[olug] Unix Tip: EFFICIENT COMMANDS

[Unix Guru Universe]

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			      UNIX GURU UNIVERSE 
			         UNIX HOT TIP

			Unix Tip 2032 - July 25, 2003

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

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EFFICIENT COMMANDS

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.

Regards.

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


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