From owner-freebsd-questions  Mon May 24 15:40:33 1999
Delivered-To: freebsd-questions@freebsd.org
Received: from www.inx.de (www.inx.de [195.21.255.251])
	by hub.freebsd.org (Postfix) with ESMTP id B27FC14CF9
	for <freebsd-questions@freebsd.org>; Mon, 24 May 1999 15:40:22 -0700 (PDT)
	(envelope-from jnickelsen@acm.org)
Received: from n65-53.berlin.snafu.de ([194.42.65.53] helo=goting.jn.berlin.snafu.de)
	by www.inx.de with esmtp (Exim 2.12 #2)
	id 10m3ON-0001K8-00; Tue, 25 May 1999 00:40:20 +0200
Received: from ockholm.jn.berlin.snafu.de (ockholm.jn.berlin.snafu.de [10.0.0.3])
	by goting.jn.berlin.snafu.de (Postfix) with ESMTP
	id 8728117D; Tue, 25 May 1999 00:14:05 +0200 (CEST)
Date: Tue, 25 May 1999 00:14:14 +0200
From: Juergen Nickelsen <jnickelsen@acm.org>
To: "Alexey V.Vinogradov" <alexv@Sun.Farlep.Net>
Cc: freebsd-questions@FreeBSD.ORG
Subject: Re: about stty and TERM variable
Message-ID: <829909.3136580054@ockholm.jn.berlin.snafu.de>
In-Reply-To: <199905241116.OAA21115@Sun.Farlep.Net>
Originator-Info: login-id=nickel; server=goting.jn.berlin.snafu.de
X-Mailer: Mulberry Demo (MacOS) [1.4.2.1, s/n Evaluation]
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Sender: owner-freebsd-questions@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

--On Mon, 24. Mai 1999 14:16 +0300 "Alexey V.Vinogradov"
<alexv@Sun.Farlep.Net> wrote:

> who i can change TERM variable for stty?
> i do in sh shell scripts TERM=vt100; export TERM
> and have after run:
> tput: no terminal tipe specified and no TERM enviromental variable

If you set or unset an environment variable of a process (usually the
shell), the change will be inherited to the child processes, but not to
the parent. Changing environment variables in a shell script will thus
effect the shell script and the programs started by the script, but not
your login shell (which, I assume, has started the script).

To change an environment variable for your login shell (or any other
interactive shell), set it either by hand or in a script that is
sourced by this shell (without starting a subprocess), or in a shell
function or alias.

For instance, I have a shell function (I use bash) "path" to change the
PATH variable. It calls a perl script, which does things to PATH (show
the PATH, add or delete components, or even call a text editor on
PATH). The script then writes the new PATH setting to stdout, which is
evaluated by the shell function. This works, because a shell function
runs in the process context of the shell which called the function.

Oh well, I think this still sounds complicated. Let me summarize:

  - *Calling* a script (or any other program) to set an environment
    variable in your current shell does *not* work.

  - *Sourcing* a script (which is then executed by your current shell)
    works. ("." with sh, ksh, zsh, bash; "source" with csh, tcsh.)

  - Using a shell function or alias works.

E. g. to add a directory in front of the path you could use a shell
function like

    adpath () { [ "$1" != "" ] && PATH=$1:$PATH ; }

for sh, ksh, zsh, bash; or for csh and tcsh an alias like

    alias addpath 'set path = ( \!* $path )'

Greetings, Juergen.



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message