A user-defined command is a sequence of GDB commands to
which you assign a new name as a command. This is done with the
define
command. User commands may accept up to 10 arguments
separated by whitespace. Arguments are accessed within the user command
via $arg0...$arg9. A trivial example:
define adder print $arg0 + $arg1 + $arg2
To execute the command use:
adder 1 2 3
This defines the command adder
, which prints the sum of
its three arguments. Note the arguments are text substitutions, so they may
reference variables, use complex expressions, or even perform inferior
functions calls.
define commandname
define
command. The end of these
commands is marked by a line containing end
.
if
else
, followed
by a series of commands that are only executed if the expression
was false. The end of the list is marked by a line containing end
.
while
if
: the command takes a single argument,
which is an expression to evaluate, and must be followed by the commands to
execute, one per line, terminated by an end
.
The commands are executed repeatedly as long as the expression
evaluates to true.
document commandname
help
. The command commandname must already be
defined. This command reads lines of documentation just as define
reads the lines of the command definition, ending with end
.
After the document
command is finished, help
on command
commandname displays the documentation you have written.
You may use the document
command again to change the
documentation of a command. Redefining the command with define
does not change the documentation.
help user-defined
show user
show user commandname
When user-defined commands are executed, the commands of the definition are not printed. An error in any command stops execution of the user-defined command.
If used interactively, commands that would ask for confirmation proceed without asking when used inside a user-defined command. Many GDB commands that normally print messages to say what they are doing omit the messages when used in a user-defined command.
Go to the first, previous, next, last section, table of contents.