tee-like file redirection in shell?

tee-like file redirection in shell?

[Sweth Chandramouli]

	is there currently some way to reproduce the effect of
the tee command in the shell itself, and if not, what do people
think of the idea of adding that ability (either by new file
redirectors or by making tee a builtin)?  a couple of times
recently, i've been caused many problems by the fact that tee
is a standalone program, and as such doesn't care about the
value of options like clobber; since tee _is_ basically just
another form of file redirection, it would be nice to have it's
behaviour be consistent with the other forms provided by the
shell.

	-- sweth.

-- 
Sweth Chandramouli
IS Coordinator, The George Washington University
<sweth@gwu.edu> / (202) 994 - 8521 (V) / (202) 994 - 0458 (F)
<a href="http://astaroth.nit.gwu.edu/~sweth/disc.html">*</a>

Re: tee-like file redirection in shell?

[Geoff Wing]

Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> typed:
:	is there currently some way to reproduce the effect of
:the tee command in the shell itself, and if not, what do people
:think of the idea of adding that ability (either by new file
:redirectors or by making tee a builtin)?  a couple of times
:recently, i've been caused many problems by the fact that tee
:is a standalone program, and as such doesn't care about the
:value of options like clobber; since tee _is_ basically just
:another form of file redirection, it would be nice to have it's
:behaviour be consistent with the other forms provided by the
:shell.

You need to have the appropriate setopt.  See MULTIOS in the manual. 

Regards,
-- 
Geoff Wing   <gcw@pobox.com>            Mobile : (Australia) 0413 431 874
Work URL: http://www.primenet.com.au/   Ego URL: http://pobox.com/~gcw/

Re: tee-like file redirection in shell?

[Bruce Stephens]

Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> writes:

> 	is there currently some way to reproduce the effect of
> the tee command in the shell itself,

Yes.  This works for me:

        % ps > some_file | cat

You need the multios option set, and I don't recall whether it's the
default or not (it probably should be).

Is there any nicer way to say "save to a file and show the results"
than using the ugly "| cat"?

Re: tee-like file redirection in shell?

[Sweth Chandramouli]

On Wed, Jun 09, 1999 at 08:16:39PM +0100, Bruce Stephens wrote:
> Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> writes:
> 
> > 	is there currently some way to reproduce the effect of
> > the tee command in the shell itself,
> 
> Yes.  This works for me:
> 
>         % ps > some_file | cat
> 
> You need the multios option set, and I don't recall whether it's the
> default or not (it probably should be).
	it's not set by default, but this does do exactly what i want.

> Is there any nicer way to say "save to a file and show the results"
> than using the ugly "| cat"?

	i don't know that it's particularly nicer, but something like
% ps > some_file > /dev/stdout
	should at least save a process from being spawned.

	-- sweth.

-- 
Sweth Chandramouli
IS Coordinator, The George Washington University
<sweth@gwu.edu> / (202) 994 - 8521 (V) / (202) 994 - 0458 (F)
<a href="http://astaroth.nit.gwu.edu/~sweth/disc.html">*</a>

Re: tee-like file redirection in shell?

[Geoff Wing]

Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> typed:
:On Wed, Jun 09, 1999 at 08:16:39PM +0100, Bruce Stephens wrote:
:> Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> writes:
:> > 	is there currently some way to reproduce the effect of
:> > the tee command in the shell itself,
:> Yes.  This works for me:
:>         % ps > some_file | cat
:> Is there any nicer way to say "save to a file and show the results"
:> than using the ugly "| cat"?
:	i don't know that it's particularly nicer, but something like
:% ps > some_file > /dev/stdout
:	should at least save a process from being spawned.

% ps >&1 >some_file

NB: take care with the order, it's not
% ps >some_file >&1

Regards,
-- 
Geoff Wing   <gcw@pobox.com>            Mobile : (Australia) 0413 431 874
Work URL: http://www.primenet.com.au/   Ego URL: http://pobox.com/~gcw/

Re: tee-like file redirection in shell?

[Bart Schaefer]

On Jun 9,  5:29pm, Sweth Chandramouli wrote:
} Subject: Re: tee-like file redirection in shell?
}
} On Wed, Jun 09, 1999 at 08:16:39PM +0100, Bruce Stephens wrote:
} > Sweth Chandramouli <sweth@astaroth.nit.gwu.edu> writes:
} > 
} > You need the multios option set, and I don't recall whether it's the
} > default or not (it probably should be).

It's not set by default because of the way it interacts with globbing.
If you do something like

	echo "Create this file" > *

then zsh will write to every file in the current directory (unless the
noclobber option is set).

} > Is there any nicer way to say "save to a file and show the results"
} > than using the ugly "| cat"?
} 
} 	i don't know that it's particularly nicer, but something like
} % ps > some_file > /dev/stdout

In addition to the trick that Geoff mentioned using >&1, zsh interprets
the path /dev/fd/ magically.  So on any operating system, even those that
do not support the /dev/fd/ directory, you can use

	/dev/fd/0	(standard input)
	/dev/fd/1	(standard output)
	/dev/fd/2	(standard error)
	(etc.)

So >/dev/fd/1 is the same as >&1, and so forth, except that with the
/dev/fd/ files the file descriptor must already exist -- it won't be
duplicated from another file descriptor.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com