coreutils/printenv.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * printenv implementation for busybox
   4  *
   5  * Copyright (C) 2005 by Erik Andersen <andersen@codepoet.org>
   6  * Copyright (C) 2005 by Mike Frysinger <vapier@gentoo.org>
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   9  */
  10
  11 //usage:#define printenv_trivial_usage
  12 //usage:       "[VARIABLE]..."
  13 //usage:#define printenv_full_usage "\n\n"
  14 //usage:       "Print environment VARIABLEs.\n"
  15 //usage:       "If no VARIABLE specified, print all."
  16
  17 #include "libbb.h"
  18
  19 /* This is a NOFORK applet. Be very careful! */
  20
  21 int printenv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  22 int printenv_main(int argc UNUSED_PARAM, char **argv)
  23 {
  24         int exit_code = EXIT_SUCCESS;
  25
  26         /* no variables specified, show whole env */
  27         if (!argv[1]) {
  28                 char **e = environ;
  29
  30                 /* environ can be NULL! (for example, after clearenv())
  31                  * Check for that:
  32                  */
  33                 if (e)
  34                         while (*e)
  35                                 puts(*e++);
  36         } else {
  37                 /* search for specified variables and print them out if found */
  38                 char *arg, *env;
  39
  40                 while ((arg = *++argv) != NULL) {
  41                         env = getenv(arg);
  42                         if (env)
  43                                 puts(env);
  44                         else
  45                                 exit_code = EXIT_FAILURE;
  46                 }
  47         }
  48
  49         fflush_stdout_and_exit(exit_code);
  50 }