UGU: Unix Guru Universe - Unix Tip #4480- June 17, 2015
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Unix Tip #4480- June 17, 2015
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.
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LAST 5 TIPS
- TOO MANY FILES AROUND
- EXTRACT RELATIVE FROM ABSOLUTE
- BELIEVE THE VENDOR?
- REMOVING CORES CONDITIONALLY
- INSERTING LINES WITHIN SCRIPTS
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