Talk:Shell - Revision history

Ninereasons: /* What is a login shell? */ edit

2006-06-09T19:24:47Z

What is a login shell?: edit

Ninereasons: strikeout

2006-06-09T19:23:35Z

strikeout

Ninereasons: /* What is a login shell? */

2006-06-09T06:53:08Z

What is a login shell?

Ninereasons: /* What is a login shell? */

2006-06-09T06:48:27Z

What is a login shell?

Ninereasons: /* What is a login shell? */

2006-06-07T22:08:55Z

What is a login shell?

Ninereasons at 22:03, 7 June 2006

2006-06-07T22:03:55Z

Ninereasons: only root

2006-06-07T18:22:02Z

only root

Ninereasons: /* What is a login shell? */

2006-06-07T17:07:18Z

What is a login shell?

New page

==What is a login shell?==
I was a Slackware user for some time, before finding FreeBSD. One of the things that surprised me was that FreeBSD seems to be very fuzzy about what a login shell is. Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>). If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database. As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database. In fact, any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH.

%grep python /etc/passwd
pylogin:*:2011:2011:Login to python:/home/pylogin:/usr/local/bin/python

I don't know what might be the full implications; but it is somewhat surprising that it's possible to have a ssh session that looks like this:
<pre>
Using username "pylogin".
Using keyboard-interactive authentication.
Password:
Last login: Wed Jun 7 09:37:40 2006 from kanga
Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
The Regents of the University of California. All rights reserved.

FreeBSD 6.1-STABLE (GENERIC) #10: Mon Jun 5 09:57:27 PDT 2006

Welcome to FreeBSD AMD64!

Python 2.4.3 (#2, Apr 6 2006, 15:45:31)
[GCC 3.4.4 [FreeBSD] 20050518] on freebsd6
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> keys = os.environ.keys()
>>> for val in keys:
... print val,": ",os.environ[val]
...
TERM : xterm
SHELL : /usr/local/bin/python
MAIL : /var/mail/pylogin
BLOCKSIZE : K
FTP_PASSIVE_MODE : YES
SSH_TTY : /dev/ttyp5
SSH_CLIENT : 192.168.1.3 3173 22
LOGNAME : pylogin
USER : pylogin
HOME : /home/pylogin
PATH : /sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/sbin:/usr/local/bin:/usr/X11R6/bin:/home/pylogin/bin
SSH_CONNECTION : 192.168.1.3 3173 192.168.1.5 22
>>> ^d

</pre>

Useless, but interesting, eh? Here, the user's login shell is <code>/usr/local/bin/python</code>. Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database? — [[User:Ninereasons|Ninereasons]] 13:07, 7 June 2006 (EDT)

@@ Line 1: / Line 1: @@
 ==What is a login shell?==
-I was a Slackware user for some time, before finding FreeBSD.  <s>One of the things that surprised me was that FreeBSD seems to be fuzzier about what a login shell is.</s>  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  <s>If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.</s>  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
+I was a Slackware user for some time, before finding FreeBSD.  <s>One of the things that surprised me was that FreeBSD seems to be fuzzier about what a login shell is.</s>  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  If you attempt to change shells as an ordinary user, to provide a different login shell, it must exist in the shell database.  <s>As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.</s>  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
   %grep python /etc/passwd

@@ Line 1: / Line 1: @@
 ==What is a login shell?==
-I was a Slackware user for some time, before finding FreeBSD.  One of the things that surprised me was that <s>FreeBSD seems to be fuzzier about what a login shell is.</s>  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  <s>If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.</s>  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
+I was a Slackware user for some time, before finding FreeBSD.  <s>One of the things that surprised me was that FreeBSD seems to be fuzzier about what a login shell is.</s>  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  <s>If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.</s>  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
   %grep python /etc/passwd

@@ Line 1: / Line 1: @@
 ==What is a login shell?==
-I was a Slackware user for some time, before finding FreeBSD.  One of the things that surprised me was that FreeBSD seems to be fuzzier about what a login shell is.  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
+I was a Slackware user for some time, before finding FreeBSD.  One of the things that surprised me was that <s>FreeBSD seems to be fuzzier about what a login shell is.</s>  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  <s>If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.</s>  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
   %grep python /etc/passwd

← Older revision		Revision as of 06:48, 9 June 2006
Line 43:		Line 43:

	Useless, but interesting, eh? Here, the user's login shell is <code>/usr/local/bin/python</code>. Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database, if logged in as root? Maybe Linux works the same, but I just never noticed? — [[User:Ninereasons\|Ninereasons]] 13:07, 7 June 2006 (EDT)		Useless, but interesting, eh? Here, the user's login shell is <code>/usr/local/bin/python</code>. Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database, if logged in as root? Maybe Linux works the same, but I just never noticed? — [[User:Ninereasons\|Ninereasons]] 13:07, 7 June 2006 (EDT)
		+
		+	: It's true. I never noticed. Linux works just like this also. So, lftp, or cpan or the like, could be my login shell. Weird. [[User:Ninereasons\|Ninereasons]] 02:48, 9 June 2006 (EDT)

← Older revision		Revision as of 22:08, 7 June 2006
Line 42:		Line 42:
	</pre>		</pre>

−	Useless, but interesting, eh? Here, the user's login shell is <code>/usr/local/bin/python</code>. Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database, if logged in as root? — [[User:Ninereasons\|Ninereasons]] 13:07, 7 June 2006 (EDT)	+	Useless, but interesting, eh? Here, the user's login shell is <code>/usr/local/bin/python</code>. Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database, if logged in as root? Maybe Linux works the same, but I just never noticed? — [[User:Ninereasons\|Ninereasons]] 13:07, 7 June 2006 (EDT)

@@ Line 1: / Line 1: @@
 ==What is a login shell?==
-I was a Slackware user for some time, before finding FreeBSD.  One of the things that surprised me was that FreeBSD seems to be very fuzzy about what a login shell is.  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.  In fact, any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH.
+I was a Slackware user for some time, before finding FreeBSD.  One of the things that surprised me was that FreeBSD seems to be very fuzzy about what a login shell is.  Slackware, and I suppose any linux, has a shell database (<code>/etc/shells</code>).  If you attempt to assign a shell to a user, to provide their login shell, it must exist in the shell database.  As far as I can tell, there is no such restriction in FreeBSD even though it also has a shell database.  In fact, (as <code>root</code>) any program at all can be substituted for a shell in the Shell field of the user's login profile (<code>/etc/passwd</code>), as long as it exists in the global PATH (only root can specify non-standard shells - such as <code>/usr/sbin/nologin</code>).
   %grep python /etc/passwd
@@ Line 42: / Line 42: @@
 </pre>
-Useless, but interesting, eh?  Here, the user's login shell is <code>/usr/local/bin/python</code>.  Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database?  &mdash; [[User:Ninereasons|Ninereasons]] 13:07, 7 June 2006 (EDT)
+Useless, but interesting, eh?  Here, the user's login shell is <code>/usr/local/bin/python</code>.  Needless to say, that file is not listed in <code>/etc/shells</code>. When does FreeBSD use the shell database, if logged in as root?  &mdash; [[User:Ninereasons|Ninereasons]] 13:07, 7 June 2006 (EDT)