []string) error {
-	if opts.FilesFrom == "-" && gopts.password == "" {
+	if gopts.password == "" {
+		for _, filename := range opts.FilesFrom {
+			if filename == "-" {
 				return errors.Fatal("unable to read password from stdin when data is to be read from stdin, use --password-file or $RESTIC_PASSWORD")
 			}
+		}
+	}
 
 	if opts.Stdin {
-		if opts.FilesFrom != "" {
+		if len(opts.FilesFrom) > 0 {
 			return errors.Fatal("--stdin and --files-from cannot be used together")
 		}
 
@@ -302,13 +310,14 @@ func collectTargets(opts BackupOptions, args []string) (targets []string, err er
 		return nil, nil
 	}
 
-	fromfile, err := readLinesFromFile(opts.FilesFrom)
+	var lines []string
+	for _, file := range opts.FilesFrom {
+		fromfile, err := readLinesFromFile(file)
 		if err != nil {
 			return nil, err
 		}
 
 		// expand wildcards
-	var lines []string
 		for _, line := range fromfile {
 			var expanded []string
 			expanded, err := filepath.Glob(line)
@@ -320,6 +329,7 @@ func collectTargets(opts BackupOptions, args []string) (targets []string, err er
 			}
 			lines = append(lines, expanded...)
 		}
+	}
 
 	// merge files from files-from into normal args so we can reuse the normal
 	// args checks and have the ability to use both files-from and args at the

doc/040_backup.rst

@@ -205,8 +205,8 @@ backup ``/sys`` or ``/dev`` on a Linux system:
     $ restic -r /srv/restic-repo backup --one-file-system /
 
 By using the ``--files-from`` option you can read the files you want to
-backup from a file. This is especially useful if a lot of files have to
-be backed up that are not in the same folder or are maybe pre-filtered
+backup from one or more files. This is especially useful if a lot of files have
+to be backed up that are not in the same folder or are maybe pre-filtered
 by other software.
 
 For example maybe you want to backup files which have a name that matches a

doc/manual_rest.rst

@@ -80,7 +80,7 @@ command:
           --exclude-caches                   excludes cache directories that are marked with a CACHEDIR.TAG file
           --exclude-file file                read exclude patterns from a file (can be specified multiple times)
           --exclude-if-present stringArray   takes filename[:header], exclude contents of directories containing filename (except filename itself) if header of that file is as provided (can be specified multiple times)
-          --files-from string                read the files to backup from file (can be combined with file args)
+          --files-from string                read the files to backup from file (can be combined with file args/can be specified multiple times)
       -f, --force                            force re-reading the target files/directories (overrides the "parent" flag)
       -h, --help                             help for backup
           --hostname hostname                set the hostname for the snapshot manually. To prevent an expensive rescan use the "parent" flag