In custom_postgui.hal ?

$ halcmd help
Use 'help <command>' for more details about each command
Available commands:
  loadrt              Load realtime module(s)
  loadusr             Start user space program
  waitusr             Waits for userspace component to exit
  unload              Unload realtime module or terminate userspace component
  lock, unlock        Lock/unlock HAL behaviour
  linkps              Link pin to signal
  linksp              Link signal to pin
  net                 Link a number of pins to a signal
  unlinkp             Unlink pin
  newsig, delsig      Create/delete a signal
  getp, gets          Get the value of a pin, parameter or signal
  ptype, stype        Get the type of a pin, parameter or signal
  setp, sets          Set the value of a pin, parameter or signal
  addf, delf          Add/remove function to/from a thread
  show                Display info about HAL objects
  list                Display names of HAL objects
  source              Execute commands from another .hal file
  status              Display status information
  save                Print config as commands
  start, stop         Start/stop realtime threads
  alias, unalias      Add or remove pin or parameter name aliases
  echo, unecho        Echo commands from stdin to stderr
  quit, exit          Exit from halcmd

$ man halcmd