A young Unix administrator asked me why a mail he was sending from one of his
systems appeared to be from a strange
000-Admin user. I told him that his
MUA was adding the value of the gecos field to the sender. A blank look on
his face showed he knew nothing of gecos. Do young people not learn a bit of
history? Even Wikipedia describes the gecos field.
some early Unix systems at Bell Labs used GCOS machines for print spooling and various other services. The field added to "/etc/passwd" to carry GCOS ID information was called the "GECOS field" and survives today as the "pw_gecos" member used for the user's full name and other human-ID information.
I wasn't involved in the days of GCOS machines, but I do know a bit of the history. I must be getting old...