Every so often I mess with [old Linux distros](https://zerker.ca/photos/#15597798463055) or BSDs and do not always have one of the modern screenshot tools available.
Enter xwd. This tool will dump an X11 window (or the root window) to a file for later viewing.
To dump a specific window (click the window after running):
$ xwd -out dump.xwd
To dump the screen (i.e. root window):
$ xwd -root -out dump.xwd
The XWD format is understood by a number of tools, including ImageMagick and GIMP among others. If imagemagick is installed, the following script could be bound to a key for quick and easy screenshots, where the destination path is provided to the script:
#!/bin/sh datename=`date +%Y%m%d-%H%M%S` outpath=/var/tmp/$datename.xwd pngpath=$1/$datename.png xwd -root -out $outpath convert $outpath $pngpath rm $outpath