How to Create a Copy of a Directory in Unix/Linux

Copying directories is a fundamental operation in Unix and Linux systems. Whether you're backing up files, duplicating project structures, or moving data between locations, understanding the different methods and their appropriate use cases will make your file management tasks more efficient.

Prerequisites

You'll need access to a Unix or Linux terminal with basic command-line knowledge. The commands shown work on most Unix-like systems including Linux, macOS, and BSD variants.

Method 1: Using cp Command (Basic Copy)

The cp command is the most straightforward way to copy directories. Use the -r (recursive) flag to copy directories and their contents:

cp -r source_directory destination_directory

For example, to copy a directory called projects to projects_backup:

cp -r projects projects_backup

If the destination directory doesn't exist, it will be created. If it exists, the source directory will be copied inside it.

Method 2: Using cp with Preservation Options

To preserve file attributes like timestamps, permissions, and ownership during copying:

cp -rp source_directory destination_directory

The -p flag preserves:

• File timestamps (modification, access times)
• File permissions
• File ownership (when possible)

For maximum preservation, use the -a (archive) flag:

cp -a source_directory destination_directory

The -a flag is equivalent to -dpR and preserves everything possible including symbolic links.

Method 3: Using rsync for Advanced Copying

The rsync command offers more control and efficiency, especially for large directories:

rsync -av source_directory/ destination_directory/

Key advantages of rsync:

• Only copies changed files (incremental copying)
• Shows progress during transfer
• Better handling of symbolic links and special files

Common rsync options:

• -a: Archive mode (preserves permissions, timestamps, etc.)
• -v: Verbose output
• -z: Compress data during transfer
• --progress: Show transfer progress

Example with progress display:

rsync -av --progress source_directory/ destination_directory/

Method 4: Using tar for Exact Replication

The tar command can create exact copies while preserving all file attributes:

tar -cf - source_directory | tar -xf - -C destination_path

This method pipes the tar archive directly to extract, creating an exact copy. To copy myproject to /backup/myproject:

tar -cf - myproject | tar -xf - -C /backup/

Copying Directory Contents Only

To copy only the contents of a directory (not the directory itself), add a trailing slash to the source:

cp -r source_directory/* destination_directory/

Or with rsync:

rsync -av source_directory/ destination_directory/

Note the difference:

• source_directory copies the directory itself
• source_directory/ copies the contents only

Handling Special Cases

Copying Hidden Files: The cp command with * won't copy hidden files. Use:

cp -r source_directory/. destination_directory/

Excluding Specific Files: With rsync, you can exclude patterns:

rsync -av --exclude='*.log' --exclude='node_modules/' source/ dest/

Following Symbolic Links: To copy the actual files that symbolic links point to:

cp -rL source_directory destination_directory

Interactive and Safe Copying

To prompt before overwriting existing files:

cp -ri source_directory destination_directory

To prevent accidental overwrites (no-clobber):

cp -rn source_directory destination_directory

Copying Across File Systems

When copying between different file systems or when you want to ensure all attributes are preserved:

rsync -avX source_directory/ destination_directory/

The -X flag preserves extended attributes on supported file systems.

Creating Backups with Timestamps

To create backups with timestamps in the directory name:

backup_name="backup_$(date +%Y%m%d_%H%M%S)"
cp -a important_directory "$backup_name"

This creates directories like backup_20241212_143052.

Monitoring Copy Progress

For large directories, monitor progress with pv (pipe viewer):

tar -cf - source_directory | pv | tar -xf - -C destination_path

Or use rsync's built-in progress:

rsync -av --progress --stats source_directory/ destination_directory/

Performance Considerations

For Local Copies: cp is usually fastest for simple operations:

cp -a source dest

For Large Directories: rsync is more efficient for subsequent copies:

rsync -av source/ dest/

For Remote Copies: rsync over SSH:

rsync -av source_directory/ user@remote:/path/destination/

Common Gotchas and Solutions

Problem: Copying fails due to permissions
Solution: Use sudo when necessary:

sudo cp -a source_directory destination_directory

Problem: Running out of space during copy
Solution: Check available space first:

df -h destination_path
du -sh source_directory

Problem: Interrupting a copy operation
Solution: Use rsync for resumable transfers:

rsync -av --partial source_directory/ destination_directory/

Scripting Directory Copies

Create a reusable backup script:

#!/bin/bash
backup_directory() {
    local source="$1"
    local backup_base="$2"
    local timestamp=$(date +%Y%m%d_%H%M%S)
    local backup_dir="${backup_base}/backup_${timestamp}"

    echo "Creating backup: $backup_dir"
    rsync -av "$source/" "$backup_dir/"
    echo "Backup completed successfully"
}

# Usage: backup_directory /home/user/documents /backups

Next Steps

Now that you can copy directories effectively, consider learning about:

• Setting up automated backups with cron jobs
• Using find command for selective copying
• Implementing incremental backup strategies
• Working with compression tools like gzip and xz
• Managing file permissions and ownership