lemonbar-status

Description

lemonbar-status outputs the system status on standard output.

The program does not take any command line arguments and does not use a configuration file. I do not plan to make this program generally useable. But you are invited to take its source code and adapt it to your own needs.

The information displayed includes

the current title played by the Music Player Daemon,
the mail status,
the active network interface name and the IP address,
the battery status,
the display brightness,
the audio volume,
the current weather and
the current date and time.
MPD status and current song

The display is updated periodically with an interval of 10 seconds. If possible, events generated by the system are intercepted and the information is updated immediately.

Prerequisites

Compilation

To compile the program you presumably must be running OpenBSD (tested on version 6.2), you have a recent X server installation and the json-c library is installed.

Runtime

The following conditions must be met for running the lemonbar-status.

You are running OpenBSD.
Your username is wilfried.
You are running the mpd music player daemon.
Your are using trunk0 as your network connection
Your audio system has an outputs.master and an outputs.master.mute mixer device.
My weather script is installed anywhere in $PATH and executable. It must output its data to $HOME/.config/weather/.

If one of these conditions is not met, the program will either not start up or the corresponding output will be disabled.

Program Structure

If you want to change this program, then this section will give you some rough overview about the structure.

The main() function initializes the information sources and contains a kqueue event loop for processing events. It also starts a thread which processes X events. These events are coupled to the kqueue loop by sending the signals USR1 and USR2 to the process. In this way no mutexes or other means of thread synchronization is needed, as the kqueue already provides it.

Each information source is represented by a set of functions. Usually there is initialization function, e.g. mail_init(), which reserves and prepares the resources needed for reacting on the events in the kqueue loop. Then there are the "info" functions, e.g. mail_info(), which return a string or NULL if the information cannot be displayed.

The enumeration infos determines the output sequence and also the size of the infos array in main() where the strings returned by the *_info() functions are stored.

Remarks

The program grabs the XF86AudioMute, XF86AudioLowerVolume and XF86AudioRaiseVolume keys. Therefore applications will not receive those keys. This is my personal preference. But it can be changed in the X event loop with the xcb_allow_events() function.