Support multiple file/directory arguments for all commands

- Change sum add, sum update, check, and clear to accept 1+ paths
- Update README usage examples to show multiple path support
- Add TODO section with planned future improvements

README.md

@@ -31,20 +31,20 @@ Semantic Versioning 2.0.0 is used for tags.
 ## Usage
 
 ```bash
-# add checksum & timestamp xattrs to every regular file under DIR
-attrsum sum add DIR
+# add checksum & timestamp xattrs to every regular file under one or more paths
+attrsum sum add DIR1 DIR2 file.txt
 
 # update checksum only when file mtime is newer than stored sumtime
-attrsum sum update DIR
+attrsum sum update DIR1 DIR2
 
 # verify checksums, stop on first error
-attrsum check DIR
+attrsum check DIR1 DIR2
 
 # verify every file, reporting each result, keep going after errors
-attrsum -v check --continue DIR
+attrsum -v check --continue DIR1 DIR2
 
 # remove checksum & timestamp xattrs
-attrsum clear DIR
+attrsum clear DIR1 DIR2
 ```
 
 | xattr key                                   | meaning                        |
@@ -71,6 +71,21 @@ required.  Now you can trust a USB stick didn't eat your data.
 
 ---
 
+## TODO
+
+Future improvements under consideration:
+
+- **Quiet mode (`-q`)** — suppress all output except errors
+- **Dry-run mode (`--dry-run`, `-n`)** — show what would be done without making changes
+- **JSON output (`--json`)** — machine-readable output for scripting and integration
+- **Parallel processing (`-j N`)** — use multiple goroutines for faster checksumming on large trees
+- **Progress indicator** — show progress bar or spinner for long-running operations
+- **Summary report** — print statistics on completion (files processed, errors, bytes hashed)
+- **Read paths from stdin (`-`)** — support piping file lists, e.g. `find ... | attrsum sum add -`
+- **Exit code documentation** — formalize and document exit codes for scripting
+
+---
+
 ## Contributing
 
 * Author & maintainer: **sneak** – <sneak@sneak.berlin>

attrsum.go

@@ -62,17 +62,31 @@ func newSumCmd() *cobra.Command {
     }
 
     add := &cobra.Command{
-        Use:   "add <dir>",
+        Use:   "add <path>...",
         Short: "Write checksums for files missing them",
-        Args:  cobra.ExactArgs(1),
-        RunE: func(_ *cobra.Command, a []string) error { return ProcessSumAdd(a[0]) },
+        Args:  cobra.MinimumNArgs(1),
+        RunE: func(_ *cobra.Command, a []string) error {
+            for _, p := range a {
+                if err := ProcessSumAdd(p); err != nil {
+                    return err
+                }
+            }
+            return nil
+        },
     }
 
     upd := &cobra.Command{
-        Use:   "update <dir>",
+        Use:   "update <path>...",
         Short: "Recalculate checksum when file newer than stored sumtime",
-        Args:  cobra.ExactArgs(1),
-        RunE: func(_ *cobra.Command, a []string) error { return ProcessSumUpdate(a[0]) },
+        Args:  cobra.MinimumNArgs(1),
+        RunE: func(_ *cobra.Command, a []string) error {
+            for _, p := range a {
+                if err := ProcessSumUpdate(p); err != nil {
+                    return err
+                }
+            }
+            return nil
+        },
     }
 
     cmd.AddCommand(add, upd)
@@ -129,10 +143,17 @@ func readSumTime(path string) (time.Time, error) {
 
 func newClearCmd() *cobra.Command {
     return &cobra.Command{
-        Use:   "clear <dir>",
+        Use:   "clear <path>...",
         Short: "Remove checksum xattrs from tree",
-        Args:  cobra.ExactArgs(1),
-        RunE: func(_ *cobra.Command, a []string) error { return ProcessClear(a[0]) },
+        Args:  cobra.MinimumNArgs(1),
+        RunE: func(_ *cobra.Command, a []string) error {
+            for _, p := range a {
+                if err := ProcessClear(p); err != nil {
+                    return err
+                }
+            }
+            return nil
+        },
     }
 }
 
@@ -164,10 +185,17 @@ func ProcessClear(dir string) error {
 func newCheckCmd() *cobra.Command {
     var cont bool
     cmd := &cobra.Command{
-        Use:   "check <dir>",
+        Use:   "check <path>...",
         Short: "Verify stored checksums",
-        Args:  cobra.ExactArgs(1),
-        RunE: func(_ *cobra.Command, a []string) error { return ProcessCheck(a[0], cont) },
+        Args:  cobra.MinimumNArgs(1),
+        RunE: func(_ *cobra.Command, a []string) error {
+            for _, p := range a {
+                if err := ProcessCheck(p, cont); err != nil {
+                    return err
+                }
+            }
+            return nil
+        },
     }
     cmd.Flags().BoolVar(&cont, "continue", false, "continue after errors and report each file")
     return cmd