problem with fgets and execvp

[mattholm]

hi, im trying to read input from the user with fgets for example "ls" then use execvp to make the command happen but when i try it nothing happens. what am i missing?

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#define MAXSIZE 10

main()

{
   char *inputString;
   inputString = malloc(MAXSIZE);
   char *const parmList[] = 
   {"/bin/ls", NULL};

   printf("Please enter a string: ");
   fgets(inputString, MAXSIZE, stdin);
   execvp(inputString, parmList);
   free(inputString);
}

[CommonTater]

That depends. Is ... ls /bin/ls ... a valid command? (cause that's what you're sending it)

Does execvp() return an error? (you probably should be checking that)

Also, don't forget that the string entry from fgets() includes the carriage return, so you probably need to strip that out before calling the function.

[jimblumberg]

Your problem is probably the newline character at the end of your input string. Remember fgets() puts the end of line character into the destination string. Also main should be defined to return an int, int main(void).

This works for me:

#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
// Add this include for the strlen() function.
#include <string.h>

#define MAXSIZE 10

int main()

{
   char inputString[MAXSIZE];
   char *const parmList[] =   {"/bin/ls", NULL};

   printf("Please enter a string: ");
   fgets(inputString, MAXSIZE, stdin);
   inputString[strlen(inputString)-1] = '\0';
   execvp(inputString, parmList);
}

Jim