Writing CGI using UNIX-C
pei pei
the cgi is written using unix-c....
Can I use popen, exec or other?
But when i used exec, my program will always core dump why?
I hope someone could give me the solutions... it is very urgent coz i have
to hand out my project soon... i have tried so many alternative ways but
failed...
Thanks for your help...
Lawrence Kirby
car...@tm.net.my "pei pei" writes:
>How can a cgi program call another C program...
>the cgi is written using unix-c....
>Can I use popen, exec or other?
>But when i used exec, my program will always core dump why?
The standard C library provides only one function to run another program
(or system command) and that is system(). Anything else is platform-
specific. The best place to discuss popen, exec*() etc. is
comp.unix.programmer.
--
-----------------------------------------
Lawrence Kirby | fr...@genesis.demon.co.uk
Wilts, England | 7073...@compuserve.com
-----------------------------------------
F. Paul Menard
Following is from MS C++ 5.0. I think MOST C cpoilers support the exec*
family of functions.
_execl, _wexecl
Load and execute new child processes.
int _execl( const char *cmdname, const char *arg0, ... const char *argn,
NULL );
int _wexecl( const wchar_t *cmdname, const wchar_t *arg0, ... const wchar_t
*argn, NULL );
Function
Required Header
Optional Headers
Compatibility
_execl
<process.h>
<errno.h>
Win 95, Win NT
_wexecl
<process.h> or <wchar.h>
<errno.h>
Win NT
For additional compatibility information, see Compatibility in the
Introduction.
Libraries
LIBC.LIB
Single thread static library, retail version
LIBCMT.LIB
Multithread static library, retail version
MSVCRT.LIB
Import library for MSVCRT.DLL, retail version
Return Value
If successful, these functions do not return to the calling process. A
return value of –1 indicates an error, in which case the errno global
variable is set.
errno Value
Description
E2BIG
The space required for the arguments and environment settings exceeds 32K.
EACCES
The specified file has a locking or sharing violation.
EMFILE
Too many files open (the specified file must be opened to determine whether
it is executable).
ENOENT
File or path not found.
ENOEXEC
The specified file is not executable or has an invalid executable-file
format.
ENOMEM
Not enough memory is available to execute the new process; or the available
memory has been corrupted; or an invalid block exists, indicating that the
calling process was not allocated properly.
Parameters
cmdname Path of file to be executed
arg0, ... argn List of pointers to parameters
Remarks
Each of these functions loads and executes a new process, passing each
command-line argument as a separate parameter.
Example
/* EXEC.C illustrates the different versions of exec including:
* _execl _execle _execlp _execlpe
* _execv _execve _execvp _execvpe
*
* Although EXEC.C can exec any program, you can verify how
* different versions handle arguments and environment by
* compiling and specifying the sample program ARGS.C. See
* SPAWN.C for examples of the similar spawn functions.
*/
#include <stdio.h>
#include <conio.h>
#include <process.h>
char *my_env[] = /* Environment for exec?e */
{
"THIS=environment will be",
"PASSED=to new process by",
"the EXEC=functions",
NULL
};
void main()
{
char *args[4], prog[80];
int ch;
printf( "Enter name of program to exec: " );
gets( prog );
printf( " 1. _execl 2. _execle 3. _execlp 4. _execlpe\n" );
printf( " 5. _execv 6. _execve 7. _execvp 8. _execvpe\n" );
printf( "Type a number from 1 to 8 (or 0 to quit): " );
ch = _getche();
if( (ch < '1') || (ch > '8') )
exit( 1 );
printf( "\n\n" );
/* Arguments for _execv? */
args[0] = prog;
args[1] = "exec??";
args[2] = "two";
args[3] = NULL;
switch( ch )
{
case '1':
_execl( prog, prog, "_execl", "two", NULL );
break;
case '2':
_execle( prog, prog, "_execle", "two", NULL, my_env );
break;
case '3':
_execlp( prog, prog, "_execlp", "two", NULL );
break;
case '4':
_execlpe( prog, prog, "_execlpe", "two", NULL, my_env );
break;
case '5':
_execv( prog, args );
break;
case '6':
_execve( prog, args, my_env );
break;
case '7':
_execvp( prog, args );
break;
case '8':
_execvpe( prog, args, my_env );
break;
default:
break;
}
/* This point is reached only if exec fails. */
printf( "\nProcess was not execed." );
exit( 0 );
}
Process and Environment Control Routines | _exec, _wexec_Function Overview
See Also abort, atexit, exit, _onexit, _spawn Function Overview, system
FPM
pei pei wrote in message <01be31ab$2e01ef80$7db8...@caryn75.tm.net.my>...
>How can a cgi program call another C program...
>the cgi is written using unix-c....
>Can I use popen, exec or other?
>But when i used exec, my program will always core dump why?
>
>