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UGU: Unix Guru Universe - Unix Tip #4281- November 30, 2012
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 Unix Tip #4281- November 30, 2012
 
POWER OF XARGS  
  
Don't over look the power of xargs. By default  
in some flavors of unix, the command line is  
limited to roughly 20K bytes.  
  
Some directory lists can well exceed that.  
  
Secondly, performance using  
  
% find /tmp -name foo -exec rm \;  
  
will fork the rm command for every file it  
finds. If this were to return 1000s of files  
you get rm forked 1000s of times.  
  
But,  
  
% find /tmp -name foo |xargs rm  
  
while getting the same effect, rm is forked  
with a long list of files, and thus system  
overhead is reduced, and the command runs  
faster, and system impact is reduced.  
  
This is also important if you have list of  
files produced by  
  
% find {blah} > listfile  
  
Once you edit your list to remove those  
files you really want to keep, then  
  
% cat listfile| xargs rm  
  
Will remove all the files in the file. While  
% rm $(cat listfile) will  
  
Fail if listfile is greater than ~20K  
  
  
 NOTE: All tips provided are USE AT YOUR OWN RISK. Tips are submitted
by various unix admins around the globe. UGU suggest you read and
test each tip in a non-volitile environment before placing into
production.
  
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