xawt

xawt - X11 active window trigger

• run shell commands when a window receives or loses focus
• optional delay
• optional retry period for failed commands

I use it to prevent too many idling virtualbox guests from surreptitiously stealing cpu cycles.

install globally and run

With node.js installed on the target X11 box:

$ npm install -g xawt            # might need to prefix with sudo
$ xawt

You should see echo commands run whenever the window focus changes.

configure

On its first run xawt copies the default configuration file to $XDG_CONFIG_HOME/xawt.conf which defaults to $HOME/.config/xawt.conf. Edit this leanconf file with one or more rules:

/regex/:
  in: action
  out: action

• regex : a unique JavaScript regular expression

• in: : (optional) action to perform when regex matches the title of a window receiving focus (activating).

• out: : (optional) action to perform when regex matches the title of a window losing focus (de-activating).

• action : either the shell command to run immediately, or

  command: shell-command
  delay: delay-secs
  retry: retry-secs
  

  • delay: : (optional) number of seconds to wait before running the shell command, as long as the window's focus remains unchanged. If not supplied, a value of 0 is used.
  • retry: : (optional) number of seconds to wait before retrying a failed shell command. If not supplied, a failed command is never retried.

Commands can include parenthesised substring matches by the $ symbol where $1 is the first submatch, $2 the second, etc.

# xawt.conf example configuration

# freeze Firefox (after 10 seconds) unless it has the focus
/- (Mozilla Firefox|Vimperator)$/:
  in: pkill -CONT firefox
  out:
    command: pkill -STOP firefox
    delay: 10

# unpause any virtualbox guest immediately on gaining focus
/^(\w+) \[Paused\] - Oracle VM VirtualBox$/:
  in: vboxmanage controlvm $1 resume

# unconditionally pause virtualbox guest 30 seconds after losing focus
/^(HERBERT|SANDPIT) \[Running\] - Oracle VM VirtualBox$/:
  out:
    command: vboxmanage controlvm $1 pause
    delay: 30

# pause virtualbox guest 60 seconds after losing focus unless vlc is running,
# in which case keep retrying every 90 seconds until vlc closes.
/^(SWEEP) \[Running\] - Oracle VM VirtualBox$/:
  out:
    command: (! vboxmanage guestcontrol $1 run --wait-stdout --exe /bin/pgrep -- arg0 vlc) && vboxmanage controlvm $1 pause
    delay: 60
    retry: 90

options

$ xawt --help
Usage: xawt [Options]

Options:

  -h, --help                output usage information
  -V, --version             output the version number
  -c, --config-path [path]  path to configuration file (default:~/.config/xawt.conf)
  -d, --dry-run             trace commands without executing
  -v, --verbose             emit detailed trace for debugging

developer build and run

$ git clone --branch=dev https://github.com/dizzib/xawt.git
$ cd xawt
$ npm install     # install dependencies
$ npm test        # build all and run tests
$ npm start       # start the task runner and dry-run xawt

license

MIT