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 applications from surreptitiously stealing cpu cycles, but you may find it useful in other ways.

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