Red Hat ENTERPRISE LINUX 4 - DEVELOPER TOOLS GUIDE, Manual

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190 Chapter 22. Canned Sequences of Commands
document
commandname
Document the user-defined command
commandname
, so that it can be accessed by
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. Re-
defining the command with
define
does not change the documentation.
help user-defined
List all user-defined commands, with the first line of the documentation (if any) for each.
show user
show user
commandname
Display the gdb commands used to define
commandname
(but not its documentation). If no
commandname
is given, display the definitions for all user-defined commands.
show max-user-call-depth
set max-user-call-depth
The value of
max-user-call-depth
controls how many recursion levels are allowed in user-
defined commands before GDB suspects an infinite recursion and aborts the command.
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.
22.2. User-defined command hooks
You may define hooks , which are a special kind of user-defined command. Whenever you run the
command
foo
, if the user-defined command
hook-foo
exists, it is executed (with no arguments)
before that command.
A hook may also be defined which is run after the command you executed. Whenever you run the
command
foo
, if the user-defined command
hookpost-foo
exists, it is executed (with no arguments)
after that command. Post-execution hooks may exist simultaneously with pre-execution hooks, for the
same command.
It is valid for a hook to call the command which it hooks. If this occurs, the hook is not re-executed,
thereby avoiding infinte recursion.
In addition, a pseudo-command,
stop
exists. Defining (
hook-stop
) makes the associated commands
execute every time execution stops in your program: before breakpoint commands are run, displays
are printed, or the stack frame is printed.
For example, to ignore
SIGALRM
signals while single-stepping, but treat them normally during normal
execution, you could define:
define hook-stop
handle SIGALRM nopass
end
define hook-run