which.c

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/* which - search paths for executable */

#define DELIMITER ':'

#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>

_PROTOTYPE(int main, (int argc, char **argv));

int main(ac, av)
int ac;
char **av;
{
  char *path, *cp;
  char buf[400];
  char prog[400];
  char patbuf[512];
  int quit, none;
  int excode = 0;

  if (ac < 2) {
        fprintf(stderr, "Usage: %s cmd [cmd, ..]\n", *av);
        exit(1);
  }
  av[ac] = 0;
  for (av++; *av; av++) {

        quit = 0;
        none = 1;
        if ((path = getenv("PATH")) == NULL) {
                fprintf(stderr, "Null path.\n");
                exit(0);
        }
        strcpy(patbuf, path);
        path = patbuf;
        cp = path;

        while (1) {
                cp = strchr(path, DELIMITER);
                if (cp == NULL)
                        quit++;
                else
                        *cp = '\0';

                if (strcmp(path, "") == 0 && quit == 0) {
                        sprintf(buf, "%s./%s", path, *av);
                } else
                        sprintf(buf, "%s/%s", path, *av);

                /* Fprintf(stderr,"Trying %s, path %s\n",buf,path); */

                path = ++cp;

                if (access(buf, 1) == 0) {
                        printf("%s\n", buf);
                        none = 0;
                }
                sprintf(prog, "%s.%s", buf, "prg");
                if (access(prog, 1) == 0) {
                        printf("%s\n", prog);
                        none = 0;
                }
                sprintf(prog, "%s.%s", buf, "ttp");
                if (access(prog, 1) == 0) {
                        printf("%s\n", prog);
                        none = 0;
                }
                sprintf(prog, "%s.%s", buf, "tos");
                if (access(prog, 1) == 0) {
                        printf("%s\n", prog);
                        none = 0;
                }
                if (quit) {
                        if (none) {
                                fprintf(stderr, "No %s in %s\n", *av, getenv("PATH"));
                                excode = 1;
                        }
                        break;
                }
        }
  }
  return(excode);
}

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