virt-copy-out

virt-copy-out

virt-copy-out is a tool provided by libvirt that allows you to copy files or directories from a virtual machine (VM) disk image to the local filesystem of the host system. This is particularly useful for extracting files from virtual machines, especially when the VM is not running or when you need to recover files from a disk image.

Key Features of virt-copy-out

• Extract Files: Copy files or directories from the VM's disk image to a local directory on the host system.

• Non-Running VMs: Can be used to access files from a virtual machine's disk image even if the VM is not currently running.

• Supports Multiple Disk Formats: Works with various disk image formats such as qcow2, raw, vmdk, and vdi.

• Selective File Copying: Allows selective extraction of files or entire directories from the VM's disk image.

Basic Syntax

virt-copy-out [options] disk_image source_path target_path

• disk_image: The virtual machine disk image from which you want to copy files.

• source_path: The path to the file or directory inside the disk image that you want to copy.

• target_path: The destination path on the local system where you want the file or directory to be copied.

Common Options

• -a, --add: Add a source file or directory for extraction.

• -d, --directory: Specify the target directory where files will be copied.

• -h, --help: Show help information about the command.

• -v, --verbose: Provide detailed output of the operation.

• --list: List the available files in the disk image, without copying them.

• --no-perms: Don't preserve file permissions during the copy operation.

Common Use Cases for virt-copy-out

1. Copy a Single File from a Disk Image

   If you need to extract a single file from a VM disk image:

   virt-copy-out /path/to/disk-image.qcow2 /etc/passwd /tmp/passwd

   This will copy the /etc/passwd file from the virtual machine's disk image (/path/to/disk-image.qcow2) to /tmp/passwd on the host machine.

2. Copy a Directory from a Disk Image

   To copy an entire directory, use the following command:

   virt-copy-out /path/to/disk-image.qcow2 /home/user /tmp/home_user

   This will copy the /home/user directory from the VM disk image to /tmp/home_user on the local filesystem.

3. List Files in a Disk Image

   If you just want to list the files available in a disk image without actually copying them, you can use the --list option:

   virt-copy-out --list /path/to/disk-image.qcow2

   This will display a list of files present in the disk image.

4. Copy Files with Verbose Output

   For more detailed output on the process, use the -v (verbose) option:

   virt-copy-out -v /path/to/disk-image.qcow2 /var/log /tmp/logs

   This will copy the /var/log directory from the disk image to /tmp/logs on the host machine, and display detailed information during the process.

Example Output

If you're copying a file and the operation is successful, you will see output similar to this:

Extracting file /etc/passwd from /path/to/disk-image.qcow2 to /tmp/passwd
File /etc/passwd extracted successfully.

If you use the -v (verbose) option, it might show additional details:

Extracting file /etc/passwd from /path/to/disk-image.qcow2 to /tmp/passwd
Copying /etc/passwd from the image
Finished copying file /etc/passwd to /tmp/passwd

Use Case Scenarios for virt-copy-out

• Recovering Files from a Stopped VM: If you have a VM that is not running but need to recover some files, you can use virt-copy-out to extract them from the VM's disk image.

• Backup and Restore Operations: When you back up VM disk images, you may need to extract specific files for recovery without restoring the entire image. virt-copy-out makes it easy to selectively restore files.

• VM Migration or Cloning: When moving VMs between different environments or systems, you might want to copy certain files out of the image for auditing, troubleshooting, or migration purposes.

Conclusion

virt-copy-out is a powerful and flexible tool that provides administrators with an easy way to extract files from virtual machine disk images. Whether you're recovering files from a stopped VM, performing backup and restore operations, or just need to inspect a VM's filesystem, virt-copy-out is an essential tool for managing virtual environments.