a

a [
line
] 
command

Sets an action to be done before the line is executed. The following steps are taken:

• Checks for a breakpoint at this line.

• Prints the line if necessary.

• Performs any actions associated with the line.

• Prompts the user if at a breakpoint or in single-step mode.

• Evaluates the line.

For example, the following prints the value of $foo (and " DB FOUND ") every time line 53 is passed:

a 53 print "DB FOUND $foo\n"