1 /* whoami -- print effective userid
2
3 Copyright (C) 1989-2018 Free Software Foundation, Inc.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 /* Equivalent to 'id -un'. */
19 /* Written by Richard Mlynarik. */
20
21 #include <config.h>
22 #include <stdio.h>
23 #include <sys/types.h>
24 #include <pwd.h>
25 #include <getopt.h>
26
27 #include "system.h"
28 #include "die.h"
29 #include "error.h"
30 #include "long-options.h"
31 #include "quote.h"
32
33 /* The official name of this program (e.g., no 'g' prefix). */
34 #define PROGRAM_NAME "whoami"
35
36 #define AUTHORS proper_name ("Richard Mlynarik")
37
38 static struct option const long_options[] =
39 {
40 {NULL, 0, NULL, 0}
41 };
42
43 void
usage(int status)44 usage (int status)
45 {
46 if (status != EXIT_SUCCESS)
47 emit_try_help ();
48 else
49 {
50 printf (_("Usage: %s [OPTION]...\n"), program_name);
51 fputs (_("\
52 Print the user name associated with the current effective user ID.\n\
53 Same as id -un.\n\
54 \n\
55 "), stdout);
56 fputs (HELP_OPTION_DESCRIPTION, stdout);
57 fputs (VERSION_OPTION_DESCRIPTION, stdout);
58 emit_ancillary_info (PROGRAM_NAME);
59 }
60 exit (status);
61 }
62
63 int
main(int argc,char ** argv)64 main (int argc, char **argv)
65 {
66 struct passwd *pw;
67 uid_t uid;
68 uid_t NO_UID = -1;
69
70 initialize_main (&argc, &argv);
71 set_program_name (argv[0]);
72 setlocale (LC_ALL, "");
73 bindtextdomain (PACKAGE, LOCALEDIR);
74 textdomain (PACKAGE);
75
76 atexit (close_stdout);
77
78 parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,
79 usage, AUTHORS, (char const *) NULL);
80 if (getopt_long (argc, argv, "", long_options, NULL) != -1)
81 usage (EXIT_FAILURE);
82
83 if (optind != argc)
84 {
85 error (0, 0, _("extra operand %s"), quote (argv[optind]));
86 usage (EXIT_FAILURE);
87 }
88
89 errno = 0;
90 uid = geteuid ();
91 pw = (uid == NO_UID && errno ? NULL : getpwuid (uid));
92 if (!pw)
93 die (EXIT_FAILURE, errno, _("cannot find name for user ID %lu"),
94 (unsigned long int) uid);
95 puts (pw->pw_name);
96 return EXIT_SUCCESS;
97 }
98