/bin/true is a script which just returns true so you can do something like - quora.com 
while true do something done
Originally it was a shell script which exit'd zero (which is 'true' in shell script world), basically:
#!/bin/sh exit 0
At some point in its sorry existence AT&T added a long copyright and other info (yes, they copyrighted 'exit 0'). Something like:
#!/sbin/sh # Tag 0x00000f00 # Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T # All Rights Reserved # THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T # The copyright notice above does not evidence any # actual or intended publication of such source code. #ident "@(#)true:true.sh 1.4" #ident "$Revision: 1.6 $" exit 0
Then someone noticed that an empty script exits 0 so you don't even need the 'exit 0'. The copyright stayed however, a file which was empty except for the copyright. So an empty file was now the property of AT&T, unpublished of course. Talk about much ado about nothing! Now (checking Linux) it seems to actually be a binary because I guess someone decided that runs faster. The source version from GNU coreutils 8.23 for true.c is 80 lines long and the binary is 125KB (27KB stripped):
/* Exit with a status code indicating success. Copyright (C) 1999-2014 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 <http://www.gnu.org/licenses/>. */ #include <config.h> #include <stdio.h> #include <sys/types.h> #include "system.h" /* Act like "true" by default; false.c overrides this. */ #ifndef EXIT_STATUS # define EXIT_STATUS EXIT_SUCCESS #endif #if EXIT_STATUS == EXIT_SUCCESS # define PROGRAM_NAME "true" #else # define PROGRAM_NAME "false" #endif #define AUTHORS proper_name ("Jim Meyering") void usage (int status) { printf (_("\ Usage: %s [ignored command line arguments]\n\ or: %s OPTION\n\ "), program_name, program_name); printf ("%s\n\n", _(EXIT_STATUS == EXIT_SUCCESS ? N_("Exit with a status code indicating success.") : N_("Exit with a status code indicating failure."))); fputs (HELP_OPTION_DESCRIPTION, stdout); fputs (VERSION_OPTION_DESCRIPTION, stdout); printf (USAGE_BUILTIN_WARNING, PROGRAM_NAME); emit_ancillary_info (); exit (status); } int main (int argc, char **argv) { /* Recognize --help or --version only if it's the only command-line argument. */ if (argc == 2) { initialize_main (&argc, &argv); set_program_name (argv[0]); setlocale (LC_ALL, ""); bindtextdomain (PACKAGE, LOCALEDIR); textdomain (PACKAGE); /* Note true(1) will return EXIT_FAILURE in the edge case where writes fail with GNU specific options. */ atexit (close_stdout); if (STREQ (argv[1], "--help")) usage (EXIT_STATUS); if (STREQ (argv[1], "--version")) version_etc (stdout, PROGRAM_NAME, PACKAGE_NAME, Version, AUTHORS, (char *) NULL); } exit (EXIT_STATUS); }