HOW TO distiguish between command input and forked subshell ?

HOW TO distiguish between command input and forked subshell ?

[C. v. Stuckrad]

Hi! (again :-)

I have another very spcific question...

I would like to have a zsh-function behave different if called
inside $(...) or backticks !
Exactly, I want to have the function 'chpwd' give some output
if triggered by 'cd' or 'chdir' BUT TO GIVE NO OUTPUT
if triggered by cases like  '... $(cd somewhere; ls)...' 

Might that be possible ?

Clueless (again),  Stucki

Christoph von Stuckrad       * *  | talk to  | <stucki@math.fu-berlin.de> \
Freie Universitaet Berlin    |/_* | nickname | ...!unido!fub!leibniz!stucki|
Fachbereich Mathematik, EDV  |\ * | 'stucki' | Tel:+49 30 838-7545{9|8}    |
Arnimallee 2-6/14195 Berlin  * *  |  on IRC  | Fax:+49 30 838-5913        /

Re: HOW TO distiguish between command input and forked subshell ?

[Bart Schaefer]

On Sep 6, 12:47am, C. v. Stuckrad wrote:
> Subject: HOW TO distiguish between command input and forked subshell ?
> 
> Hi! (again :-)

You should be asking these questions on zsh-users rather than zsh-workers.
They don't have much to do with zsh development or build problems.

Not that it would matter much, since everybody on zsh-workers also gets
zsh-users, but some people might be filtering based on the To: address.

> Exactly, I want to have the function 'chpwd' give some output
> if triggered by 'cd' or 'chdir' BUT TO GIVE NO OUTPUT
> if triggered by cases like  '... $(cd somewhere; ls)...' 
> 
> Might that be possible ?

chpwd() {
    if [[ -t 1 ]]
    then
	print By golly, my standard output is a terminal.
    fi
}

Re: HOW TO distiguish between command input and forked subshell ?

[Andrej Borsenkow]

On Thu, 5 Sep 1996, Bart Schaefer wrote:

> 
> > Exactly, I want to have the function 'chpwd' give some output
> > if triggered by 'cd' or 'chdir' BUT TO GIVE NO OUTPUT
> > if triggered by cases like  '... $(cd somewhere; ls)...' 
> > 
> > Might that be possible ?
> 
> chpwd() {
>     if [[ -t 1 ]]
>     then
> 	print By golly, my standard output is a terminal.
>     fi
> }
> 

There is a little problem with output of chdir(). Here follows:

if I cd to non-local directory using CDPATH, cd will report current
directory after changing to it. I always found it boring (as I have
directory in prompt anyway) and suggested the option to shut it off. The
answer was (as expected ;) that I can use

cd () { builtin cd $* > /dev/null }

Well, it works, but any output from chdir() is also lost :( I don't
know, if it is right, that chdir() is using the same descriptor as cd, but
if it is to be so, may be new option is still useful? 

greetings

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Andrej Borsenkow 		Fax:   +7 (095) 252 01 05
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Re: HOW TO distiguish between command input and forked subshell ?

[Zoltan Hidvegi]

> if I cd to non-local directory using CDPATH, cd will report current
> directory after changing to it. I always found it boring (as I have
> directory in prompt anyway) and suggested the option to shut it off. The
> answer was (as expected ;) that I can use
> 
> cd () { builtin cd $* > /dev/null }
> 
> Well, it works, but any output from chdir() is also lost :( I don't
> know, if it is right, that chdir() is using the same descriptor as cd, but
> if it is to be so, may be new option is still useful? 

I assume that chdir above was really ment to be chpwd.  Chpwd output is not
lost if it is redirected to stderr.

Zoltan