As a mean to reflect and preserve certain useful commands, I’ll start this little series. Here we go:

Take all JPG files in one folder and reduce their size by 50%.

Get the byzanz-record tool which will create a relatively small GIF of you using your screen to quickly solve a problem and show this to someone else. ffmpeg will convert it to a video in case it is neccessary.

Convert a 12-paged PDF file to 12 single-paged files.

Scan a local network for ssh-enabled devices; useful for finding your Raspberry Pi in a semi-public WLAN.