UNIX for Dummies Questions & Answers

Hi,

I have one basic doubt, that using grep command frequently , will it have direct impact on the CPU load, pls clarify

for eg, if i run a non stop script containing while loop to grep some parameters, what will be the load in CPU..

thanks

It does. But I dont think there is a direct (or indirect) proportion between them.

Run a grep which goes recursive into the sub directories.

And then issue top. You can see under the %CPU column for the CPU% used for grep.

vino

Definitely it does have an impact on CPU usage.

The resources used are in proportion to the complexity of patter.
For eg: for fixed string it will be less. for regular expression it will be more.

To make use of different algorithms for most efficient searches there are seperate binaries itself.

like we have
egrep: extended grep - for regular expression searches
fgrep: fast grep: used for fixed searches across multiple files.

for more information see man pages

thanks,
rishi

It sure does, so my advice to you is to "grep smartly", so you narrow down your search as fast as you can, then pipe the results into another grep for processing. While experimenting with scripts, I have brought down my share of servers using grep only (but I can't resist huge one-liners).

Also, when you want an endless loop running, it might be wise to use the sleep-command to add in a pause of a few seconds, just to free up some resources.