virt-log1

Usage

Overview

"virt-log" is a command line tool to display the log files from the named virtual machine (or disk image).

This tool understands and displays both plain text log files (eg. /var/log/messages) and binary formats such as the systemd journal.

To display other types of files, use virt-cat(1). To follow (tail) text log files, use virt-tail(1). To copy files out of a virtual machine, use virt-copy-out(1). To display the contents of the Windows Registry, use virt-win-reg(1).

Examples

Display the complete logs from a guest:

 virt-log -d mydomain | less

Find out what DHCP IP address a VM acquired:

 virt-log -d mydomain | grep 'dhclient.*bound to'

Options

--help

Display brief help.

-a file

--add file

Add file which should be a disk image from a virtual machine. If the virtual machine has multiple block devices, you must supply all of them with separate -a options.

The format of the disk image is auto-detected. To override this and force a particular format use the --format=.. option.

-a URI

--add URI

Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).

--blocksize=512

--blocksize=4096

--blocksize

This parameter sets the sector size of the disk image. It affects all explicitly added subsequent disks after this parameter. Using --blocksize with no argument switches the disk sector size to the default value which is usually 512 bytes. See also "guestfs_add_drive_opts" in guestfs(3).

-c URI

--connect URI

If using libvirt, connect to the given URI. If omitted, then we connect to the default libvirt hypervisor.

If you specify guest block devices directly (-a), then libvirt is not used at all.

-d guest

--domain guest

Add all the disks from the named libvirt guest. Domain UUIDs can be used instead of names.

--echo-keys

When prompting for keys and passphrases, virt-log normally turns echoing off so you cannot see what you are typing. If you are not worried about Tempest attacks and there is no one else in the room you can specify this flag to see what you are typing.

--format=raw|qcow2|..

--format

The default for the -a option is to auto-detect the format of the disk image. Using this forces the disk format for -a options which follow on the command line. Using --format with no argument switches back to auto-detection for subsequent -a options.

For example:

 virt-log --format=raw -a disk.img

forces raw format (no auto-detection) for disk.img.

 virt-log --format=raw -a disk.img --format -a another.img

forces raw format (no auto-detection) for disk.img and reverts to auto-detection for another.img.

If you have untrusted raw-format guest disk images, you should use this option to specify the disk format. This avoids a possible security problem with malicious guests (CVE-2010-3851).

--key SELECTOR

Specify a key for LUKS, to automatically open a LUKS device when using the inspection.

--key NAME:key:KEY_STRING

--key UUID:key:KEY_STRING

--key all:key:KEY_STRING

"NAME" is the libguestfs device name (eg. "/dev/sda1"). "UUID" is the device UUID. "all" means try the key against any encrypted device.

Use the specified "KEY_STRING" as passphrase.

--key NAME:file:FILENAME

--key UUID:file:FILENAME

--key all:file:FILENAME

Read the passphrase from FILENAME.

--key NAME:clevis

--key UUID:clevis

--key all:clevis

Attempt passphrase-less unlocking for the device with Clevis, over the network. Please refer to "ENCRYPTED DISKS" in guestfs(3) for more information on network-bound disk encryption (NBDE).

Note that if any such option is present on the command line, QEMU user networking will be automatically enabled for the libguestfs appliance.

--keys-from-stdin

Read key or passphrase parameters from stdin. The default is to try to read passphrases from the user by opening /dev/tty.

If there are multiple encrypted devices then you may need to supply multiple keys on stdin, one per line.

-v

--verbose

Enable verbose messages for debugging.

-V

--version

Display version number and exit.

-x

Enable tracing of libguestfs API calls.

Exit status

This program returns 0 if successful, or non-zero if there was an error.