many pipes in a shell program - shell

Question

I have to create support for one or more pipes in my shell, for example:ls /tmp | wc -l or sort foo | uniq -c | wc -l. But I have no idea how to do it. I have read many tutorials but I can't adjust what I read in my code.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#define MAX_CMD_LENGTH 100
#define MAX_NUM_PARAMS 10
int parsecmd(char* cmd, char** params) { //split cmd into array of params
int i,n=-1;
for(i=0; i<MAX_NUM_PARAMS; i++) {
params[i] = strsep(&cmd, " ");
n++;
if(params[i] == NULL) break;
}
return(n);
};
int executecmd(char** params) {
pid_t pid = fork(); //fork process
if (pid == -1) { //error
char *error = strerror(errno);
printf("error fork!!\n");
return 1;
} else if (pid == 0) { // child process
execvp(params[0], params); //exec cmd
char *error = strerror(errno);
printf("unknown command\n");
return 0;
} else { // parent process
int childstatus;
waitpid(pid, &childstatus, 0);
return 1;
}
};
int execpipe (char ** argv1, char ** argv2) {
int fds[2];
pipe(fds);
int i;
pid_t pid = fork();
if (pid == -1) { //error
char *error = strerror(errno);
printf("error fork!!\n");
return 1;
}
if (pid == 0) { // child process
close(fds[1]);
dup2(fds[0], 0);
//close(fds[0]);
execvp(argv2[0], argv2); // run command AFTER pipe character in userinput
char *error = strerror(errno);
printf("unknown command\n");
return 0;
} else { // parent process
close(fds[0]);
dup2(fds[1], 1);
//close(fds[1]);
execvp(argv1[0], argv1); // run command BEFORE pipe character in userinput
char *error = strerror(errno);
printf("unknown command\n");
return 0;
}
};
int main() {
char cmd[MAX_CMD_LENGTH+1];
char * params[MAX_NUM_PARAMS+1];
char * argv1[MAX_NUM_PARAMS+1] = {0};
char * argv2[MAX_NUM_PARAMS+1] = {0};
int k, y, x;
int f = 1;
while(1) {
printf("$"); //prompt
if(fgets(cmd, sizeof(cmd), stdin) == NULL) break; //read command, ctrl+D exit
if(cmd[strlen(cmd)-1] == '\n') { //remove newline char
cmd[strlen(cmd)-1] = '\0';
}
int j=parsecmd(cmd, params); //split cmd into array of params
if (strcmp(params[0], "exit") == 0) break; //exit
for (k=0; k <j; k++) { //elegxos gia uparksi pipes
if (strcmp(params[k], "|") == 0) {
f = 0; y = k;
printf("pipe found\n");
break;
}
}
if (f==0) {
for (x=0; x<k; x++) {
argv1[x]=params[x];
}
int z = 0;
for (x=k+1; x< j; x++) {
argv2[z]=params[x];
z++;
}
if (execpipe(argv1, argv2) == 0) break;
} else if (f==1) {
if (executecmd(params) == 0) break;
}
} // end while
return 0;
}