RE: Scripting help please

["Collins, Kevin [MindWorks]" <KCollins chevrontexaco com>]

Sure, but then why not do?

 cat $file | awk '{print}' | while read line
 do
	echo "$line"
 done | perl -F\\$ -nae '$F[1] =~ s/,/*/g; print join("\$", @F)'

The answer: because it is redundant and not necessary. Perl and sed and
awk and most other "filters" know how to open a file, so give them a
file and let them do their job. Your teaching someone, so teach them the
right way...

Kevin

-----Original Message-----
From: taroon-list-bounces redhat com
[mailto:taroon-list-bounces redhat com] On Behalf Of John Haxby
Sent: Wednesday, May 04, 2005 8:29 AM
To: Discussion of Red Hat Enterprise Linux 3 (Taroon)
Subject: Re: Scripting help please

Collins, Kevin [MindWorks] wrote:

>Useless use of cat! Try:
>
> perl -F\\$ -nae '$F[1] =~ s/,/*/g; print join("\$", @F)' file
>  
>

I know I'm name dropping, but Brian Kernighan said the same thing some 
time ago ('83, I think, but it was a while ago.).   He was commenting on

"cat xxx | yyy" vs "yyy < xxx" (or even "<xxx yyy").

Having thought about it, his conclusion was that you shouldn't worry 
about it.   With something like the perl script, the performance 
advantage is minimal.   On the other hand, "cat file | awk 
'fifty-line-awk-script'" is more likely to be readable than "awk 
'fifty-line-awk-script" file".   My personal style depends on how I'm 
feeling: I might like the challenge of using just the shell or just sed,

or I might want to try a different approach.   Or I might be writing 
something that has to be maintained -- in which case clarity and 
readability move way up the list.

jch

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