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Date: Fri, 24 Sep 2004 12:25:07 +1200
From: Juha Saarinen <juhasaarinen@gmail.com>
To: Giorgos Keramidas <keramida@linux.gr>
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Subject: Re: Could ARG_MAX be increased?
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On Fri, 24 Sep 2004 03:03:13 +0300, Giorgos Keramidas <keramida@linux.gr> wrote:
> The friend is correct.  This is a nice trick.
> 
> xargs will construct a command line by appending one or more filenames
> to what you pass.  The important part being ``one or more''.
> 
> If xargs appends one filename to an argument list of `grep foo', the
> executed command is `grep foo filename', which will not list the name of
> the file with every match since grep sees only 1 filename argument.
> 
> If the argument list passed to xargs is `grep foo /dev/null' though, the
> executed command is `grep foo /dev/null filename'; in this case the
> filenames grep sees are always at least 2, which enables printing the
> filename with every match.
> 
> This is better illustrated with an example:
> 
> $ grep PS1 .bashrc
> export PS1='${USER}@\h[\A]${PWD}\$ '
> $ grep PS1 /dev/null .bashrc
> .bashrc:export PS1='${USER}@\h[\A]${PWD}\$ '

Well, learn something new every day :-)

Thanks for the explanation.


-- 

Juha