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 //config:config PRINTENV
  11 //config:       bool "printenv (1.6 kb)"
  12 //config:       default y
  13 //config:       help
  14 //config:       printenv is used to print all or part of environment.
  15
  16 //applet:IF_PRINTENV(APPLET_NOFORK(printenv, printenv, BB_DIR_BIN, BB_SUID_DROP, printenv))
  17
  18 //kbuild:lib-$(CONFIG_PRINTENV) += printenv.o
  19
  20 //usage:#define printenv_trivial_usage
  21 //usage:       "[VARIABLE]..."
  22 //usage:#define printenv_full_usage "\n\n"
  23 //usage:       "Print environment VARIABLEs.\n"
  24 //usage:       "If no VARIABLE specified, print all."
  25
  26 #include "libbb.h"
  27
  28 /* This is a NOFORK applet. Be very careful! */
  29
  30 int printenv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  31 int printenv_main(int argc UNUSED_PARAM, char **argv)
  32 {
  33         int exit_code = EXIT_SUCCESS;
  34
  35         /* no variables specified, show whole env */
  36         if (!argv[1]) {
  37                 char **e = environ;
  38
  39                 /* environ can be NULL! (for example, after clearenv())
  40                  * Check for that:
  41                  */
  42                 if (e)
  43                         while (*e)
  44                                 puts(*e++);
  45         } else {
  46                 /* search for specified variables and print them out if found */
  47                 char *arg, *env;
  48
  49                 while ((arg = *++argv) != NULL) {
  50                         env = getenv(arg);
  51                         if (env)
  52                                 puts(env);
  53                         else
  54                                 exit_code = EXIT_FAILURE;
  55                 }
  56         }
  57
  58         fflush_stdout_and_exit(exit_code);
  59 }