From owner-freebsd-questions@freebsd.org  Fri Oct 28 03:48:37 2016
Return-Path: <owner-freebsd-questions@freebsd.org>
Delivered-To: freebsd-questions@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 94260C21472
 for <freebsd-questions@mailman.ysv.freebsd.org>;
 Fri, 28 Oct 2016 03:48:37 +0000 (UTC)
 (envelope-from citrin+bsd@citrin.ru)
Received: from hz.citrin.ru (hz.citrin.ru [IPv6:2a01:4f8:d16:10c3::2])
 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 5B9FD684
 for <freebsd-questions@freebsd.org>; Fri, 28 Oct 2016 03:48:37 +0000 (UTC)
 (envelope-from citrin+bsd@citrin.ru)
Received: from x220.lan (c-24-60-168-172.hsd1.ct.comcast.net [24.60.168.172])
 by hz.citrin.ru (Postfix) with ESMTPSA id F085228A5C2
 for <freebsd-questions@freebsd.org>; Fri, 28 Oct 2016 03:48:31 +0000 (UTC)
Subject: Re: Interesting $0 Problem
To: freebsd-questions@freebsd.org
References: <b859f7a3-51d1-06f4-e793-332edd212068@tundraware.com>
 <20161028014923.GA11638@fedora24>
 <a6931603-c2b2-1dc7-6997-ae896db90d88@tundraware.com>
 <5812B617.5070701@gmail.com>
 <27078.128.135.52.6.1477621835.squirrel@cosmo.uchicago.edu>
 <20161028024041.GA93243@spectrum.skysmurf.nl>
 <2b1b598d-2ff1-2fa4-03d1-4771aa6f9c4d@tundraware.com>
From: Anton Yuzhaninov <citrin+bsd@citrin.ru>
Message-ID: <5b07633f-3241-27a5-15fc-1c138a3083d8@citrin.ru>
Date: Thu, 27 Oct 2016 23:48:29 -0400
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <2b1b598d-2ff1-2fa4-03d1-4771aa6f9c4d@tundraware.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrin.ru; s=s0;
 t=1477626512; bh=rZQJHlDe8xNLelZB4ZpQn8UeihxPX+hzHTwBDHobtRY=;
 h=Subject:To:References:From:Message-ID:Date:MIME-Version:In-Reply-To:Content-Type:Content-Transfer-Encoding;
 b=h6Jacq6fI1Zg1QaZDH9G5Xfm+PzCxrBp790MXE80tzrMdosPCXGTtnbMTAjihKdu1e9VpYAqK07D/W4itprDjx7BevPlBYbXT9ICZ7Kuacc8RKce1zYkwxoVSafQCH+DHdy5Ucthk0we40kIfZ7hUW9rFsWF8EQhzCnK1LrxraI=
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions/>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 28 Oct 2016 03:48:37 -0000

On 10/27/16 22:44, Tim Daneliuk wrote:
> I've used *BSD for decades and this is a new one to me.  I've never seen
> this behavior anywhere else (like Linux).  Do you have some sense of the
> rationale' for this?

It is very old Unix convention - argv[0] for login shells is prefixed by 
"-".

 From AT&T UNIX SRV2 (released in April, 1984):

file /src/cmd/login.c

char    minusnam[16] = "-";

...

/*      Generate the name of the shell with a '-' sign in front of it.  */
/*      This causes .profile processing when a shell is exec'ed.        */

         strcat(minusnam, namep);