Mailcap

lf works very well with Mailcap as a launcher and a previewer. It is an attractive option once you realize it is already installed on most systems (mailcap is part of the mime-support package, which is a pretty common dependency).

~/.mailcap

The mailcap file allows to define for each MIME types a default action. Example:

video/*; mpv '%s';
audio/*; mpv '%s';
text/*; vim '%s'; needsterminal;

The default action is invoked with run-mailcap file.txt.

We can also define alternate actions like the print action. The print action is invoked with run-mailcap --action=print file.txt or by the default wrapper print file.txt. In the following example we add print actions to our mailcap file with the intent to use print as a lf previewer.

video/*; mpv '%s'; print=mpv --aid=no --vid=no --sid=no '%s' || : ;
audio/*; mpv '%s'; print=mpv --aid=no --vid=no --sid=no '%s' || : ;
text/*; vim '%s'; needsterminal; print=less '%s';

lf integration

In order to use mailcap as a launcher we just need to set the following environment variable:

OPENER=run-mailcap

And in order to use mailcap as a previewer we just need to set the following lf option:

set previewer print