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7.2.13 Invoking guix system

Once you have written an operating system declaration as seen in the previous section, it can be instantiated using the guix system command. The synopsis is:

guix system optionsaction file

file must be the name of a file containing an operating-system declaration. action specifies how the operating system is instantiated. Currently the following values are supported:


Build the operating system described in file, activate it, and switch to it23.

This effects all the configuration specified in file: user accounts, system services, global package list, setuid programs, etc. The command starts system services specified in file that are not currently running; if a service is currently running, it does not attempt to upgrade it since this would not be possible without stopping it first.

This command creates a new generation whose number is one greater than the current generation (as reported by guix system list-generations). If that generation already exists, it will be overwritten. This behavior mirrors that of guix package (see Invoking guix package).

It also adds a GRUB menu entry for the new OS configuration, and moves entries for older configurations to a submenu—unless --no-grub is passed.

Note: It is highly recommended to run guix pull once before you run guix system reconfigure for the first time (see Invoking guix pull). Failing to do that you would see an older version of Guix once reconfigure has completed.


Switch to an existing system generation. This action atomically switches the system profile to the specified system generation. It also rearranges the system’s existing GRUB menu entries. It makes the menu entry for the specified system generation the default, and it moves the entries for the other generations to a submenu. The next time the system boots, it will use the specified system generation.

The target generation can be specified explicitly by its generation number. For example, the following invocation would switch to system generation 7:

guix system switch-generation 7

The target generation can also be specified relative to the current generation with the form +N or -N, where +3 means “3 generations ahead of the current generation,” and -1 means “1 generation prior to the current generation.” When specifying a negative value such as -1, you must precede it with -- to prevent it from being parsed as an option. For example:

guix system switch-generation -- -1

Currently, the effect of invoking this action is only to switch the system profile to an existing generation and rearrange the GRUB menu entries. To actually start using the target system generation, you must reboot after running this action. In the future, it will be updated to do the same things as reconfigure, like activating and deactivating services.

This action will fail if the specified generation does not exist.


Switch to the preceding system generation. The next time the system boots, it will use the preceding system generation. This is the inverse of reconfigure, and it is exactly the same as invoking switch-generation with an argument of -1.

Currently, as with switch-generation, you must reboot after running this action to actually start using the preceding system generation.


Build the derivation of the operating system, which includes all the configuration files and programs needed to boot and run the system. This action does not actually install anything.


Populate the given directory with all the files necessary to run the operating system specified in file. This is useful for first-time installations of GuixSD. For instance:

guix system init my-os-config.scm /mnt

copies to /mnt all the store items required by the configuration specified in my-os-config.scm. This includes configuration files, packages, and so on. It also creates other essential files needed for the system to operate correctly—e.g., the /etc, /var, and /run directories, and the /bin/sh file.

This command also installs GRUB on the device specified in my-os-config, unless the --no-grub option was passed.


Build a virtual machine that contains the operating system declared in file, and return a script to run that virtual machine (VM). Arguments given to the script are passed to QEMU.

The VM shares its store with the host system.

Additional file systems can be shared between the host and the VM using the --share and --expose command-line options: the former specifies a directory to be shared with write access, while the latter provides read-only access to the shared directory.

The example below creates a VM in which the user’s home directory is accessible read-only, and where the /exchange directory is a read-write mapping of $HOME/tmp on the host:

guix system vm my-config.scm \
   --expose=$HOME --share=$HOME/tmp=/exchange

On GNU/Linux, the default is to boot directly to the kernel; this has the advantage of requiring only a very tiny root disk image since the store of the host can then be mounted.

The --full-boot option forces a complete boot sequence, starting with the bootloader. This requires more disk space since a root image containing at least the kernel, initrd, and bootloader data files must be created. The --image-size option can be used to specify the size of the image.


Return a virtual machine or disk image of the operating system declared in file that stands alone. Use the --image-size option to specify the size of the image.

When using vm-image, the returned image is in qcow2 format, which the QEMU emulator can efficiently use. See Running GuixSD in a VM, for more information on how to run the image in a virtual machine.

When using disk-image, a raw disk image is produced; it can be copied as is to a USB stick, for instance. Assuming /dev/sdc is the device corresponding to a USB stick, one can copy the image to it using the following command:

# dd if=$(guix system disk-image my-os.scm) of=/dev/sdc

Return a script to run the operating system declared in file within a container. Containers are a set of lightweight isolation mechanisms provided by the kernel Linux-libre. Containers are substantially less resource-demanding than full virtual machines since the kernel, shared objects, and other resources can be shared with the host system; this also means they provide thinner isolation.

Currently, the script must be run as root in order to support more than a single user and group. The container shares its store with the host system.

As with the vm action (see guix system vm), additional file systems to be shared between the host and container can be specified using the --share and --expose options:

guix system container my-config.scm \
   --expose=$HOME --share=$HOME/tmp=/exchange

Note: This option requires Linux-libre 3.19 or newer.

options can contain any of the common build options (see Common Build Options). In addition, options can contain one of the following:

-s system

Attempt to build for system instead of the host system type. This works as per guix build (see Invoking guix build).


Return the derivation file name of the given operating system without building anything.


For the vm-image and disk-image actions, create an image of the given size. size may be a number of bytes, or it may include a unit as a suffix (see size specifications in GNU Coreutils).


Apply strategy when an error occurs when reading file. strategy may be one of the following:


Report the error concisely and exit. This is the default strategy.


Likewise, but also display a backtrace.


Report the error and enter Guile’s debugger. From there, you can run commands such as ,bt to get a backtrace, ,locals to display local variable values, and more generally inspect the state of the program. See Debug Commands in GNU Guile Reference Manual, for a list of available debugging commands.

Note: All the actions above, except build and init, can use KVM support in the Linux-libre kernel. Specifically, if the machine has hardware virtualization support, the corresponding KVM kernel module should be loaded, and the /dev/kvm device node must exist and be readable and writable by the user and by the build users of the daemon (see Build Environment Setup).

Once you have built, configured, re-configured, and re-re-configured your GuixSD installation, you may find it useful to list the operating system generations available on disk—and that you can choose from the GRUB boot menu:


List a summary of each generation of the operating system available on disk, in a human-readable way. This is similar to the --list-generations option of guix package (see Invoking guix package).

Optionally, one can specify a pattern, with the same syntax that is used in guix package --list-generations, to restrict the list of generations displayed. For instance, the following command displays generations that are up to 10 days old:

$ guix system list-generations 10d

The guix system command has even more to offer! The following sub-commands allow you to visualize how your system services relate to each other:


Emit in Dot/Graphviz format to standard output the service extension graph of the operating system defined in file (see Service Composition, for more information on service extensions.)

The command:

$ guix system extension-graph file | dot -Tpdf > services.pdf

produces a PDF file showing the extension relations among services.


Emit in Dot/Graphviz format to standard output the dependency graph of shepherd services of the operating system defined in file. See Shepherd Services, for more information and for an example graph.



This action (and the related actions switch-generation and roll-back) are usable only on systems already running GuixSD.

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