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List:       coreutils
Subject:    Re: Dog & cat
From:       Bob Proulx <bob () proulx ! com>
Date:       2013-09-18 18:04:40
Message-ID: 20130918180440.GA15570 () hysteria ! proulx ! com
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Pádraig Brady wrote:
> Pascal wrote:
> > cat - "concatenate files and print on the standard output" -
> > offers -s option to suppress repeated empty lines.
> > 
> > However, an "empty" line (visual perspective) that behave only
> > spaces or tabs is not considered as empty : one option -S that
> > would address this scenario should be added to cat...
> > 
> > I hope to be clear :-)
> 
> While it's a fair suggestion, I'd be against adding this functionality to cat
> as it's outside of its core functionality.
> 
> Now even `cat -s` is debatable, but at least that is also implemented in FreeBSD
> and is an awkward enough operation to do in sed for example:
> http://www.gnu.org/software/sed/manual/html_node/cat-_002ds.html
> 
> However a simple additional sed operation would suffice to implement -S.
> Something like: sed 's/^ *$//' | cat -s
> 
> So I'd be 70:30 against implementing this.

I would also vote against this functionality.

  http://harmful.cat-v.org/cat-v/
  Rob Pike wrote:
  > The talk reviews reasons for UNIX's popularity and shows, using UCB
  > cat as a primary example, how UNIX has grown fat. cat isn't for
  > printing files with line numbers, it isn't for compressing multiple
  > blank lines, it's not for looking at non-printing ASCII characters,
  > it's for concatenating files.

Additionally I will note that on in some systems (at least SunOS)
'cat -s' does not squeeze lines but suppresses errors about
non-existent files.  It is terribly non-portable.  Using
--squeeze-blank at least will noisily break if not using a compatible
cat program.

Bob


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