This chapter describes the scripting features of the Digital Ladebug debugger. Using debugger script commands, you can specify a file to input as debugger commands, send debugger output to a file, or send a transcript of an entire debugging session to a file.
When you start the debugger, it first searches for a file named
.dbxinit in the current directory; if it is not there,
it then searches for it in your home directory. If a .dbxinit
file exists in either directory, the debugger interprets
the contents of the file as a string of debugger commands. You
can customize your debugger environment by adding commands to
your .dbxinit file that set debugger aliases (using
the alias command), debugger variables (using the
set command), and source-code search paths (using the
use command).
Ladebug processes the .dbxinit file using the language
of the main program being debugged. Depending on the language of
that program, there are some situations where the behavior of some
.dbxinit commands may vary. If this is an issue, you
can put a set $lang command in the file to ensure the
expected behavior.
Example 15-1 shows a sample
.dbxinit file.
set $listwindow = 45 alias ls "sh ls -l" stop in main; run
When you invoke the debugger, it executes the commands in the
.dbxinit file without echoing the commands to the
screen. Example 15-2 shows this process
for the sample .dbxinit file.
% ladebug sample
Welcome to the Ladebug Debugger Version 4.0
------------------
object file name: sample
Reading symbolic information ...done
[#1: stop in main ]
[1] stopped at [main:4 0x1200001180]
4 for (i=1 ; i<3 ; i++) {
(ladebug)
You can record both your debugger commands as well as the debugger's
responses into a single file by using the record io
command. The syntax for this command is as follows:
record io filename
The debugger records all input and output starting with the command
following the record io command.
record io
command does not record the output from the program you are
debugging.
To stop recording, you must exit the debugger. If a file already exists with the file name you specify, the debugger appends to the file.
You can record debugger responses to your commands using the
record output command. The syntax for this command
is as follows:
record output filename
Use the record input command to create a file
containing the commands you enter at the debugger prompt. The syntax
for this command is as follows:
record input filename
Use the record input command to create a debugger
script. After creating a file containing a list of debugger
commands, you can request that the debugger execute the commands
in the file using the source command. You can also
use an editor (such as vi or emacs )
to edit the commands listed in the file. Example 15-3 shows how to use the record input
command to record a series of debugger commands in a file named
myscript.
(ladebug) record input myscript
(ladebug) stop in main
[#1: stop in main ]
(ladebug) run
[1] stopped at [main:4 0x120000b14]
4 for (i=1 ; i<3 ; i++) {
(ladebug) next
stopped at [main:5 0x120000b1c]
5 f = factorial(i);
(ladebug) step
stopped at [factorial:13 0x120000bb8]
13 if (i<=1)
(ladebug) where
>0 0x120000bb8 in factorial(i=1) sample.c:13
#1 0x120000b28 in main() sample.c:5
(ladebug) cont
1! = 1
2! = 2
Thread has finished executing
(ladebug) quit
% cat myscript
stop in main
run
next
step
where
cont
quit
%
With the source or playback input
commands, you can read in and execute a file containing debugger
commands. You can create such a file manually using an editor or
automatically using the record input command. The
syntax of the command to read in a file of debugger commands is as
follows:
source filename playback input filename
The file corresponding to the filename argument must be
in the current directory or be preceded by a path specification.
When the debugger executes a script file, the $pimode
debugger variable determines whether the commands are echoed to the
display as they are executed, as follows:
$pimode is set to 0 (the default),
commands read in from a script file are not echoed to the
display.
$pimode is set to 1, the commands are
echoed.
Example 15-4 shows how to execute a
debugger script. Because $pimode is set to 0, only
the command output, and not the commands themselves, echoes to the
display.
(ladebug) source myscript
[#1: stop in main ]
[1] stopped at [main:4 0x120000b14]
4 for (i=1 ; i<3 ; i++) {
stopped at [main:5 0x4001d4]
5 f = factorial(i);
stopped at [factorial:13 0x120000b1c]
13 if (i<=1)
>0 0x120000bb8 in factorial(i=1) sample.c:13
#1 0x120000b28 in main() sample.c:5
1! = 1
2! = 2
Thread has finished executing
%