1 /* whoami -- print effective userid
2
3 Copyright (C) 1989-2023 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
26 #include "system.h"
27 #include "long-options.h"
28 #include "quote.h"
29
30 /* The official name of this program (e.g., no 'g' prefix). */
31 #define PROGRAM_NAME "whoami"
32
33 #define AUTHORS proper_name ("Richard Mlynarik")
34
35 void
usage(int status)36 usage (int status)
37 {
38 if (status != EXIT_SUCCESS)
39 emit_try_help ();
40 else
41 {
42 printf (_("Usage: %s [OPTION]...\n"), program_name);
43 fputs (_("\
44 Print the user name associated with the current effective user ID.\n\
45 Same as id -un.\n\
46 \n\
47 "), stdout);
48 fputs (HELP_OPTION_DESCRIPTION, stdout);
49 fputs (VERSION_OPTION_DESCRIPTION, stdout);
50 emit_ancillary_info (PROGRAM_NAME);
51 }
52 exit (status);
53 }
54
55 int
main(int argc,char ** argv)56 main (int argc, char **argv)
57 {
58 struct passwd *pw;
59 uid_t uid;
60 uid_t NO_UID = -1;
61
62 initialize_main (&argc, &argv);
63 set_program_name (argv[0]);
64 setlocale (LC_ALL, "");
65 bindtextdomain (PACKAGE, LOCALEDIR);
66 textdomain (PACKAGE);
67
68 atexit (close_stdout);
69
70 parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
71 Version, true, usage, AUTHORS,
72 (char const *) nullptr);
73
74 if (optind != argc)
75 {
76 error (0, 0, _("extra operand %s"), quote (argv[optind]));
77 usage (EXIT_FAILURE);
78 }
79
80 errno = 0;
81 uid = geteuid ();
82 pw = uid == NO_UID && errno ? nullptr : getpwuid (uid);
83 if (!pw)
84 error (EXIT_FAILURE, errno, _("cannot find name for user ID %lu"),
85 (unsigned long int) uid);
86 puts (pw->pw_name);
87 return EXIT_SUCCESS;
88 }
89