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Sunday, February 17th, 2008

removing blank newlines using sed.

Most people won’t find this paticularly useful, but as I’m prone to forget things:

sed -e '/^$/d'

will delete blank newlines from whatever it’s input is.

1 comment
to removing blank newlines using sed.

1. leE

   on Friday, June 27th, 2008 at 1:32 pm:

   It’s actually faster to do this:

   tr -d ‘\n’

   Quick demo for you:

   $ time (cat *.txt | sed -e ‘/^$/d’ >> /dev/null)

   real 0m0.016s
   user 0m0.018s
   sys 0m0.001s

   $ time (cat *.txt | sed -e ‘/^$/d’ >> /dev/null)

   real 0m0.016s
   user 0m0.018s
   sys 0m0.001s

   $ time (cat *.txt | tr -d ‘\n’ >> /dev/null)

   real 0m0.010s
   user 0m0.011s
   sys 0m0.001s

   $ time (cat *.txt | tr -d ‘\n’ >> /dev/null)

   real 0m0.009s
   user 0m0.011s
   sys 0m0.001s

   It should also leave a smaller memory footprint:

   $ ls -lah `which tr`
   -r-xr-xr-x 1 root wheel 18K May 10 11:53 /usr/bin/tr
   $ ls -lah `which sed`
   -r-xr-xr-x 1 root wheel 33K May 10 11:53 /usr/bin/sed

   Every byte counts

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