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From: "Suma Choudhary" <sumac@myw.ltindia.com>
To: glynn@gclements.plus.com
Cc: linux-c-programming@vger.kernel.org
Subject: Re: just curious!
Date: Mon, 10 Oct 2005 07:55:08 +0530	[thread overview]
Message-ID: <s34a1e7f.028@EMAIL> (raw)

Thanks a lot.....

I got to know about the utmp file and the terminal device from the strace and ltrace as suggested by David Eduardo.Could even write  a small code to emulate "write".

Didnt know about "mesg" though.

Thanks again
suma

>>> Glynn Clements <glynn@gclements.plus.com> 10/08/05 12:54 PM >>>

Suma Choudhary wrote:

> I was curious to know how the "write" command works.Any IPCs used?

It determines the terminal(s) on which the specified user is logged in
from the utmp file, opens the terminal device for writing, and writes
to it.

Note that the terminal device must be group-writeable (normally
controlled using "mesg y" or "mesg n"). The write command itself is
setgid tty.

-- 
Glynn Clements <glynn@gclements.plus.com>
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             reply	other threads:[~2005-10-10  2:25 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-10-10  2:25 Suma Choudhary [this message]
  -- strict thread matches above, loose matches on Subject: below --
2005-10-06 12:11 just curious! Suma Choudhary
2005-10-06 12:41 ` David Eduardo Gómez Noguera
2005-10-08  7:17 ` Glynn Clements

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