Обсуждение: Executing Shell Command

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Executing Shell Command

От
"Nicholas Walker"
Дата:

I have been trying to execute a shell command from within postgresql

 

My C Function

 

#include <stdlib.h>

#include<postgres.h>

 

 

 void shell_exec(text arg)

 {

     system(arg.vl_dat);

 }

 

The function in postgres

 

CREATE FUNCTION xp_shellexec(text) RETURNS void

      AS '/home/psql/cfuncs/shellexec', 'shell_exec'

      LANGUAGE C STRICT;

 

Then run SELECT xp_shellexec(‘mkdir /home/psql/testing’)

 

No error message, it runs, but the directory isn’t created.

 

The C function works if I compile it, and run myself from the shell,

And I even just tried doing this:

void shell_exec(text arg)

 {

     system(“mkdir /home/psql/testing”);

 }

 

and it still didn’t work…

the directory has rwx permissions for everyone

I am running freebsd 5.1, and the most recent version of postgres

 

Can someone give me some help?

 

Thanks

 

 

 

Re: Executing Shell Command

От
Bruce Momjian
Дата:
Wow, you got me on this one.  You checked the permissions, and even
tried a hard-coded string.  Have you looked in the server logs to see if
it has any more information?

---------------------------------------------------------------------------

Nicholas Walker wrote:
> I have been trying to execute a shell command from within postgresql
>
> My C Function
>
> #include <stdlib.h>
> #include<postgres.h>
>
>
>  void shell_exec(text arg)
>  {
>      system(arg.vl_dat);
>  }
>
> The function in postgres
>
> CREATE FUNCTION xp_shellexec(text) RETURNS void
>       AS '/home/psql/cfuncs/shellexec', 'shell_exec'
>       LANGUAGE C STRICT;
>
> Then run SELECT xp_shellexec('mkdir /home/psql/testing')
>
> No error message, it runs, but the directory isn't created.
>
> The C function works if I compile it, and run myself from the shell,
> And I even just tried doing this:
> void shell_exec(text arg)
>  {
>      system("mkdir /home/psql/testing");
>  }
>
> and it still didn't work.
> the directory has rwx permissions for everyone
> I am running freebsd 5.1, and the most recent version of postgres
>
> Can someone give me some help?
>
> Thanks
>
>
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Re: Executing Shell Command

От
Joe Conway
Дата:
Nicholas Walker wrote:
> I have been trying to execute a shell command from within postgresql

You ought to be using Version 1 calling conventions -- see:
http://www.postgresql.org/docs/current/static/xfunc-c.html#AEN29226

The following works fine for me on RH9:

#define GET_STR(textp) \
   DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(textp)))
extern Datum shell_exec(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(shell_exec);
Datum
shell_exec(PG_FUNCTION_ARGS)
{
     char   *cmd = GET_STR(PG_GETARG_TEXT_P(0));
     int32   result;
     result = system(cmd);
     PG_RETURN_INT32(result);
}


CREATE OR REPLACE FUNCTION xp_shellexec(text)
RETURNS int
AS '$libdir/shell_exec','shell_exec'
LANGUAGE 'C' VOLATILE STRICT;

SELECT xp_shellexec('mkdir /tmp/testing123');

[root@dev tmp]# ls -ld /tmp/test*
drwx------    2 postgres postgres     4096 Nov 28 19:31 /tmp/testing123


HTH,

Joe