Re: [PLUG] Why does -t option of ssh cause mail to not be sent?...

[Fred Stluka <fred@bristle.com>]

Conor,

> This command, however, would fail with "Error opening terminal: unknown.":
Right.  Similar to the reason I use ssh -t to run sudo commands.
It wants a terminal to prompt for password, if necessary.

> Try specifying a full path when calling your "junk" script. In 
> glancing over the manpage for SSH, I can't tell what environment those 
> pseudo-ttys inherit; I'd imagine the normal user environment, but try 
> anyway.
I'm not having any trouble finding the junk script.  It runs just fine.
The only problem is that the mail doesn't get sent unless there is
enough stuff after it in the script to give the mail time to be sent
before the script ends.  So, specifying the full path to the junk script
should not matter, right?


--Fred
------------------------------------------------------------------------
Fred Stluka -- mailto:fred@bristle.com -- http://bristle.com/~fred/
Bristle Software, Inc -- http://bristle.com -- Glad to be of service!
Open Source: Without walls and fences, we need no Windows or Gates.
------------------------------------------------------------------------

On 4/9/12 9:48 AM, Conor Schaefer wrote:
> In my experience, the -t option is useful when I want something to 
> enjoy a screen of its own, i.e. to remain running. Case in point: from 
> my laptop I can easily:
>
> ssh SERVERALIAS ls
>
> Then I'm right back at my local laptop prompt, which the output of 
> "ls" from my server's home directory printed above. This command, 
> however, would fail with "Error opening terminal: unknown.":
>
> ssh SERVERALIAS htop
>
> because htop requires a screen to display on.
>
> Try specifying a full path when calling your "junk" script. In 
> glancing over the manpage for SSH, I can't tell what environment those 
> pseudo-ttys inherit; I'd imagine the normal user environment, but try 
> anyway.
>
> On Mon, Apr 9, 2012 at 9:42 AM, Fred Stluka <fred@bristle.com 
> <mailto:fred@bristle.com>> wrote:
>
>     Linux gurus,
>
>     Any idea why the -t option of ssh causes mail to not be sent when I
>     use the command:
>
>        ssh -t mydomain.com <http://mydomain.com> ./junk
>
>     where ./junk contains:
>
>        #!/bin/csh -f
>        echo "hello" | mail -s "Test" fred
>
>     Works fine w/o the -t option.
>
>     The -t option causes ssh to allocate a "pseudo tty".  I don't know all
>     the ramifications of using a "pseudo tty", but -t is necessary when I
>     use ssh to execute a sudo command, so I tend to use it all the time.
>     For more info on that, see:
>     http://bristle.com/Tips/Unix.htm#sudo_via_ssh
>     http://bristle.com/Tips/Unix.htm#use_scripts_for_frequent_ssh_access_to_bash
>
>     In this case, it seems that the script ends before the e-mail gets
>     fully handed off to sendmail or something, and so the ssh session
>     terminates and the mail never gets sent.
>
>     Works fine if I do any of the following:
>     - Not use -t
>     - Add a sleep command to the end of the script, to slow it down, like:
>            sleep 1
>     - Use -v (verbose) option on mail to cause it to display details of
>       delivery to the terminal.
>
>     I've been doing a tail-f of the mail log.  When the mail doesn't
>     get send,
>     there are no log entries at all.
>
>     Any explanations?
>
>     --Fred
>     ------------------------------------------------------------------------
>     Fred Stluka -- mailto:fred@bristle.com <mailto:fred@bristle.com>
>     -- http://bristle.com/~fred/ <http://bristle.com/%7Efred/>
>     Bristle Software, Inc -- http://bristle.com -- Glad to be of service!
>     Open Source: Without walls and fences, we need no Windows or Gates.
>     ------------------------------------------------------------------------
>     ___________________________________________________________________________
>     Philadelphia Linux Users Group         -- http://www.phillylinux.org
>     Announcements -
>     http://lists.phillylinux.org/mailman/listinfo/plug-announce
>     General Discussion  --
>     http://lists.phillylinux.org/mailman/listinfo/plug
>
>
>
>
> ___________________________________________________________________________
> Philadelphia Linux Users Group         --        http://www.phillylinux.org
> Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
> General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug
___________________________________________________________________________
Philadelphia Linux Users Group         --        http://www.phillylinux.org
Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce
General Discussion  --   http://lists.phillylinux.org/mailman/listinfo/plug