Using the exec call function to execute an app
Im just wondering how i can pass multiple parameters in this instance:
Prompt the user to enter a program name and then input multiple parameters:
e.g:Program Name: ls, First Parameter: -l (and so on....)
so... Program var is : ls, parameter var 1 = -l, parameter var 2 = -p, etc. ......
I need to use the execlp or an alternative call.Code:char program[256]; char *parameters=NULL; execlp(program,program,parameters, (char *)0);
Thanks
I have looked around for the solution but cant get my code to work, can you help?
The code you posted will obviously not do anything. Is that what you have tried? If not, post what you are actually doing, and someone can correct it.Originally Posted by it01y2
ps. "NULL" will suffice in place of (char*)0.
C programming resources:
GNU C Function and Macro Index -- glibc reference manual
The C Book -- nice online learner guide
Current ISO draft standard
CCAN -- new CPAN like open source library repository
3 (different) GNU debugger tutorials: #1 -- #2 -- #3
cpwiki -- our wiki on sourceforge
Code:#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <string.h> #include "simpleio.h" int main(int arc, char **argv, char **envp) { int i, repetitions,separator; char *result=NULL; char input[256]; char *arg_list=NULL; char program[256]; printf("Dmush$: "); getString(input,256); int x=0; result = strtok( input, " "); while( result != NULL ) { if(x ==0) { strcpy(program,result); } else { arg_list = result; } x++; result = strtok( NULL, " "); } execlp(program,program,arg_list,(char *)0); /* Access Child */ printf("Dmush$: Error - Unknown command '%s'\n",program); }
Last edited by it01y2; 12-20-2009 at 11:07 AM.
Unfortunately, that's not the case. Because execlp() take a variable number of arguments, no conversions apart from the usual arithmetic conversions are done. If NULL is (void*) then it'll probably work (I don't believe that void* and char* are required to be passed in the same way, but I'd be shocked if there were a system where they aren't); but if NULL is 0 then you're passing an int where execlp() expects a char*, and if these are different sizes, it's a real problem."NULL" will suffice in place of (char*)0.
This is one of those rare cases where a cast is needed; either (char *)NULL or (char *)0.
