src/env.c

   1 /* env - run a program in a modified environment
   2    Copyright (C) 1986, 1991-1999 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Richard Mlynarik and David MacKenzie */
  19
  20 /* Options:
  21    -
  22    -i
  23    --ignore-environment
  24         Construct a new environment from scratch; normally the
  25         environment is inherited from the parent process, except as
  26         modified by other options.
  27
  28    -u variable
  29    --unset=variable
  30         Unset variable VARIABLE (remove it from the environment).
  31         If VARIABLE was not set, does nothing.
  32
  33    variable=value (an arg containing a "=" character)
  34         Set the environment variable VARIABLE to value VALUE.  VALUE
  35         may be of zero length ("variable=").  Setting a variable to a
  36         zero-length value is different from unsetting it.
  37
  38    --
  39         Indicate that the following argument is the program
  40         to invoke.  This is necessary when the program's name
  41         begins with "-" or contains a "=".
  42
  43    The first remaining argument specifies a program to invoke;
  44    it is searched for according to the specification of the PATH
  45    environment variable.  Any arguments following that are
  46    passed as arguments to that program.
  47
  48    If no command name is specified following the environment
  49    specifications, the resulting environment is printed.
  50    This is like specifying a command name of "printenv".
  51
  52    Examples:
  53
  54    If the environment passed to "env" is
  55         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks }
  56
  57    env - foo
  58         runs "foo" in a null environment.
  59
  60    env foo
  61         runs "foo" in the environment
  62         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks }
  63
  64    env DISPLAY=gnu:0 nemacs
  65         runs "nemacs" in the envionment
  66         { LOGNAME=rms EDITOR=emacs PATH=.:/gnubin:/hacks DISPLAY=gnu:0 }
  67
  68    env - LOGNAME=foo /hacks/hack bar baz
  69         runs the "hack" program on arguments "bar" and "baz" in an
  70         environment in which the only variable is "LOGNAME".  Note that
  71         the "-" option clears out the PATH variable, so one should be
  72         careful to specify in which directory to find the program to
  73         call.
  74
  75    env -u EDITOR LOGNAME=foo PATH=/energy -- e=mc2 bar baz
  76         runs the program "/energy/e=mc2" with environment
  77         { LOGNAME=foo PATH=/energy }
  78 */
  79
  80 #include <config.h>
  81 #include <stdio.h>
  82 #include <getopt.h>
  83 #include <sys/types.h>
  84 #include <getopt.h>
  85
  86 #include "system.h"
  87 #include "error.h"
  88
  89 int putenv ();
  90
  91 extern char **environ;
  92
  93 /* The name by which this program was run. */
  94 char *program_name;
  95
  96 /* If nonzero, display usage information and exit.  */
  97 static int show_help;
  98
  99 /* If nonzero, print the version on standard output and exit.  */
 100 static int show_version;
 101
 102 static struct option const longopts[] =
 103 {
 104   {"help", no_argument, &show_help, 1},
 105   {"ignore-environment", no_argument, NULL, 'i'},
 106   {"unset", required_argument, NULL, 'u'},
 107   {"version", no_argument, &show_version, 1},
 108   {NULL, 0, NULL, 0}
 109 };
 110
 111 void
 112 usage (int status)
 113 {
 114   if (status != 0)
 115     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 116              program_name);
 117   else
 118     {
 119       printf (_("\
 120 Usage: %s [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n"),
 121               program_name);
 122       printf (_("\
 123 Set each NAME to VALUE in the environment and run COMMAND.\n\
 124 \n\
 125   -i, --ignore-environment   start with an empty environment\n\
 126   -u, --unset=NAME           remove variable from the environment\n\
 127       --help                 display this help and exit\n\
 128       --version              output version information and exit\n\
 129 \n\
 130 A mere - implies -i.  If no COMMAND, print the resulting environment.\n\
 131 "));
 132       puts (_("\nReport bugs to <bug-sh-utils@gnu.org>."));
 133     }
 134   exit (status);
 135 }
 136
 137 int
 138 main (register int argc, register char **argv, char **envp)
 139 {
 140   char *dummy_environ[1];
 141   int optc;
 142   int ignore_environment = 0;
 143
 144   program_name = argv[0];
 145   setlocale (LC_ALL, "");
 146   bindtextdomain (PACKAGE, LOCALEDIR);
 147   textdomain (PACKAGE);
 148
 149   while ((optc = getopt_long (argc, argv, "+iu:", longopts, NULL)) != -1)
 150     {
 151       switch (optc)
 152         {
 153         case 0:
 154           break;
 155         case 'i':
 156           ignore_environment = 1;
 157           break;
 158         case 'u':
 159           break;
 160         default:
 161           usage (2);
 162         }
 163     }
 164
 165   if (show_version)
 166     {
 167       printf ("env (%s) %s\n", GNU_PACKAGE, VERSION);
 168       exit (0);
 169     }
 170
 171   if (show_help)
 172     usage (0);
 173
 174   if (optind != argc && !strcmp (argv[optind], "-"))
 175     ignore_environment = 1;
 176
 177   environ = dummy_environ;
 178   environ[0] = NULL;
 179
 180   if (!ignore_environment)
 181     for (; *envp; envp++)
 182       putenv (*envp);
 183
 184   optind = 0;                   /* Force GNU getopt to re-initialize. */
 185   while ((optc = getopt_long (argc, argv, "+iu:", longopts, NULL)) != -1)
 186     if (optc == 'u')
 187       putenv (optarg);          /* Requires GNU putenv. */
 188
 189   if (optind != argc && !strcmp (argv[optind], "-"))
 190     ++optind;
 191
 192   while (optind < argc && strchr (argv[optind], '='))
 193     putenv (argv[optind++]);
 194
 195   /* If no program is specified, print the environment and exit. */
 196   if (optind == argc)
 197     {
 198       while (*environ)
 199         puts (*environ++);
 200       exit (0);
 201     }
 202
 203   execvp (argv[optind], &argv[optind]);
 204   error (errno == ENOENT ? 127 : 126, errno, "%s", argv[optind]);
 205 }