gcc -Wall help.c -o help
help.c: In function ‘findpid':
help.c:29:25: warning: passing argument 2 of ‘strncat' from incompatible pointer type
           strncat( pro, &str, 60);
                         ^
In file included from help.c:3:0:
/usr/include/string.h:140:14: note: expected ‘const char * __restrict__' but argument is of type ‘char (*)[60]'
 extern char *strncat (char *__restrict __dest, const char *__restrict __src,
              ^

#include <stdio.h>
#include <dirent.h>
#include <string.h>

void findpid(char *filename){

    char pro[60] = "/proc/";
    char fd[5] = "/fd/";
    char pid[7];
    char str[60];
    char dir[60];
    FILE *file;
    file = fopen(filename,"r");
    while(fgets(pid, sizeof(pid), file)!=NULL)
    strtok(pid, "\n"); // Strip newline.
    strncat( pro, pid, 10 );
    strncat( pro, fd, 10 );
    strncat( dir, pro, 10);
    fclose(file);

    DIR *dp;
    struct dirent *ep;

    dp = opendir (pro);
    if (dp != NULL)
      {
        while ((ep = readdir (dp)) != NULL)
          memcpy(str, ep->d_name, 60);
          strncat( pro, &str, 60);
          printf("%s\n", pro);
        (void) closedir (dp);
      }
    else
      perror ("Couldn't open the directory");

}

int main(void)
{
    if (fopen("/var/run/apache2/apache2.pid", "r") != NULL) {
        char filename[] = "/var/run/apache2/apache2.pid";
        findpid(filename);
    }

    else if (fopen("/var/run/httpd/httpd.pid", "r") != NULL) {
        char filename[] = "/var/run/httpd/httpd.pid";
        findpid(filename);
    }
    else if (fopen("/var/run/nginx.pid", "r") != NULL) {
        char filename[] = "/var/run/nginx.pid";
        findpid(filename);
    }
    else {
        printf("Nothing found.\n");
    }

    return (0);
}