runwhenidle

runwhenidle is a Linux utility that can be used to pause a computationally or IO-intensive program when user is in front of the computer, resuming it once the user is away, usually without requiring adaptation from the program being run. It can run a command given to it or monitor an already running process.

Example 1:

The simplest way to start using runwhenidle is just by putting it in front of the command:

runwhenidle rsync -rva /home /backup

Example 2:

runwhenidle --start-monitor-after=10000 --timeout=30 --quiet ffmpeg -i file.mp4 file.mkv

In this example ffmpeg will run for 10 seconds uninterrupted. After 10 seconds pass, runwhenidle will start monitoring user activity and pause ffmpeg if user has been active within last 30 seconds. If user is inactive for 30 seconds, resume the operation of ffmpeg. --quiet option makes sure runwhenidle doesn't output anything other than the output of ffmpeg. Same command can be ran with the short versions of the arguments:

runwhenidle -a 10000 -t 30 -q ffmpeg -i file.mp4 file.mkv

Example 3:

runwhenidle --pid=12345 --pause-method=SIGTSTP --verbose

Start monitoring user activity and when user is active, pause process with PID 12345. Unpause it when user is inactive for 300 seconds. Use SIGTSTP which the process 12345 can handle or ignore instead of the default SIGSTOP that is always handled by the OS.

Under the Hood: How runwhenidle Controls Processes Based on User Activity

runwhenidle uses XScreenSaverQueryInfo() to check when last user activity happened. Therefore, running X server is required. Wayland is not currently supported. When user is active, these checks happen as infrequently as possible to satisfy the desired inactivity timeout (default - every 5 minutes). When user is inactive, these checks happen once per second, to allow to restore the system responsiveness quickly.

When runwhenidle determines that the user is active, it will send SIGSTOP (or optionally SIGTSTP) to the process and all its child processes. When the user activity stops, runwhenidle resumes the process by sending it and all the child processes SIGCONT signal. It then checks once per second if user activity has resumed, and once it is, pauses the process and its child processes again.

If runwhenidle was used to run a command (i.e. --pid parameter was not used) and it receives an interruption signal (SIGINT or SIGTERM), it will resume the process it is running if it is currently paused, and then sned the same signal to it to allow the process to handle the signal. runwhenidle then will stop checking for user activity and will wait for the process to exit.

Installation

Ubuntu and Debian: Download the deb file attached to the latest release.

Arch: Available in AUR: https://aur.archlinux.org/packages/runwhenidle

Other Distros: You will need to compile runwhenidle yourself.

Compiling

Make sure you have gcc, make, git and libxss-dev installed. Run make release. This should produce a binary file runwhenidle in the project directory.

If you want to install it system-wide, run sudo make install or simply sudo cp ./runwhenidle /usr/bin.

Usage

runwhenidle [OPTIONS] [shell_command_to_run] [shell_command_arguments]

Options

Option	Description	Default Value
--timeout, -t <seconds>	Set the user idle time after which the process can be resumed in seconds.	300 seconds
--pid, -p <pid>	Monitor an existing process. When this option is used, shell_command_to_run should not be passed.
--start-monitor-after, -a <ms>	Set an initial delay in milliseconds before monitoring starts. During this time the process runs unrestricted. This helps to catch quick errors.	300 ms
--pause-method, -m <method>	Specify method for pausing the process when the user is not idle. Available Options: SIGTSTP (can be ignored by the program), SIGSTOP (cannot be ignored).	SIGSTOP
--quiet, -q	Suppress all output from ./runwhenidle except errors and only display output from the command that is running. No output if --pid options is used.	Not quiet
--verbose, -v	Enable verbose output for monitoring.	Not verbose
--debug	Enable debugging output.	No debug
--version, -V	Print the program version information.

Known issues

1. Wayland support. runwhenidle currently doesn't work without XScreenSaver, but Wayland support should be possible and is planned (at least for the DEs supporting ext-idle-notify, which now both Gnome and KDE support).
2. When monitoring an existing pid, once it gets paused, it gets detached from the terminal it was in. Running "fg" command could be a workaround to get it reattached, but it is required after every pause.

Building Ubuntu/Debian package

Make sure you have docker installed and run:

make debian-package

The .deb file will be generated in package-build/ directory.