That is one of the defaults that ships with plan9. Any text of the form [A-z0-9/_.,-]+:[0-9]+ I..e a path with a line number - e.g. /sys/src/lib9/9.h:5

That is one of the defaults that ships with plan9. Any text of the form [A-z0-9/_.,-]+:[0-9]+ I..e a path with a line number - e.g. /sys/src/lib9/9.h:5 Will open that file in your editor at that line. The plan9 utiiities, such as grep -n, will present filenames with line numbers in that form. It is trivial to add your own such that Error X in file /path/to/file on line 5 Will do the same. Before plan9 had a usable html4 renderer I would send URLs to a listener on a Unix machine with firefox to open them there inside my VNC session.