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https://github.com/agarwalvishal/verifycopy

A lightweight shell script to verify successful file and folder copies by comparing path, size, and optional timestamps.
https://github.com/agarwalvishal/verifycopy

backup copy-validation file-check macos shell utility verification zsh

Last synced: about 2 months ago
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A lightweight shell script to verify successful file and folder copies by comparing path, size, and optional timestamps.

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README 

          
# verifycopy.zsh



A clean, reliable shell script to verify whether files and folders were completely and correctly copied from a source to a destination directory — including subdirectories and hidden files.



Designed for **post-copy sanity checking**: useful after backups, manual drag-and-drop transfers, SD card dumps, or Android file transfers.



---



## What This Script Does



- Recursively compares all files (including hidden ones) between source and destination

- Compares:

  - Relative file paths

  - File sizes (in bytes)

  - (Optionally) file modification timestamps

- Detects:

  - Files missing in the destination

  - Extra files in the destination

  - Files with same path but different size or timestamp (marked as changed)

- Skips:

  - macOS AppleDouble files (`._*`) that contain metadata but not actual file content

  - `.DS_Store` files — macOS Finder metadata that clutters directories but has no user data

- Outputs:

  - A **color-coded summary** in terminal

  - A detailed **diff-style log** saved as `verifycopy_diff_output.txt` in the script directory



---



## Why AppleDouble Files (`._*`) Are Excluded



When copying to non-macOS file systems (e.g. FAT32, exFAT, NTFS, SMB), macOS generates `._*` files — known as **AppleDouble files** — to store extended metadata like:



- Finder tags and labels

- Custom icons

- Resource forks



These files are not user content, are invisible on macOS, and often confuse verification.  

This script **excludes them by default**, ensuring they don't pollute the results.  

Normal dotfiles (like `.bashrc`, `.config`) are **not affected** and are fully included.



---



## Why Timestamp Checking Matters



Timestamps detect changes that file size cannot — for example:



- File was edited but size didn't change

  - In real-world edits, file size can remain the same (e.g., a text file is edited but eventually it contains the same number of characters and therefore has the same size), but timestamp can change — enabling timestamp check helps detect such changes reliably without needing checksums.

- File was re-encoded or touched

- File was modified during sync



**Timestamp comparison is optional** because some copy methods don’t preserve timestamps.



### When to Enable Timestamp Checks



> Enable when:

>

> - You used reliable methods that preserve timestamps

> - You want to ensure copied files weren’t modified after transfer



### When to Disable Timestamp Checks



> Disable when:

>

> - You copied via MTP, browser, or plain `cp`

> - You want to avoid false positives due to timestamp differences



**Recommendation:** Enable timestamp checks unless you know your copy tool strips them



---



## Reference: Copy Methods and Timestamps



### Copy Methods That Preserve Timestamps



| Method                     | Preserves Timestamps |

|----------------------------|----------------------|

| `rsync -a`, `rsync -av`    | ✅ Yes               |

| `cp -p`, `cp -a`           | ✅ Yes               |

| macOS Finder (drag & drop) | ✅ Yes               |



### Copy Methods That Strip Timestamps



| Method / Tool                 | Preserves Timestamps |

|-------------------------------|----------------------|

| `cp` (without `-p`)           | ❌ No                |

| Web/browser downloads         | ❌ No                |

| Android MTP transfer          | ❌ No                |

| Some network (SMB/NFS) shares | ❌ No                |



---



## What This Script Does Not Do



While `verifycopy.zsh` is ideal for most real-world usage, it does **not** perform full content-level validation. Specifically:



- It does **not** compare actual file contents (no hashing or checksums)

- It does **not** verify file permissions, symlinks, or extended attributes

- It does **not** detect bit-level corruption when size and timestamp are identical



If you need full integrity verification, use `rsync` with checksums (see next section).



---



## Why Not Just Use rsync?



While `rsync` is a powerful tool that can detect missing or changed files — and even verify content with checksums — this script exists because:



| Feature / Need                            | `verifycopy.zsh` ✅ | `rsync` (with `--dry-run`) |

|-------------------------------------------|----------------------|-----------------------------|

| Designed purely for **post-copy verification** | ✅ Yes              | ❌ No (sync-focused)        |

| Fully **read-only**, always safe          | ✅ Yes              | ⚠️ Only with `--dry-run`    |

| Clear, **human-readable summary**         | ✅ Yes              | ❌ No (cryptic output)      |

| Detects **extras in destination**         | ✅ Yes              | ❌ No (requires complex setup) |

| Color-coded terminal output               | ✅ Yes              | ❌ No                       |

| Logs to diff-style file                   | ✅ Yes              | ❌ No                       |

| Skips macOS `._*` clutter automatically   | ✅ Yes              | ⚠️ Only with `--exclude='._*'` |

| Supports **timestamp optionality**        | ✅ Yes              | ✅ Yes (`--size-only`)      |

| Supports **checksum-based comparison**    | ❌ No               | ✅ Yes (`-c`)               |



If you need full bit-level verification (e.g. for archives or production systems), use:



```bash

rsync -avc --dry-run --exclude='._*' /source/ /destination/

```



But for day-to-day safety checks after copying files, `verifycopy.zsh` is faster, simpler, and safer to use.



---



## Installation



### Clone the Script



```bash

git clone https://github.com/agarwalvishal/verifycopy.git ~/Tools/verifycopy

cd ~/Tools/verifycopy

chmod +x verifycopy.zsh

```



### Create a Symlink to Run It Anywhere



```bash

ln -s ~/Tools/verifycopy/verifycopy.zsh /usr/local/bin/verifycopy

```



You can now run:



```bash

verifycopy

```



---



## Usage



Run the script:



```bash

verifycopy

```



Then:



- Enter the source folder path

- Enter the destination folder path

- Choose whether to compare timestamps



After scanning and comparing, a diff log is saved as:



```bash

~/Tools/verifycopy/verifycopy_diff_output.txt

```



---



## Uninstalling



To remove the command:



```bash

rm /usr/local/bin/verifycopy

```



To delete the script and diff output:



```bash

rm -rf ~/Tools/verifycopy

```



---



## Summary



`verifycopy.zsh` is a focused tool that answers a simple but critical question:



> "Did all my files copy correctly?"



- It verifies the success of manual file copies and provides peace of mind before deleting original files and helps catch skips, overwrites, or modifications.

- It’s designed to give you fast, trustworthy feedback — without needing to understand `rsync`, parse obscure flags, or risk overwriting data.

- Use it confidently for backups, file migrations, or post-transfer validation when bit-level hashing is overkill.



---



## Test Coverage



This script is backed by an automated test suite covering all meaningful file copy edge cases — including missing files, size mismatches, timestamp-only differences, and known safe exclusions.



👉 [View the full test coverage matrix here](./TEST_COVERAGE.md)