Problem with glob qualifier e

Problem with glob qualifier e

[Hannu Koivisto]

Greetings,

The manual of zsh 4.2.1 says the following about the glob qualifier
e:

     filename.  In addition, the parameter reply may be set to an array
     or a string, which overrides the value of REPLY.  If set to an
     array, the latter is inserted into the command line word by word.

     For example, suppose a directory contains a single file
     `lonely'.  Then the expression `*(e:'reply=(${REPLY}{1,2})':)'
     will cause the words `lonely1 lonely2' to be inserted into the
     command line.

I can verify that the example works as described.  But I don't
understand how to extend that to more complex cases.

For instance, let's say that I would like to splice two command
line arguments after each file argument produced by a glob pattern.
If I have files sur and pur in the current directory, I would like
to say something along the lines of

echo (sur|pur)(e:'<something>':)

which, when expanded, should result to

echo pur -foo bar sur -foo bar

I expected

echo (sur|pur)(e:'reply=(${REPLY} -foo bar)':)

to do what I want but instead that results to

echo -foo -foo bar bar pur sur

I can't see how that follows from the quoted documentation.  In any
case, if my goal cannot be achieved with the glob qualifier e, is
there some other brief trick to modify the list of generated
filenames in such a way?

-- 
Hannu

Re: Problem with glob qualifier e

[Andrey Borzenkov]

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On Monday 05 September 2005 20:32, Hannu Koivisto wrote:
[...]
> echo (sur|pur)(e:'<something>':)
>
> which, when expanded, should result to
>
> echo pur -foo bar sur -foo bar
>
> I expected
>
> echo (sur|pur)(e:'reply=(${REPLY} -foo bar)':)
>
> to do what I want but instead that results to
>
> echo -foo -foo bar bar pur sur
>
> I can't see how that follows from the quoted documentation.  

List is sorted after all matches are added; meaning that anything you have 
added is reordred. Hmm ... adding qualifier that prevents sorting is 
relatively simple actually ...

> In any 
> case, if my goal cannot be achieved with the glob qualifier e, is
> there some other brief trick to modify the list of generated
> filenames in such a way?

print -l sur pur | xargs -i /bin/echo '{}' -foo bar

(I do not know why xargs here won't process arguments seperated by spaces, it 
should)

-andrey

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Re: Problem with glob qualifier e

[Bart Schaefer]

On Sep 5,  9:22pm, Andrey Borzenkov wrote:
}
} Hmm ... adding qualifier that prevents sorting is relatively simple
} actually ...

See discussion in zsh-workers/8702, 8704, 8705.

} print -l sur pur | xargs -i /bin/echo '{}' -foo bar
} 
} (I do not know why xargs here won't process arguments seperated by
} spaces, it should)

I'm not sure what you mean?  xargs never processes arguments separated
by spaces.  It always wants newlines or NULs.

Anyway, there's also

	zargs -i{} -- (sur|pur) -- echo {} -foo bar

Re: Problem with glob qualifier e

[Andrey Borzenkov]

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On Monday 05 September 2005 23:05, Bart Schaefer wrote:
> }
> } (I do not know why xargs here won't process arguments seperated by
> } spaces, it should)
>
> I'm not sure what you mean?  xargs never processes arguments separated
> by spaces.  It always wants newlines or NULs.
>

then manual page is wrong:

       This manual page documents the GNU version of xargs.  xargs reads items
       from the standard input, delimited by blanks (which  can  be  protected
       with  double or single quotes or a backslash) or newlines,

-andrey

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Re: Problem with glob qualifier e

[Bart Schaefer]

On Sep 6,  6:51am, Andrey Borzenkov wrote:
} Subject: Re: Problem with glob qualifier e
}
} 
} On Monday 05 September 2005 23:05, Bart Schaefer wrote:
} > }
} > } (I do not know why xargs here won't process arguments seperated by
} > } spaces, it should)
} >
} > I'm not sure what you mean?  xargs never processes arguments separated
} > by spaces.  It always wants newlines or NULs.
} 
} then manual page is wrong:

Ah, hmm, yes, you're right, and I've misremembered.

What I was thinking of is how xargs normally batches up its arguments.
One of the oft-stated reasons for using

    find . -whatever ... | xargs something

rather than

    find . -whatever ... -exec something {} \;

is that the latter runs something once for every file, whereas the
former runs it fewer times on groups of files.

However, my statement was correct for the case of `xargs -i' because the
manual page goes on to say:

   --replace[=replace-str], -i[replace-str]
      Replace occurences of replace-str in the initial arguments  with
      names  read  from  standard input.  Also, unquoted blanks do not
      terminate arguments.  If replace-str is omitted, it defaults  to
      "{}" (like for `find -exec').  Implies -x and -l 1.

Re: Problem with glob qualifier e

[Bart Schaefer]

On Sep 5,  7:32pm, Hannu Koivisto wrote:
} Subject: Problem with glob qualifier e
}
} For instance, let's say that I would like to splice two command
} line arguments after each file argument produced by a glob pattern.

This was discussed at some length back in April, on a zsh-users thread
with subject "globbing with interposition".

See, for example, zsh-users/8702.