[olug] Unix Tip: THE BAD AND THE GOOD

[Unix Guru Universe]

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			         UNIX HOT TIP

			Unix Tip 1902 - March 17, 2003

		    http://www.ugu.com/sui/ugu/show?tip.today

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THE BAD AND THE GOOD 

I cringe anytime I see someone code inefficiently.  Here are
three of the most common mistakes, followed by a better way to
do the same thing.

Bad:    cat somefile | grep something
Better: grep something somefile
Why:    You're running one program (grep) instead of two (cat
and grep).

Bad:    ps -ef | grep something | grep -v grep
Better: ps -ef | grep [s]omething
Why:    You’re running two commands (grep) instead of three (ps
and two greps).

Bad:    cat /dev/null > somefile
Better: > somefile
Why:    You're running a command (cat) with I/O redirection,
instead of just redirection.

Although the bad way will have the same result, the good way is
far faster.  This may seem trivial, but the benefits will really
show when dealing with large files or loops.


This tip generously supported by: sec at nbnet.nb.ca


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