Gdb print to file instead of stdout

Question

I am running gdb and want to examine one of those unfortunate god objects. It takes many pages (and I have a 24\" monitor turned sideways!) to see the whole thing. For eas

Answer 1

A simple method to log gdb to a file while still seeing the output (which eases writing commands) is to use tee:

gdb command |& tee gdb.log

Answer 2

Although there are many good answers here, I still have to post the only thing that worked for me:

[niko@my-laptop]# gdb MyBinary 2>&1 log.txt

This was the only way to get gdb and binary output into the same log.txt file, while also seeing it on the console.

EDIT:

Caution: Output seems to be partially not synced among the gdb output and the binary output. Can someone confirm? You might want to check whether your telnet/ssh client has a function to log the output that you see in your console.

Answer 3

You've had multiple answers here. They are corrects. I just want to add a command that will help you to collect all the output at once. This really helpful when your collecting a huge backtrace. Before doing any logging configuration, do this:

(gdb)set height 0

I found it on this article: https://askaralikhan.blogspot.com/2016/05/gdb-all-threads-bt-to-file.html?showComment=1584614942454#c4584028195226351332

Answer 4

From https://sourceware.org/gdb/onlinedocs/gdb/Logging-Output.html:

You may want to save the output of gdb commands to a file. There are several commands to control gdb's logging.

set logging on

Enable logging.

set logging off

Disable logging.

set logging file file

Change the name of the current logfile. The default logfile is gdb.txt.

set logging overwrite [on|off]

By default, gdb will append to the logfile. Set overwrite if you want set logging on to overwrite the logfile instead.

set logging redirect [on|off]

By default, gdb output will go to both the terminal and the logfile. Set redirect if you want output to go only to the log file.

show logging

Show the current values of the logging settings.

Answer 5

I've found that you can redirect the output from gdb to a file via the run command:

(gdb) run > outfile

Answer 6

You need to enable logging.

(gdb) set logging on

You can tell it which file to use.

(gdb) set logging file my_god_object.log

And you can examine current logging configuration.

(gdb) show logging