Of all the programs I’ve written, perhaps the one that has most directly benefited me is this little bash script in my dotfiles repo which runs the application launcher dmenu showing the most-frequently-used programs first.

The typical way to run dmenu is to pipe the output of dmenu_path into dmenu. Both commands come in the dmenu package. The former simply prints a list of all programs in the user’s path:

$ dmenu_path

The dmenu program reads a list of strings from its standard input and presents a graphical list. The user selects a single item from the list, and dmenu prints the selection to its standard output.

For example:

$ echo -e 'hello\nworld'
$ echo -e 'hello\nworld' | dmenu

The second command displays this GUI at the top of the screen: dmenu-hello-world Use the arrow keys to change the selection or start typing a name to narrow down the list: dmenu-world Hit enter and dmenu exits after printing world to its standard output.

To use it as a program launcher, the dmenu package comes with a third program - a shell script dmenu_run which combines the above two programs. Here’s its source:

dmenu_path | dmenu "$@" | ${SHELL:-"/bin/sh"} &

As an aside, dmenu is a perfect example of a tool which does one thing well, and adds value to an existing set of tools by being easily composable.

Here’s the list I see when I run it: dmenu And after pressing “t”: dmenu-t

Menu items are shown in the order they appeared on dmenu’s stdin, and dmenu_path prints all program’s in the user’s $PATH in alphabetical order. The problem with this is there are only a tiny handful of graphical programs that I ever want to launch with dmenu, and it’s unlikely that they will appear early in the alphabetically-listed program names. dmenu_histogram addresses this by maintaining a histogram of launched programs and placing these programs in order of frequency on dmenu’s stdin before the output of dmenu_path.

Running the dmenu_histogram script: hist …shows a list of programs I commonly use. If I press “t”… hist-t …the list narrows to just the programs starting with “t”, and still shows the most frequent programs first.

To be perfectly clear, I did not develop dmenu. I wrote myself a bash script that invokes dmenu on the output of dmenu_path augmented with a list of common programs ordered by frequency of use, and updates a histogram (in a text file) counting the number of times each program is launched to build a more accurate list for the next invocation.

The histogram it maintains looks like this on my system at the time of writing:

8 xterm
1 xfontsel
2 uxterm
6 st
1 vimdot
7 gimp
15 wifimgr
11 thunderbird
4 pavucontrol
1 mtpaint
2 surf
195 xlock
2 xeyes
5 virtualbox
1 dmenu