Running GDB with args and variables

Running GDB with args and variables

[Mahmood Naderan]

Hi

I use the following command to run a program

$ LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt

Now I want to use 'gdb --args' but the following command doesn't work.


$ gdb --args LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt
...

For help, type "help".
Type "apropos word" to search for commands related to "word"...
LD_PRELOAD=/home/mahmood/foo.so: No such file or directory.
(gdb)




The "No such file" error is weird because the file exists when I run 'ls' command.

Any idea about that?

Regards,
Mahmood

Re: Running GDB with args and variables

[Christian Biesinger]

On Fri, Aug 27, 2021 at 2:29 PM Mahmood Naderan via Gdb
<gdb@sourceware.org> wrote:
> I use the following command to run a program
>
> $ LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt
>
> Now I want to use 'gdb --args' but the following command doesn't work.
>
>
> $ gdb --args LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt
> ...
>
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> LD_PRELOAD=/home/mahmood/foo.so: No such file or directory.
> (gdb)
>
>
>
>
> The "No such file" error is weird because the file exists when I run 'ls' command.
>
> Any idea about that?

I would think the error comes from the fact that gdb is looking for a
file called "LD_PRELOAD=..." and there is no such file.

Maybe try: gdb --args env LD_PRELOAD=... foo

Christian

Re: Running GDB with args and variables

[Luke Drummond]

Hi all
On Mon Aug 30, 2021 at 4:56 PM BST, Christian Biesinger via Gdb wrote:
> On Fri, Aug 27, 2021 at 2:29 PM Mahmood Naderan via Gdb
> <gdb@sourceware.org> wrote:
> > I use the following command to run a program
> > $ LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt
>
> I would think the error comes from the fact that gdb is looking for a
> file called "LD_PRELOAD=..." and there is no such file.
>
> Maybe try: gdb --args env LD_PRELOAD=... foo

To avoid the confusion with the `env` fork/exec without worrying about
`set follow-fork-mode child` the following might be better:

gdb \
    --init-eval-command="set environment LD_PRELOAD=/home/mahmood/foo.so" \
    --args /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt


This commands gdb to set the environment in the child before the child is loaded

All the Best

Luke

-- 
Codeplay Software Ltd.
Company registered in England and Wales, number: 04567874
Registered office: Regent House, 316 Beulah Hill, London, SE19 3HF

Re: Running GDB with args and variables

[Mahmood Naderan]

Right. Both solutions work.

Thanks.

Regards,
Mahmood






On Monday, August 30, 2021, 6:13:11 PM GMT+2, Luke Drummond <luke.drummond@codeplay.com> wrote: 





Hi all
On Mon Aug 30, 2021 at 4:56 PM BST, Christian Biesinger via Gdb wrote:
> On Fri, Aug 27, 2021 at 2:29 PM Mahmood Naderan via Gdb
> <gdb@sourceware.org> wrote:
> > I use the following command to run a program
> > $ LD_PRELOAD=/home/mahmood/foo.so /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt
>
> I would think the error comes from the fact that gdb is looking for a
> file called "LD_PRELOAD=..." and there is no such file.
>
> Maybe try: gdb --args env LD_PRELOAD=... foo

To avoid the confusion with the `env` fork/exec without worrying about
`set follow-fork-mode child` the following might be better:


gdb \

    --init-eval-command="set environment LD_PRELOAD=/home/mahmood/foo.so" \
    --args /home/mahmood/program/run /home/mahmood/p2/bin/p2 -config t.txt


This commands gdb to set the environment in the child before the child is loaded

All the Best

Luke

-- 
Codeplay Software Ltd.
Company registered in England and Wales, number: 04567874
Registered office: Regent House, 316 Beulah Hill, London, SE19 3HF