setenv MY_BASELINE `ps -ef | grep BASELINE | grep -v grep | tail -1 '
seems to work correctly
but
ps -ef | grep BASELINE | grep -v grep | tail -1 | xargs setenv
MY_BASELINE
doesn't work

can someone tell me what's wrong
thanks

JoshforRefugee <ankitks@yahoo.com> writes:

> setenv MY_BASELINE `ps -ef | grep BASELINE | grep -v grep | tail -1 '
> seems to work correctly

because your current shell executes it

> but
> ps -ef | grep BASELINE | grep -v grep | tail -1 | xargs setenv
> MY_BASELINE
> doesn't work

Because you are launching a new shell, and change the envoenment in
that new shell, which executes.

On Tue, 04 Sep 2007 15:44:16 -0700, JoshforRefugee wrote:

> setenv MY_BASELINE `ps -ef | grep BASELINE | grep -v grep | tail -1 '
> seems to work correctly
> but
> ps -ef | grep BASELINE | grep -v grep | tail -1 | xargs setenv
> MY_BASELINE
> doesn't work
>
> can someone tell me what's wrong
> thanks

There are at least two possible explanations, it would have ed if you
had shown us the output.

Reason number 1. You don't have a "setenv" program. Normally setenv is a
builtin for csh and tcsh.

Reason number 2. You are setting the environment variable, but it is in
an environment that is destroyed straight away. Your second syntax will
create a number of processes, at least 5, and maybe more. Each of these
processes will have a copy of the current environment, which they can
choose to alter. In particular the process running the "xargs" program
will have a copy. It will then typically create a new process to run the
"setenv" command, and this will have a copy of the environment from its
parent (the "xargs process"). The "setenv process" will alter its
environemnt, then exit, and that environment will be destroyed, The
original environment will be left unchanged. In contrast your first
syntax will create a number of processes, and the output of this will be
given to the setenv command *in the current shell*. As this is a builtin
command this will alter the environment of the current shell.

This question is essentially the same question as "why can't I write a
shell script that changes my current directory?".

>
> This question is essentially the same question as "why can't I write a
> shell script that changes my current directory?".

I am fairly new to unix env. Can you tell me why I can't write shell
script that changes my current dir

JoshforRefugee wrote:
>>This question is essentially the same question as "why can't I write a
>>shell script that changes my current directory?".
>
>
> I am fairly new to unix env. Can you tell me why I can't write shell
> script that changes my current dir
>

Because, unless you use ". script", that shell script will execute in a
sub-shell so you'll be changing directory only within that sub-shell.
See question 22 in the FAQ:

http://cfaj.freeshell.org/shell/cus-faq-2.html#22

for more info.

Ed

"JoshforRefugee" <ankitks@yahoo.com> schrieb im Newsbeitrag
news:1189091832.344264.267980@r34g2000hsd.googlegr oups.com...
>
>>
>> This question is essentially the same question as "why can't I write a
>> shell script that changes my current directory?".
>
> I am fairly new to unix env. Can you tell me why I can't write shell
> script that changes my current dir
Because that shell script would run in a new shell (child process of your
current one), change directory there, but then that new shell ends and in
your old shell you're still in the old directory.

Unless you explicitly tell your current shell interpret that script itself,
e.g. by using the . command.

Bye, Jojo

JoshforRefugee <ankitks@yahoo.com> writes:


> I am fairly new to unix env. Can you tell me why I can't write shell
> script that changes my current dir

Let me add this - what happens when you launch several new shells, and
change the environment to be different in each one?

Is the parent of these shells suppose to change? To which environment exactly?