How to automatically run the executable in GDB?

Question

I'd like to have gdb immediately run the executable, as if I'd typed "run" (motivation: I dislike typing "run").

One way is to pipe the command to gdb like this:

$ echo run | gdb myApp

But the problem with this approach is that you lose interactivity with gdb, eg. if a breakpoint triggers or myApp crashes, gdb quits. This method is discussed here.

Looking at the options in --help, I don't see a way to do this, but perhaps I'm missing something.

score 156 · Accepted Answer · edited May 23 '17 at 12:09

156

gdb -ex run ./a.out

If you need to pass arguments to a.out:

gdb -ex run --args ./a.out arg1 arg2 ...

EDIT: Orion says this doesn't work on Mac OSX.

The -ex flag has been available since GDB-6.4 (released in 2005), but OSX uses Apple's fork of GDB, and the latest XCode for Leopard contains GDB 6.3.50-20050815 (Apple version gdb-967), so you are out of luck.

Building current GDB-7.0.1 release is one possible solution. Just be sure to read this.

edited May 23 '17 at 12:09

Community

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answered Jan 23 '10 at 05:46

Employed Russian

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thanks for the answer. that line behaves the same as just "gdb ./a.out" for me tho. – orion elenzil Jan 25 '10 at 21:50
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I just confirmed that you can also pass multiple -ex options on the command line and they'll run in order before transferring gdb input to you. – Tung Nguyen Jul 19 '12 at 09:06
This solution doesn't work if the program has arguments like: `./a.out a b` – gigilibala Mar 30 '15 at 21:17
since OSX/xcode no longer supports gdb out of the box (lldb is the new gdb), this now seems like the better approach. – orion elenzil Mar 14 '16 at 17:55
I made a command file and use `gdb -x` on Linux systems. OS X uses **LLVM** and **clang** so check out the debugging capabilities of `lldb`. – Daisuke Aramaki Aug 23 '18 at 13:15

score 25 · Answer 2 · 2010-02-13T12:58:38.697

25

I would use a gdb-script:

gdb -x your-script

where your-script contains something like:

file a.out
b main
r

afterwards you have the normal interactive gdb prompt

EDIT:

here is an optimization for the truly lazy:

save the script as .gdbinit in the working directory.
Afterwards you simply run gdb as

gdb

... and gdb automatically loads and executes the content of .gdbinit.

edited Feb 13 '10 at 12:58

answered Jan 22 '10 at 18:44

hey thanks for the answer. that looks like just what i want except i don't get the gdb prompt, i get gdb being suspended and i'm back at the command line as if i'd typed "ctrl-z". if i "fg", then gdb resumes and the app runs. this is OS X. – orion elenzil Jan 25 '10 at 21:48
orion: mmmh - that's surprising to me. Works well with every UNIX flavor I am actually using (Linux, Solaris, AIX). What gdb version you are using? – Feb 08 '10 at 22:06
i just re-verfied the behaviour of this - still exits me to the command line w/ gdb suspended.GNU gdb 6.3.50-20050815 (Apple version gdb-1518) (Sat Feb 12 02:52:12 UTC 2011). – orion elenzil Jun 20 '11 at 05:17
@orionelenzil No idea why, but if you put `fg` after the `r` line, it acts sanely – dbr Dec 19 '12 at 10:08
The `start` command provides a shortcut for `b` + `r`: https://stackoverflow.com/a/2119606/895245 – Ciro Santilli OurBigBook.com Sep 23 '18 at 10:55

score 20 · Answer 3 · answered Jun 19 '11 at 05:01

20

(echo r ; cat) | gdb a.out

The cat allows you keep typing after gdb breaks.

answered Jun 19 '11 at 05:01

cadabra

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whoa, awesome. you have to ctrl-c after exiting gdb to stop the cat, but that's great. – orion elenzil Jun 20 '11 at 05:18
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It looks like you lose some key-control on the gdb instance using this. – Treviño Aug 25 '14 at 20:09
Moreover, questions like `Make breakpoint pending on future shared library load? (y or [n])` will automatically assume answer "No". – Ruslan May 04 '17 at 12:46

Ciro Santilli OurBigBook.com · Answer 4 · 2018-09-23T10:54:46.993

start command

This command is another good option:

gdb -ex start --args ./a.out arg1 arg2

It is like run, but also sets a temporary breakpoint at main and stops there.

This temporary breakpoint is deactivated once it is hit.

starti

There is also a related starti which starts the program and stops at the very first instruction instead, see also: Stopping at the first machine code instruction in GDB

Great when you are doing some low level stuff.

score 4 · Answer 5 · edited Jun 13 '12 at 07:47

4

gdb -x <(echo run) --args $program $args

edited Jun 13 '12 at 07:47

Darshana

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answered Jun 12 '12 at 17:59

Dan

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How to automatically run the executable in GDB?

5 Answers5