2 more questions

2 more questions

[Uli Zappe]

Hi,

sorry I have to bother you yet again, but I have two more problems  
left that I couldn't solve with the zsh documentation:

1. Is there a way in zsh to pass the standard output to a parameter 
   instead of the standard input of a command? I.e. I have

      command1 | command2 parameter

   and need the output of command1 as the parameter for command2

2. How do I pipe the elements of an array into a command? If I do a

      echo $ARRAY | command

   the elements are separated only by whitespace instead of newlines 
   which will not work correctly especially if the elements possibly
   contain whitespace themselves. It works, of course, with a for-do
   loop but that's not efficient enough.

Thank you very much for every hint!


                Bye
                        Uli

______________________________________________________________________

Uli Zappe               E-Mail: uli@tallowcross.uni-frankfurt.de
                                (NeXTMail,Mime,ASCII) PGP on request
Lorscher Strasse 5      WWW:    -
D-60489 Frankfurt       Fon:    +49 (69) 9784 0007
Germany                 Fax:    +49 (69) 9784 0042

staff member of NEXTTOYOU - the German NEXTSTEP/OPENSTEP magazine
______________________________________________________________________

Re: 2 more questions

[Tomas Gradin]

>1. Is there a way in zsh to pass the standard output to a parameter 
>   instead of the standard input of a command? I.e. I have
>
>      command1 | command2 parameter
>
>   and need the output of command1 as the parameter for command2

command2 =(command1)

>2. How do I pipe the elements of an array into a command? If I do a
>
>      echo $ARRAY | command
>
>   the elements are separated only by whitespace instead of newlines 
>   which will not work correctly especially if the elements possibly
>   contain whitespace themselves. It works, of course, with a for-do
>   loop but that's not efficient enough.

echo $ARRAY | xargs -n 1 command

/tg

Re: 2 more questions

[Duncan Sargeant]

uli (Uli Zappe) scandalously alleged:                          (on Feb 21, 1997)
> Hi,
> 
> sorry I have to bother you yet again, but I have two more problems  
> left that I couldn't solve with the zsh documentation:
> 
> 1. Is there a way in zsh to pass the standard output to a parameter 
>    instead of the standard input of a command? I.e. I have
> 
>       command1 | command2 parameter
>
>    and need the output of command1 as the parameter for command2

command2 `command1`

I can see how you were probably looking in the wrong place :)

> 
> 2. How do I pipe the elements of an array into a command? If I do a
> 
>       echo $ARRAY | command
> 
>    the elements are separated only by whitespace instead of newlines 
>    which will not work correctly especially if the elements possibly
>    contain whitespace themselves. It works, of course, with a for-do
>    loop but that's not efficient enough.

echo ${(j:\n:)ARRAY} | command

umm, there may be a way to pipe the variable to stdin of command
without the use of echo ... I'd be interested to know what it is.

again you were probably looking in the wrong places for this answer
:)

I learnt these tricks and a whole lot more, or at least worked out
where to look for info in the man pages when I did a 
man -T ps zshall > zshdocs.ps (I think? from memory, anyway), to
create the man page as a postscript file, which I then printed, and
read like a book, making notes on all those cool features.  Its a
great way to more fully appreciate zsh, if you can afford the
paper.

,dunc

-- 
Duncan Sargeant, keraunothnetophobic.   WWW: http://www.ucc.gu.uwa.edu.au/~dunc/
Orr would be crazy to fly more missions and sane if he didnt, but if he was sane
he had to fly them.  If he flew then he was crazy and didn't have to; but if he
didn't want to he was sane and had to.  Yossarian was moved deeply and let out a
respectful whistle at the absolute simplicity of this clause of Catch-22. --jh

Re: 2 more questions

[Zefram]

Uli Zappe wrote:
>1. Is there a way in zsh to pass the standard output to a parameter 
>   instead of the standard input of a command? I.e. I have
>
>      command1 | command2 parameter
>
>   and need the output of command1 as the parameter for command2

command2 "$(command1)"

>2. How do I pipe the elements of an array into a command? If I do a
>
>      echo $ARRAY | command
>
>   the elements are separated only by whitespace instead of newlines 
>   which will not work correctly especially if the elements possibly
>   contain whitespace themselves.

print -l "$ARRAY[@]" | command

but in the case of zero elements this will provide a single newline,
and it will produce ambiguous output if the array elements can contain
newlines.

command "$ARRAY[@]"

is the best interface, if it is feasible.

-zefram

Re: 2 more questions

[Uli Zappe]

Hi,

first, a LOT of thanks to you all for all of your answers! :-))

My second problem was easily solved by print -l which fits my needs  
perfectly. It's the same as echo "$VARIABLE" in sh (the quotes make  
for a newline there) which doesn't work in zsh.


The first, however, proved more tricky, mainly because I failed to  
make clear that I'd really need the stdout of the foregoing process  
in a VARIABLE, because I need it TWO times in the command  
afterwards.

Actually, my task was the following:

    cat $FILE | mv $FIELD1_IN_LINEX_OF_FILE $FIELD2_IN_LINEX_OF_FILE

I thought I had read of such a variable in zsh somewhere and just  
couldn't find it anymore, but judging by your comments I was simply  
mistaken.

What I tried then was a

      $(cat $FILE | awk '{printf("mv %s %s\n",$1,$2)}')

This works perfectly with only one line in $FILE, but I couldn't  
get it to work with more than one. Obviously the shell interprets  
the WHOLE output of &(...) as always ONE SINGLE command no matter  
what I do.

So I ended up with

      IFS="
      "
      LINES=($(cat $FILE))
      IFS=$DEFAULT_IFS
      for LINE in $LINES
      do
      $(echo $LINE | awk '{printf("mv %s %s\n",$1,$2)}')
      done

which is the best solution I was able to find.

Thanks again!


                Bye
                        Uli

______________________________________________________________________

Uli Zappe               E-Mail: uli@tallowcross.uni-frankfurt.de
                                (NeXTMail,Mime,ASCII) PGP on request
Lorscher Strasse 5      WWW:    -
D-60489 Frankfurt       Fon:    +49 (69) 9784 0007
Germany                 Fax:    +49 (69) 9784 0042

staff member of NEXTTOYOU - the German NEXTSTEP/OPENSTEP magazine
______________________________________________________________________

Re: 2 more questions

[Tomas Gradin]

>Actually, my task was the following:
>
>    cat $FILE | mv $FIELD1_IN_LINEX_OF_FILE $FIELD2_IN_LINEX_OF_FILE

Ah, I see. I would do it like this:

cat $FILE | awk '{print $1,$2}' | xargs -n 2 mv

/tg

Re: 2 more questions

[Uli Zappe]

Tomas Gradin <tg@bosun.bm.lu.se> wrote:

> Ah, I see. I would do it like this:
>
> cat $FILE | awk '{print $1,$2}' | xargs -n 2 mv

now, that was a good one! :-)

Thanks a lot!!


                Bye
                        Uli

______________________________________________________________________

Uli Zappe               E-Mail: uli@tallowcross.uni-frankfurt.de
                                (NeXTMail,Mime,ASCII) PGP on request
Lorscher Strasse 5      WWW:    -
D-60489 Frankfurt       Fon:    +49 (69) 9784 0007
Germany                 Fax:    +49 (69) 9784 0042

staff member of NEXTTOYOU - the German NEXTSTEP/OPENSTEP magazine
______________________________________________________________________

Re: 2 more questions

[gwing]

Tomas Gradin wrote:
:>Actually, my task was the following:
:>    cat $FILE | mv $FIELD1_IN_LINEX_OF_FILE $FIELD2_IN_LINEX_OF_FILE
:Ah, I see. I would do it like this:
:cat $FILE | awk '{print $1,$2}' | xargs -n 2 mv

cat?  What command is that :-)
There are few, if any, reasons to use cat with zsh.  I can't think of any at
the moment, unless you're using options to it.

awk < $FILE '{print $1,$2}' | xargs -n 2 mv

-- 
Geoff Wing [mason@primenet.com.au]   Technical Manager
  Phone    : +61-3-9818 2977         PrimeNet - Internet Consultancy
  Facsimile: +61-3-9819 3788         Web : <URL:http://www.primenet.com.au/>
  Mobile   : 0412 162 441

Re: 2 more questions

[Vincent Lefevre]

On Feb 23, 1997 at 03:39:44AM +1100, gwing@primenet.com.au wrote:
> awk < $FILE '{print $1,$2}' | xargs -n 2 mv

or

awk '{print $1,$2}' $FILE | xargs -n 2 mv

-- 
Vincent Lefevre, vlefevre@ens-lyon.fr | Acorn Risc PC, StrongARM @ 202MHz
http://www.ens-lyon.fr/~vlefevre      | 20+1MB RAM, Eagle M2, TV + Teletext
PhD in Computer Science, 1st year     | Apple CD-300, SyQuest 270MB (SCSI)
-----------------------------------------------------------------------------

Re: 2 more questions (and a bug report)

[Bart Schaefer]

On Feb 23,  3:39am, gwing@primenet.com.au wrote:
} Subject: Re: 2 more questions
}
} Tomas Gradin wrote:
} :cat $FILE | awk '{print $1,$2}' | xargs -n 2 mv
} 
} There are few, if any, reasons to use cat with zsh.
} 
} awk < $FILE '{print $1,$2}' | xargs -n 2 mv

There aren't all that many reasons to use awk and xargs, either.

	while read f1 f2 ; do mv $f1 $f2 ; done < $FILE

You should even be able to say

	while read f1 f2; { mv $f1 $f2 } < $FILE

but the `while LIST { LIST }` syntax appears to have been broken in various
different ways since 3.0-pre2 or earlier.  Has this been deprecated while I
wasn't looking, and just never removed from the info file?

-- 
Bart Schaefer                             Brass Lantern Enterprises
http://www.well.com/user/barts            http://www.nbn.com/people/lantern

Re: 2 more questions

[Uli Zappe]

Geoff Wing wrote:

> There are few, if any, reasons to use cat with zsh.  I can't
> think of any at the moment, unless you're using options to it.

What about

   ARRAY=($(cat FILE))

?


                Bye
                        Uli

______________________________________________________________________

Uli Zappe               E-Mail: uli@tallowcross.uni-frankfurt.de
                                (NeXTMail,Mime,ASCII) PGP on request
Lorscher Strasse 5      WWW:    -
D-60489 Frankfurt       Fon:    +49 (69) 9784 0007
Germany                 Fax:    +49 (69) 9784 0042

staff member of NEXTTOYOU - the German NEXTSTEP/OPENSTEP magazine
______________________________________________________________________

Re: 2 more questions

[gwing]

Uli Zappe wrote:
:Geoff Wing wrote:
:> There are few, if any, reasons to use cat with zsh.  I can't
:> think of any at the moment, unless you're using options to it.
:What about
:   ARRAY=($(cat FILE))

ARRAY=($(<FILE))

Redirection in zsh is very extensive.
-- 
Geoff Wing [mason@primenet.com.au]   Technical Manager
  Phone    : +61-3-9818 2977         PrimeNet - Internet Consultancy
  Facsimile: +61-3-9819 3788         Web : <URL:http://www.primenet.com.au/>
  Mobile   : 0412 162 441

Re: 2 more questions

[Hrvoje Niksic]

gwing@primenet.com.au writes:

> There are few, if any, reasons to use cat with zsh.  I can't think
> of any at the moment, unless you're using options to it.

I use it to concatenate several files, which is what it was meant for
originally.

cat file1 file2 file3 file4 > file

is said to be a little more efficient than

<file1 <file2 <file3 <file4 > file

Somehow the cat version looks nicer, too.

-- 
Hrvoje Niksic <hniksic@srce.hr> | Student at FER Zagreb, Croatia
--------------------------------+--------------------------------
Thou Who might be our Father Who perhaps may be in Heaven...
                                                  -- Zelazny

Re: 2 more questions

[Zefram]

Hrvoje Niksic wrote:
>cat file1 file2 file3 file4 > file
>
>is said to be a little more efficient than
>
><file1 <file2 <file3 <file4 > file

I've always thought cat ought to be a shell builtin.  It's a pity there
are so many options.

-zefram