Using less as gdb pager - gdb

Question

I noticed that in GDB, when issuing commands with long output like info variables, the output is displayed one page at time, pressing enter to go down and q to quit.
Is it possible to replace the default pager with another one, such as less, so that I can navigate up and down, quitting, searching, etc?

Answer 1

Is it possible to replace the default pager with another one
No: GDB doesn't call into external program to display the output, it simply pauses the output every screenfull (and you can make it not pause by set height 0).
In addtion to running inside emacs, you could also use screen or tmux (learning them will generally help you in a lot of other situations), or ask GDB to log output (set logging on) and then search in gdb.txt with any $PAGER you want.

Answer 2

Starting with version 9.1, GDB has a pipe command, so you can send a command's output to the pager of your choice. From the documentation:
pipe [command] | shell_command
Executes command and sends its output to shell_command. Note that no space is needed around |. If no command is provided, the last command executed is repeated.

Answer 3

run gdb inside of emacs and you should be able to use emacs' paging commands.
run emacs
type M-x gdb return (M stands for meta - alt key or option on Macs)
The Emacs message bar will now display the message:
Run gdb (like this): gdb
More information is available here: http://tedlab.mit.edu/~dr/gdbintro.html
HTH

Answer 4

you can put the following user-defined commands in ~/.gdbinit, then
% cat ~/.gdbinit
python import os
define less1
python os.popen("less","w").write(gdb.execute("$arg0",to_string=True))
end
define less2
python os.popen("less","w").write(gdb.execute("$arg0 $arg1",to_string=True))
end
...
% gdb
(gdb) less2 info var
...
(gdb) less1 disass
...

Answer 5

It is a bit old thread, but I think it is worth to add. #yichun gave a very nice idea here, but to be more practical it can be extended to any number of arguments:
define less
python import os
python os.popen("less","w").write(gdb.execute(' '.join(["$arg{0}".format(i) for i in range(0, argc)]), to_string=True))
end
Then it can also woth adding exceptions handling and waiting for processes to terminate to avoid keyboard glitches and we have something like that:
% cat ~/.gdbinit
define less
python argc = $argc
python
import os
f = None
try:
f = os.popen("less","w")
f.write(gdb.execute(' '.join(["$arg{0}".format(i) for i in range(0, argc)]), to_string=True))
except Exception as e:
if f:
f.write(str(e))
else:
print (str(e))
finally:
if f:
f.close()
end
end

Answer 6

In gdb 8.1.1 this code in .gdbinit adds the required functionality:
python
import os
class Less(gdb.Command):
def __init__(self):
super().__init__("less", gdb.COMMAND_USER, gdb.COMPLETE_COMMAND)
def invoke(self, argstr, from_tty):
with os.popen("less","w") as pipe:
try:
pipe.write(gdb.execute(argstr, to_string=True))
except Exception as e:
pipe.write(str(e))
Less()
end
Usage
(gdb) less info breakpoints
(gdb) less backtrace
Information: Commands In Python.