host-spawn

Run commands on your host machine from inside your flatpak sandbox, toolbox or distrobox containers.

Originally started as a reimplementation of flatpak-spawn --host.

Recommended setup

Note: Distrobox already ships with host-spawn. You might be better served by using their wrapper distrobox-host-exec which runs host-spawn under the hood.

• Install host-spawn in a location visible only to the container. I recommend /usr/local/bin.
• Make sure it is executable with chmod +x host-spawn

How to use

• host-spawn with no argument will open a shell on your host.
• host-spawn command... will run the command on your host.

Run host-spawn -h for more options.

Creating shims for host binaries

If there's a process that you always want to execute on the host system, you can create a symlink to it somewhere in your $PATH and it'll always be executed through host-spawn.

Example of creating a shim for the flatpak command:

# Inside your container:

$ flatpak --version
zsh: command not found: flatpak

# Have host-spawn handle any flatpak command
$ ln -s /usr/local/bin/host-spawn /usr/local/bin/flatpak

# Now flatpak will always be executed on the host
$ flatpak --version
Flatpak 1.12.7

Note: you will want to store the symlink in a location visible only to the container, to avoid an infinite loop. If you are using toolbox/distrobox, this means anywhere outside your home directory. I recommend /usr/local/bin.

Improvements over flatpak-spawn --host

• Allocates a pty for the spawned process, fixing the following upstream issues: flatpak/flatpak#3697, flatpak/flatpak#3285 and flatpak/flatpak-xdg-utils#57
• Handles SIGWINCH (terminal size changes)
• Passes through $TERM environment variable
• Shims host binaries when symlinked, see section above