Remove odd lines in a text file

Question

File:

/home/USER/DIR/a
http://www.here.is.a.hyper.link.net/
/home/USER/DIR/b
http://www.here.is.another.hyper.link.net/

Need to remove all the odd lines in this file (PUBLIC-DIRECTORY-LIST)? Its for my batch script which can be found below (dropbox batch puburl creator):

for PATH in `cat LIST`
do
echo $PATH
dropbox puburl $PATH
done > PUBLIC-DIRECTORY-LIST

Do I just append the command to prune PUBLIC-DIRECTORY-LIST at the end of the script?

Answer 1

I'd use awk for it, but that's just me:

awk '{if(i++%2)print}' foo.txt

Answer 2

# awk 'NR%2==0' file
http://www.here.is.a.hyper.link.net/
http://www.here.is.another.hyper.link.net/

Answer 3

For completeness here is the sed expression:

sed -e '1d;n;d' file

It is exactly as here except with an extra 1d command, this deletes the first line and so prints the odd lines instead of the even ones.