According to the VESA Plug and Display standard, which uses compatible electrical signaling for analog video, the host is supposed to detect a minimally-capable monitor by looking for 75 Ohm termination on the video lines. Anything beyond basic functionality is determined by reading EDID information over the I2C lines. 

Because EDID is so old, the video card may not even bother checking for a monitor without it. You could probably fool the video card into believing a monitor with any desired capability is present with an appropriately programmed I2C EEPROM or microcontroller.

What impedances do graphics cards expect on H-Sync and V-Sync for VGA monitors?
Cron executes whatever program is sent to it in such a fashion that anything written to STDERR causes either the kernel (or cron I'm unsure) to receive SIGPIPE. How does this functionality work? Is cron sending SIGPIPE or is the kernel? How can I get that same effect, without running something in cron? Could someone tell me for instance how to run a Perl script such that

#!/usr/bin/env perl
warn 'foo';
print "bar;


Receives a SIGPIPE when it tries to write 'foo' to STDERR, and never writes 'bar'? I want to see Perl terminate and shell variable $? return 255.
