virt-copy-in

virt-copy-in is a tool provided by libvirt that allows you to copy files or directories from the host system to a virtual machine's disk image. This is especially useful when you need to add files to a virtual machine without booting it or when managing files inside a VM from outside the VM environment.

Key Features of virt-copy-in

• Copy Files to a VM: Allows you to copy files or entire directories from the host system into the disk image of a virtual machine.

• Non-Running VMs: It works with disk images even if the virtual machine is not running.

• Supports Multiple Disk Formats: It can handle various disk image formats like qcow2, raw, vmdk, and vdi.

• Selective File Copying: You can choose specific files or directories to copy into the VM's disk image.

• Preserve File Permissions: By default, it preserves file permissions and attributes when copying files into the VM.

Basic Syntax

virt-copy-in [options] disk_image source_path target_path

• disk_image: The virtual machine disk image where you want to copy the files.

• source_path: The path to the file or directory on the host system that you want to copy.

• target_path: The destination path inside the virtual machine where you want the files to be copied.

Common Options

• -a, --add: Add one or more files or directories for copying into the VM.

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

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

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

• --no-perms: Don’t preserve file permissions when copying files into the VM.

• --list: List the files that can be copied into the disk image, without actually performing the copy operation.

Common Use Cases for virt-copy-in

1. Copy a Single File into a Virtual Machine's Disk Image

   If you need to copy a single file into the VM's disk image:

   virt-copy-in /path/to/disk-image.qcow2 /tmp/myfile.txt /home/user/

   This command will copy the myfile.txt file from the host's /tmp directory into the /home/user/ directory inside the VM.

2. Copy a Directory into a Virtual Machine's Disk Image

   You can also copy an entire directory from the host system to the VM's disk image:

   virt-copy-in /path/to/disk-image.qcow2 /tmp/mydir /home/user/

   This will copy the contents of /tmp/mydir from the host system into the /home/user/ directory inside the VM.

3. Verbose Output During File Copy

   If you need detailed output of the file copy operation, use the -v option:

   virt-copy-in -v /path/to/disk-image.qcow2 /tmp/myfile.txt /home/user/

   This will give you more information about the copy process, helping to troubleshoot or monitor the file transfer.

4. List Available Files for Copying

   If you want to check which files you can copy before performing the actual copy, use the --list option:

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

   This will list the available files inside the disk image but will not copy them.

Example Output

If the operation is successful, you may see an output like this:

Copying /tmp/myfile.txt to /home/user/ inside /path/to/disk-image.qcow2
File /tmp/myfile.txt copied to /home/user/ inside the VM disk image.

If you're using the -v (verbose) option, the output might be more detailed:

Copying file /tmp/myfile.txt from the host to /home/user/ inside the disk image
Finished copying /tmp/myfile.txt to /home/user/ inside the disk image

Use Case Scenarios for virt-copy-in

• Injecting Files into a VM: When you need to inject configuration files, scripts, or other data into a virtual machine's disk image without booting the VM, virt-copy-in allows you to do so.

• File Recovery: If a VM has become inaccessible or the system is not bootable, you can copy recovery tools or important data files from the host system into the VM’s disk image to facilitate repairs or data retrieval.

• Backup and Restore: When restoring data into a VM from a backup, virt-copy-in allows you to copy specific files or directories into the VM's disk image, helping to restore the VM to its previous state.

• Testing or Updating Files in VM Disk: When testing software or configuration changes on a VM, you can easily copy updated files or new versions of files into the VM’s disk image.

Conclusion

virt-copy-in is a versatile and powerful tool for administrators working with virtualized environments. It allows for efficient file copying from the host system to a VM's disk image, whether the VM is running or not. Whether you're performing file injections, recovery tasks, or managing data within a virtual machine, virt-copy-in streamlines the process and ensures that files are copied securely and accurately.