Rsync Skipping Non-Regular Files: Understanding and Resolving the Error

The error message “rsync prints skipping non-regular file for what appears to be a regular directory” typically occurs during file synchronization processes using the rsync command. This issue arises when rsync encounters files that are not regular files, such as symbolic links or special device files, and skips them. This can be significant in backup and mirroring operations, as it may lead to incomplete data transfers if important files are skipped. Understanding and addressing this error ensures reliable and accurate file synchronization.

: Bobcares

Understanding the Error Message

When rsync prints “skipping non-regular file for what appears to be a regular directory,” it means that rsync encountered a file that it doesn’t recognize as a regular file or directory. This often happens with special file types like symbolic links, device files, or sockets.

Technical Aspects of rsync

File Types Identification

rsync uses the stat system call to identify file types. Here are the primary file types it handles:

1. Regular Files: These are standard files containing data. rsync copies these files directly.
2. Directories: These are containers for other files and directories. rsync traverses directories recursively if the -r or -a (archive) option is used.
3. Symbolic Links: These are pointers to other files or directories. By default, rsync skips these unless the -l option is specified to copy symlinks as symlinks.
4. Special Files: These include device files, sockets, and named pipes. rsync typically skips these unless specific options are used.

Handling Different File Types

• Regular Files: rsync copies these files byte-by-byte.
• Directories: With the -r or -a option, rsync enters directories and processes their contents.
• Symbolic Links: By default, rsync skips symlinks. Using the -l option, rsync copies the symlink itself, not the file it points to.
• Special Files: These are skipped unless options like --devices or --specials are used.

Example Scenario

If you run rsync -av /source/ /destination/ and encounter a symbolic link in /source/, rsync will print “skipping non-regular file” unless you include the -l option.

Common Solutions

• Include Symlinks: Use -l to copy symlinks as symlinks.
• Recursive Mode: Ensure -r or -a is used to handle directories properly.
• Special Files: Use --devices or --specials if you need to copy device files or other special file types.

This behavior ensures that rsync only processes files it can handle correctly, avoiding potential issues with unsupported file types.

Common Causes

Here are common causes for the “rsync prints skipping non-regular file for what appears to be a regular directory” error:

1. Symbolic Links:

   • Cause: By default, rsync skips symbolic links.
   • Solution: Use the --links or -l option to copy symlinks as symlinks. Alternatively, use --copy-links to copy the files they point to.

2. Special Files:

   • Cause: Rsync skips special files like device files, sockets, and FIFOs by default.
   • Solution: Use the --devices and --specials options to include these files in the transfer.

3. Incorrect Rsync Options:

   • Cause: Missing recursive mode options.
   • Solution: Use -r for recursive copying or -a for archive mode, which includes recursive copying and preserves permissions, timestamps, and other attributes.

4. Missing Permissions:

   • Cause: Lack of necessary permissions to read or write files.
   • Solution: Ensure that the user running rsync has the appropriate permissions on both the source and destination directories.

5. File System Incompatibilities:

   • Cause: Differences in file system capabilities between source and destination.
   • Solution: Ensure both file systems support the same types of files and attributes.

6. Use of --info=nonreg0:

   • Cause: To suppress non-regular file messages.
   • Solution: Use the --info=nonreg0 option to silence these messages.

: Bobcares
: GitHub

Troubleshooting Steps

Here’s a step-by-step guide to troubleshoot and resolve the “rsync prints skipping non-regular file for what appears to be a regular directory” error:

1. Identify Symbolic Links:

   • Use the file command to check if the files are symbolic links.

     file /path/to/file
     

   • Alternatively, use find to locate all symbolic links in a directory.

     find /path -type l
     

2. Copy Symbolic Links as Links:

   • Add the -l option to your rsync command to copy symbolic links as links.

     rsync -rtvpl /source/backup /destination
     

3. Copy the Files Referenced by Symbolic Links:

   • Use the -L option to copy the files that the symbolic links point to.

     rsync -rtvpL /source/backup /destination
     

4. Enable Recursive Mode:

   • Ensure you are using the -r or -a option to enable recursive mode.

     rsync -rPz /my/local/back/ destination:/my/remote/dir
     

   • The -a option is recommended as it preserves file hierarchies, including special files and permissions.

     rsync -av /source/backup /destination
     

5. Suppress Non-Regular File Warnings:

   • If you want to suppress the “skipping non-regular file” messages, use the --info=nonreg0 option.

     rsync --info=nonreg0 -rtvp /source/backup /destination
     

6. Verify and Retry:

   • After making the necessary adjustments, run the rsync command again to verify if the issue is resolved.

These steps should help you identify and fix the issue with rsync.

Preventive Measures

To avoid the “rsync prints skipping non-regular file for what appears to be a regular directory” error and ensure effective use of rsync, follow these preventive measures and best practices:

Preventive Measures:

1. Check File Types: Ensure all files and directories are regular files before synchronization. Use find or file commands to verify.
2. Use Correct Options: Use -a (archive mode) to preserve file attributes and ensure proper handling of directories.
3. Exclude Non-Regular Files: Use the --exclude option to skip non-regular files (e.g., sockets, pipes).
4. Trailing Slash: Be mindful of trailing slashes in source paths. A trailing slash means “contents of this directory,” while no trailing slash means “this directory.”

Best Practices:

1. Dry Run: Use -n to perform a dry run and see what will be transferred without making any changes.
2. Verbose Output: Use -v for verbose output to get detailed information about the transfer process.
3. Progress Indicator: Use --progress to monitor the progress of the transfer.
4. Compression: Use -z to compress data during transfer, saving bandwidth.
5. SSH for Remote Transfers: Use -e ssh to ensure secure data transfer over SSH.
6. Backup Option: Use -b to create backups of files that are being updated or deleted.
7. Delete Option: Use --delete to remove files from the destination that no longer exist in the source, keeping both directories in sync.

By following these measures and best practices, you can effectively use rsync and avoid common errors.

To Address the ‘rsync Prints Skipping Non-Regular File’ Error

To address the “rsync prints skipping non-regular file for what appears to be a regular directory” error, it’s essential to understand its causes and take preventive measures. This issue often arises when rsync encounters directories that are not regular files, leading to skipped transfers and incomplete synchronization.

Key Points to Consider

• Ensure all files and directories are regular files before synchronization using `find` or `file` commands.
• Use the `-a` (archive mode) option to preserve file attributes and handle directories properly.
• Exclude non-regular files using the `–exclude` option, such as sockets and pipes.
• Be mindful of trailing slashes in source paths, as they can affect transfer behavior.

Best Practices for Efficient Rsync Usage

• Performing a dry run with `-n` to see what will be transferred without making changes.
• Using verbose output with `-v` for detailed information about the transfer process.
• Monitoring progress with `–progress`.
• Compressing data during transfer using `-z` to save bandwidth.
• Ensuring secure data transfer over SSH with `-e ssh`.
• Creating backups of updated or deleted files with `-b`.
• Removing files from the destination that no longer exist in the source with `–delete`.

By understanding and addressing this error, you can ensure efficient file synchronization using rsync.