123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148 | /* GNU's users. Copyright (C) 1992-2025 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>. *//* Written by jla; revised by djm */#include <config.h>#include <stdio.h>#include <sys/types.h>#include"system.h"#include"long-options.h"#include"quote.h"#include"readutmp.h"/* The official name of this program (e.g., no 'g' prefix). */#define PROGRAM_NAME"users"#define AUTHORS \ proper_name ("Joseph Arceneaux"), \ proper_name ("David MacKenzie")static intuserid_compare(const void*v_a,const void*v_b){char**a = (char**) v_a;char**b = (char**) v_b;returnstrcmp(*a, *b);}static voidlist_entries_users(idx_t n,struct gl_utmp const*this){char**u =xinmalloc(n,sizeof*u); idx_t i; idx_t n_entries =0;while(n--){if(IS_USER_PROCESS(this)){char*trimmed_name; trimmed_name =extract_trimmed_name(this); u[n_entries] = trimmed_name;++n_entries;}this++;}qsort(u, n_entries,sizeof(u[0]), userid_compare);for(i =0; i < n_entries; i++){char c = (i < n_entries -1?' ':'\n');fputs(u[i], stdout);putchar(c);}for(i =0; i < n_entries; i++)free(u[i]);free(u);}/* Display a list of users on the system, according to utmp file FILENAME. Use read_utmp OPTIONS to read FILENAME. */static voidusers(char const*filename,int options){ idx_t n_users;struct gl_utmp *utmp_buf; options |= READ_UTMP_USER_PROCESS;if(read_utmp(filename, &n_users, &utmp_buf, options) !=0)error(EXIT_FAILURE, errno,"%s",quotef(filename));list_entries_users(n_users, utmp_buf);free(utmp_buf);}voidusage(int status){if(status != EXIT_SUCCESS)emit_try_help();else{printf(_("Usage: %s [OPTION]... [FILE]\n"), program_name);printf(_("\Output who is currently logged in according to FILE.\n\If FILE is not specified, use %s. %s as FILE is common.\n\\n\"), UTMP_FILE, WTMP_FILE);fputs(HELP_OPTION_DESCRIPTION, stdout);fputs(VERSION_OPTION_DESCRIPTION, stdout);emit_ancillary_info(PROGRAM_NAME);}exit(status);}intmain(int argc,char**argv){initialize_main(&argc, &argv);set_program_name(argv[0]);setlocale(LC_ALL,"");bindtextdomain(PACKAGE, LOCALEDIR);textdomain(PACKAGE);atexit(close_stdout);parse_gnu_standard_options_only(argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,true, usage, AUTHORS,(char const*)nullptr);switch(argc - optind){case0:/* users */users(UTMP_FILE, READ_UTMP_CHECK_PIDS);break;case1:/* users <utmp file> */users(argv[optind],0);break;default:/* lose */error(0,0,_("extra operand %s"),quote(argv[optind +1]));usage(EXIT_FAILURE);}return EXIT_SUCCESS;}
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