acbuild run will run the given command inside the ACI.
acbuild needs to be able to differentiate between flags to acbuild and flags to
pass along to the binary being run. This is accomplished with --. Any flags
occurring before this are considered as being intended for acbuild, and any
flags after it are assumed to belong to the command being run.
In order to be able to run the command, all dependencies of the current ACI
must be fetched. The first time run is called, the dependencies will be
downloaded and expanded.
acbuild utilizes overlayfs when running a command in an ACI with dependencies. This is so that acbuild is able to separate out the files from the dependencies and the files in your ACI after the command finishes running.
Obviously this is not necessary when there are no dependencies. If acbuild run is to be used on a system without overlayfs, the ACI and its dependencies
must be flattened into a single ACI without dependencies. A command called
acbuild squash is being worked on to do this.
acbuild can use different engines to perform the actual execution of the given
command. The flag --engine can be used to select a non-default engine.
The default engine in acbuild is called systemd-nspawn, which rather
obviously uses systemd-nspawn to run the given command. This means that the
machine running acbuild must have systemd installed to be able to use acbuild run with the default engine.
An alternative engine is called chroot, which uses the chroot syscall to
enter into the container and run the specified command. There's no namespacing
involved, so the command will be able to see and possibly interact with other
processes on the host. This engine notably has no dependency on systemd, unlike
the systemd-nspawn engine.
All acbuild commands can be cancelled with Ctrl+c with the exception of
acbuild run once it has executed systemd-nspawn. To break out of a
system-nspawn call, press Ctrl+] three times.