How to implement a kill command in my own shell - c

Question

I'm trying to create my shell in C, but I don't know how to implement the kill function.
I can't use the command kill(), I want to create my own function by insert for exemple " k process_pid ".
Here my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#define maxarg 20
void CtrlC(int sig);
void execute(char *argv[]);
char getargs(int *argcp, char *argv[], int max);
int main () {
signal(SIGINT,CtrlC);
char *argv[maxarg+1];
int argc;
while (1) {
printf(">");
if(!getargs(&argc, argv, maxarg) || argc == 0) {
continue;
}
if(strncmp(argv[0], "exit", 4) == 0) {
printf("Program completed.\n");
exit(0);
}
execute(argv);
}
}
char getargs(int *argcp, char *argv[], int max){
static char cmd[100];
char *cmdp;
int i;
if(gets(cmd) == NULL)
exit(0);
cmdp = cmd;
for(i=0; i<=max; i++){
if((argv[i] = strtok(cmdp, " \t")) == NULL)
break;
cmdp = NULL;
}
if(i > max){
printf(">Too many arguments!\n");
return -1;
}
*argcp = i;
return(1);
}
void execute(char *argv[]) {
int i;
switch (fork()) {
case -1:
printf(">Error in the creation of the process.\n");
return;
case 0:
execvp(argv[0], argv);
printf(">Can't execute.\n");
perror(">execvp");
exit(1);
default:
if(wait(NULL) == -1)
perror(">Wait");
}
}
void CtrlC (int sig) {
signal(sig, SIG_IGN);
printf("\n>To exit digit 'exit'.\n>");
signal(SIGINT,CtrlC);
fflush(stdout);
}

Answer 1

Exactly what you did with the exit command, you just have to:
test for !strncmp(argv[0],"k",1)
then decode the pid with sscanf(argv[1],"%d",&pid)
then kill it with kill(pid,SIGTERM) (or any other signal you want)