.bp 
.au "TSC \- intro.xx"

.c
The zap Program

.2
\f(BIzap\fB is a Perl version of that old program to 
send signals to a selected set of processes.

.2
This one lets you send a signal based according to 
tty, command name, or user (plus others).  Which one
you mean is inferred.

.2
The choice of names for variables here was inspired
due to a lack of data structures before Perl 5.  
This makes the program trickier than it needs to be.

.2
Notice how 
.T eval 
is used to check for a valid regexp.

.2
This program behaves differently when called by a different name.