env.c

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/*      env 1.1 - Set environment for command           Author: Kees J. Bot
 *                                                              17 Dec 1997
 */
#define nil 0
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

int main(int argc, char **argv)
{
        int i;
        int iflag= 0;
        int aflag= 0;
        extern char **environ;

        i= 1;
        while (i < argc && argv[i][0] == '-') {
                char *opt= argv[i++] + 1;

                if (opt[0] == '-' && opt[1] == 0) break;        /* -- */

                if (opt[0] == 0) iflag= 1;                      /* - */

                while (*opt != 0) switch (*opt++) {
                case 'i':
                        iflag= 1;       /* Clear environment. */
                        break;
                case 'a':               /* Specify arg 0 separately. */
                        aflag= 1;
                        break;
                default:
                        fprintf(stderr,
                "Usage: env [-ia] [name=value] ... [utility [argument ...]]\n");
                        exit(1);
                }
        }

        /* Clear the environment if -i. */
        if (iflag) *environ= nil;

        /* Set the new environment strings. */
        while (i < argc && strchr(argv[i], '=') != nil) {
                if (putenv(argv[i]) != 0) {
                        fprintf(stderr, "env: Setting '%s' failed: %s\n",
                                argv[i], strerror(errno));
                        exit(1);
                }
                i++;
        }

        /* Environment settings and command may be separated with '--'.
         * This is for compatibility with other envs, we don't advertise it.
         */
        if (i < argc && strcmp(argv[i], "--") == 0) i++;

        if (i >= argc) {
                /* No utility given; print environment. */
                char **ep;

                for (ep= environ; *ep != nil; ep++) {
                        if (puts(*ep) == EOF) {
                                fprintf(stderr, "env: %s\n", strerror(errno));
                                exit(1);
                        }
                }
                return 0;
        } else {
                char *util, **args;
                int err;

                util= argv[i];
                args= argv + i;
                if (aflag) args++;
                (void) execvp(util, args);
                err= errno;
                fprintf(stderr, "env: Can't execute %s: %s\n",
                        util, strerror(err));
                return err == ENOENT ? 127 : 126;
        }
}

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