How to use execvp()

Question

The user will read a line and i will retain the first word as a command for execvp.

Lets say he will type "cat file.txt" ... command will be cat . But i am not sure how to use this execvp(), i read some tutorials but still didn't get it.

#include <stdio.h> #include <stdlib.h>  int main() {     char *buf;     char command[32];     char name[32];     char *pointer;     char line[80];     printf(">");      while((buf = readline(""))!=NULL){            if (strcmp(buf,"exit")==0)         break;          if(buf[0]!=NULL)         add_history(buf);          pointer = strtok(buf, " ");         if(pointer != NULL){             strcpy(command, pointer);         }          pid_t pid;          int  status;          if ((pid = fork()) < 0) {                  printf("*** ERROR: forking child process failed\n");             exit(1);         }         else if (pid == 0) {                       if (execvp(command, buf) < 0) {                      printf("*** ERROR: exec failed\n");                 exit(1);             }         }         else                                           while (wait(&status) != pid)                    ;         free(buf);         printf(">");     }///end While     return 0; } 

Answer 1

The first argument is the file you wish to execute, and the second argument is an array of null-terminated strings that represent the appropriate arguments to the file as specified in the man page.

For example:

char *cmd = "ls"; char *argv[3]; argv[0] = "ls"; argv[1] = "-la"; argv[2] = NULL;  execvp(cmd, argv); //This will run "ls -la" as if it were a command