Following changes:

 * Upgrade to Go 18 (along with use of generics)
 * OS version upgrades in Docker image and test cases
 * verbose option
 * increased test case coverage
 * POSIX-compliance in command-line option
 * show version
 * Check if file exists before moving
 * dynamic parallelism

Author: m-manu

.github/workflows/build-and-test.yml

@@ -5,14 +5,14 @@ on:
       - main
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
       - name: Setup Golang
         uses: actions/setup-go@v2
         with:
-          go-version: 1.17
+          go-version: 1.18
       - name: Build code
         run: go build
       - name: Test code

.gitignore

@@ -1,4 +1,6 @@
 /rsync-sidekick
 /.idea/
 *.sh
-*.txt
+*.txt
+*.out
+/test_cases_*

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.17-alpine3.14 as builder
+FROM golang:1.18-alpine3.15 as builder
 
 RUN apk --no-cache add build-base
 
@@ -12,9 +12,9 @@ COPY . .
 
 RUN go build
 
-RUN go test ./...
+RUN go test -v ./...
 
-FROM alpine:3.14
+FROM alpine:3.15
 
 RUN apk --no-cache add bash rsync
 

README.md

@@ -12,7 +12,7 @@ photos, etc.) _that are reorganized frequently_.
 
 `rsync-sidekick` is a safe and simple tool that is designed to run **before** `rsync` is run.
 
-This propagates following changes from _source directory_ to _destination directory_ (or any combination of below):
+This propagates following changes (or any combination) from _source directory_ to _destination directory_:
 
 1. Change in file modification timestamp
 2. Rename of file/directory
@@ -22,7 +22,7 @@ Note:
 
 * This tool **does not delete** any files or folders (under any circumstances) -- that's why safe-to-use 😌
     * Your files are just _moved around_
-    * Now, if you're uncomfortable with this tool even moving your files around, there is a `-shellscript` option, that
+    * Now, if you're uncomfortable with this tool even moving your files around, there is a `--shellscript` option, that
       just generates a script for you to read and run (think of it like a `--dry-run` option)
 * This tool **does not** actually **transfer** files -- that's for `rsync` to do 🙂
 * Since you'd run `rsync` after this tool is run, any changes that this tool couldn't propagate would just be propagated
@@ -32,8 +32,10 @@ Note:
 
 ## How to install?
 
-1. Install Go version at least **1.17**
-    * See: [Go installation instructions](https://go.dev/doc/install)
+1. Install Go version at least **1.18**
+    * On Ubuntu: `snap install go`
+    * On Mac: `brew install go`
+    * For anything else: [Go downloads page](https://go.dev/dl/)
 2. Run command:
    ```bash
    go install github.com/m-manu/rsync-sidekick@latest
@@ -45,40 +47,44 @@ Note:
 
 ## How to use?
 
-### Step 1
-
-Run this tool:
+**Step 1**: Run this tool
 
 ```bash
 rsync-sidekick /Users/manu/Photos/ /Volumes/Portable/Photos/
 ```
 
-### Step 2
-
-Run `rsync` as you would normally do:
+**Step 2**: Run `rsync` as you would normally do
 
 ```bash
-# (note the trailing slashes -- without them, rsync's behavior is different)
+# Note the trailing slashes below. Without them, rsync's behavior is different!
 rsync -av /Users/manu/Photos/ /Volumes/Portable/Photos/ 
 ```
 
 ## Command line options
 
-Running `rsync-sidekick -help` displays following information:
+Running `rsync-sidekick --help` displays following information:
 
 ```
-usage:
-	rsync-sidekick <flags> [source-dir] [destination-dir]
-where:
-	source-dir        Source directory
-	destination-dir   Destination directory
+rsync-sidekick is a tool to propagate file renames, movements and timestamp changes from a source directory to a destination directory.
+
+Usage:
+	 rsync-sidekick <flags> [source-dir] [destination-dir]
+
+where,
+	[source-dir]        Source directory
+	[destination-dir]   Destination directory
+
 flags: (all optional)
-  -exclusions string
-    	path to a text file that contains ignorable file/directory names separated by new lines (even without this flag, this tool ignores commonly ignorable names such as 'System Volume Information', 'Thumbs.db' etc.)
-  -extrainfo
-    	generate extra information (caution: makes it slow!)
-  -shellscript
-    	instead of applying changes directly, generate a shell script (this flag is useful if you want run the shell script as a different user)
+  -x, --exclusions string   path to file containing newline separated list of file/directory names to be excluded
+                            (even if this is not set, files/directories such these will still be ignored: $RECYCLE.BIN, desktop.ini, Thumbs.db etc.)
+  -h, --help                display help
+      --list                list files along their metadata for given directory
+  -s, --shellscript         instead of applying changes directly, generate a shell script
+                            (this flag is useful if you want 'dry run' this tool or want to run the shell script as a different user)
+  -v, --verbose             generates extra information, even a file dump (caution: makes it slow!)
+      --version             show version
+
+More details here: https://github.com/m-manu/rsync-sidekick
 ```
 
 ## Running this from a Docker container

action/action.go

@@ -16,6 +16,8 @@ type SyncAction interface {
 	Uniqueness() string
 }
 
+const cmdSeparator = "\u0001"
+
 func escape(path string) string {
 	escaped := path
 	escaped = strings.ReplaceAll(escaped, "\\", "\\\\") // This replace should be first

action/make_directory_action.go

@@ -30,7 +30,7 @@ func (a MakeDirectoryAction) Perform() error {
 
 // Uniqueness generates unique string for directory creation
 func (a MakeDirectoryAction) Uniqueness() string {
-	return "Mkdir\u0001" + a.AbsoluteDirPath
+	return "Mkdir" + cmdSeparator + a.AbsoluteDirPath
 }
 
 func (a MakeDirectoryAction) String() string {

action/move_file_action.go

@@ -1,6 +1,7 @@
 package action
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -23,17 +24,23 @@ func (a MoveFileAction) destinationPath() string {
 
 // UnixCommand for moving or renaming a file
 func (a MoveFileAction) UnixCommand() string {
-	return fmt.Sprintf(`mv -v "%s" "%s"`, escape(a.sourcePath()), escape(a.destinationPath()))
+	return fmt.Sprintf(`mv -v -n "%s" "%s"`, escape(a.sourcePath()), escape(a.destinationPath()))
 }
 
 // Perform 'file move/rename' action
 func (a MoveFileAction) Perform() error {
-	return os.Rename(a.sourcePath(), a.destinationPath())
+	if _, err := os.Stat(a.destinationPath()); err == nil {
+		return fmt.Errorf(`error: file "%s" already exists`, a.destinationPath())
+	} else if errors.Is(err, os.ErrNotExist) {
+		return os.Rename(a.sourcePath(), a.destinationPath())
+	} else {
+		return err
+	}
 }
 
 // Uniqueness generates unique string for file renaming/movement
 func (a MoveFileAction) Uniqueness() string {
-	return "mv\u0001" + a.RelativeFromPath
+	return "mv" + cmdSeparator + a.RelativeFromPath
 }
 
 func (a MoveFileAction) String() string {

action/propagate_timestamp_action.go

@@ -39,7 +39,7 @@ func (a PropagateTimestampAction) Perform() error {
 
 // Uniqueness generate unique string for 'file modification timestamp' propagation action
 func (a PropagateTimestampAction) Uniqueness() string {
-	return "touch\u0001" + a.DestinationFileRelativePath
+	return "touch" + cmdSeparator + a.DestinationFileRelativePath
 }
 
 func (a PropagateTimestampAction) String() string {