dwmblocks-async

A modular statusbar for dwm written in C. You may think of it as i3blocks, but for dwm.

Features

• Modular
• Lightweight
• Suckless
• Blocks are clickable
• Blocks are loaded asynchronously
• Each block can be externally triggered to update itself
• Compatible with i3blocks scripts

Apart from these features, this build of dwmblocks is more optimized and fixes the scroll issue due to which the statusbar flickers on scrolling.

Why dwmblocks?

In dwm, you have to set the statusbar through an infinite loop like this:

while :; do
    xsetroot -name "$(date)"
    sleep 30
done

It may not look bad as it is, but it's surely not the most efficient way when you've got to run multiple commands, out of which only few need to be updated as frequently as the others.

# Displaying an unread mail count in the status bar
while :; do
    xsetroot -name "$(mailCount) $(date)"
    sleep 60
done

For example, I display an unread mail count in my statusbar. Ideally, I would want this count to update every thirty minutes, but since I also have a clock in my statusbar which has to be updated every minute, I can't stop the mail count from being updated every minute.

As you can see, this is wasteful. And since my mail count script uses Gmail's APIs, there's a limit to the number of requests I can make, being a free user.

What dwmblocks does is that it allows you to break up the statusbar into multiple blocks, each of which have their own update interval. The commands in a particular block are only executed once in that interval. Hence, we don't run into our problem anymore.

What's even better is that you can externally trigger updation of any specific block.

Why dwmblocks-async?

Everything I have mentioned till now is offered by the vanilla dwmblocks, which is fine for most users. What sets dwmblocks-async apart from vanilla dwmblocks is the 'async' part. dwmblocks executes the commands of each blocks sequentially which means that the mail and date blocks, from above example, would be executed one after the other. This means that the date block won't update unless the mail block is done executing, or vice versa. This is bad for scenarios where one of the blocks takes seconds to execute, and is clearly visible when you first start dwmblocks.

This is where the dwmblocks-async steps in tells the computer to execute each block asynchronously or simultaneously.

Installation

The installation is simple, just clone this repository, modify config.h appropriately, and then do a sudo make install.

git clone https://github.com/UtkarshVerma/dwmblocks-async.git
vi config.h
sudo make install

Usage

To have dwmblocks-async set your statusbar, you need to run it as a background process on startup. One way is by adding the following to ~/.xinitrc.

# `dwmblocks-async` has its binary named `dwmblocks`
dwmblocks &

Modifying the blocks

You can define your statusbar blocks in config.h. Each block has the following properties:

Property	Value
Command	The command you wish to execute in your block
Update interval	Time in seconds, after which you want the block to update. Setting this to 0 will result in the block never being updated.
Update signal	Signal to be used for triggering the block. Must be a positive integer.

The syntax for defining a block is:

static Block blocks[] = {
    ...
    BLOCK("date", 1800, 1)
    ...
}

Apart from that you can also modify the block delimiters and width of each block as shown.

// Maximum possible length of output from block, expressed in number of characters.
#define CMDLENGTH 50

#define DELIMITER " "

// Adds a trailing delimiter to the statusbar, useful for powerline
#define TRAILING_DELIMITER

Signalling changes

Most statusbars constantly rerun every script every several seconds to update. This is an option here, but a superior choice is giving your module a signal that you can signal to it to update on a relevant event, rather than having it rerun idly.

For example, the volume module has the update signal 5 by default. Thus, running pkill -RTMIN+5 dwmblocks will update it.

You can also run kill -44 $(pidof dwmblocks) which will have the same effect, but is faster. Just add 34 to your typical signal number.

My volume module never updates on its own, instead I have this command run along side my volume shortcuts in dwm to only update it when relevant.

Note that all modules must have different signal numbers.

Clickable modules

Like i3blocks, this build allows you to build in additional actions into your scripts in response to click events. You can check out my statusbar scripts as references for using the $BLOCK_BUTTON variable.

For this feature to work, you need dwm to be patched with statuscmd.

Because dwmblocks-async creates a child process, it messes up the way the original statuscmd patch gets the PID of statusbar. It is necessary to modify the following lines in the definition of getstatusbarpid().

				return statuspid;
		}
	}
-	if (!(fp = popen("pidof -s "STATUSBAR, "r")))
+	if (!(fp = popen("pgrep -o "STATUSBAR, "r")))
		return -1;
	fgets(buf, sizeof(buf), fp);
	pclose(fp);

This modification is backwards-compatible with other versions of dwmblocks as well.

Credits

This work would not have been possible without Luke's build of dwmblocks and Daniel Bylinka's statuscmd patch.