Useful one-liners

Some useful one liners for bash scripting....

Removing the lines that start with #

cat file.conf | sed '/ *#/d; /^ *$/d'

Replacing text within configuration files (replace yes with no when PRELINKING)

sed '/PRELINKING/s/yes/no/g' /etc/sysconfig/prelink > /etc/sysconfig/prelink.new 

awk '/PRELINKING/{gsub(/yes/, "no")};{print}' /etc/sysconfig/prelink > /etc/sysconfig/prelink.new

Delete all blank lines on a file

sed '/^$/d' filename

Number lines (except blank ones)

awk 'NF{$0=++a " :" $0};{print}' filename

to be updated...