getenv always return NULL in GDB/DDD

getenv always return NULL in GDB/DDD

[Luo, Ginger]

Hello, GDB experts


I try to call getenv in my C code, this can return correct env string in terminal, while it returns NULL in GDB/DDD.


#include <stdlib.h>

#include <string.h>

#include <stdio.h>

void main() {
  char * a = getenv("ANCHOR"); // ANCHOR exists in the terminal
  if (strlen(a)>0)
    printf("%s\n", a);
}


The GDB/DDD is started from the same terminal. Even I "show environment", this env exists.

Anyone any idea?

OS/Tools version info: RHEL Linux hostname1 2.6.32-754.3.5.el6.x86_64 #1 SMP Thu Aug 9 11:56:22 EDT 2018 x86_64 GNU/Linux

GNU gdb (GDB) 7.12

gcc (GCC) 6.3.0
SHELL is tcsh, DDD/GDB is using default settings.

Let me know if you need any further info.

Thanks!
G

Re: getenv always return NULL in GDB/DDD

[Simon Marchi]

On 2018-10-26 05:35, Luo, Ginger wrote:
> Hello, GDB experts
> 
> 
> I try to call getenv in my C code, this can return correct env string
> in terminal, while it returns NULL in GDB/DDD.
> 
> 
> #include <stdlib.h>
> 
> #include <string.h>
> 
> #include <stdio.h>
> 
> void main() {
>   char * a = getenv("ANCHOR"); // ANCHOR exists in the terminal
>   if (strlen(a)>0)
>     printf("%s\n", a);
> }
> 
> 
> The GDB/DDD is started from the same terminal. Even I "show
> environment", this env exists.
> 
> Anyone any idea?
> 
> OS/Tools version info: RHEL Linux hostname1 2.6.32-754.3.5.el6.x86_64
> #1 SMP Thu Aug 9 11:56:22 EDT 2018 x86_64 GNU/Linux
> 
> GNU gdb (GDB) 7.12
> 
> gcc (GCC) 6.3.0
> SHELL is tcsh, DDD/GDB is using default settings.
> 
> Let me know if you need any further info.

I don't see off-hand why this would happen.  One thing to try would be 
"set startup-with-shell off".  If, for some reason, your shell (through 
which the debugged program is ran) messes up with the environment, this 
would bypass it entirely.

Otherwise, as usual, I would recommend trying the latest version of GDB. 
  I don't have anything specific in mind that changed recently, but it's 
good to try.

Simon

RE: getenv always return NULL in GDB/DDD

[Luo, Ginger]

Simon,

Thanks, It's awesomely working.

-----Original Message-----
From: Simon Marchi <simon.marchi@polymtl.ca> 
Sent: Friday, October 26, 2018 10:21 PM
To: Luo, Ginger <Ginger.Luo@amd.com>
Cc: gdb@sourceware.org
Subject: Re: getenv always return NULL in GDB/DDD

On 2018-10-26 05:35, Luo, Ginger wrote:
> Hello, GDB experts
> 
> 
> I try to call getenv in my C code, this can return correct env string 
> in terminal, while it returns NULL in GDB/DDD.
> 
> 
> #include <stdlib.h>
> 
> #include <string.h>
> 
> #include <stdio.h>
> 
> void main() {
>   char * a = getenv("ANCHOR"); // ANCHOR exists in the terminal
>   if (strlen(a)>0)
>     printf("%s\n", a);
> }
> 
> 
> The GDB/DDD is started from the same terminal. Even I "show 
> environment", this env exists.
> 
> Anyone any idea?
> 
> OS/Tools version info: RHEL Linux hostname1 2.6.32-754.3.5.el6.x86_64
> #1 SMP Thu Aug 9 11:56:22 EDT 2018 x86_64 GNU/Linux
> 
> GNU gdb (GDB) 7.12
> 
> gcc (GCC) 6.3.0
> SHELL is tcsh, DDD/GDB is using default settings.
> 
> Let me know if you need any further info.

I don't see off-hand why this would happen.  One thing to try would be "set startup-with-shell off".  If, for some reason, your shell (through which the debugged program is ran) messes up with the environment, this would bypass it entirely.

Otherwise, as usual, I would recommend trying the latest version of GDB. 
  I don't have anything specific in mind that changed recently, but it's good to try.

Simon