How to UNCOMMENT a line that contains a specific string using Sed?

Question

The lines in the file :

-A INPUT -m state --state NEW -m tcp -p tcp --dport 2000 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 2001 -j ACCEPT
-A          


        

Answer 1

Quick example of how to comment and uncomment a line in a file.

Sample file :

umask 027
TMOUT=600

Lets now backup the file (just for laughs) and comment out and un comment:

# backup file (because we should always do this)
cp /etc/bash.bashrc /etc/bash.bashrc.$(date '+%Y-%m-%d,%H:%M:%S')

# original: TMOUT=600   , result :# TMOUT=600
sed -i '/[^#]/ s/\(^TMOUT=600.*$\)/#\ \1/' /etc/bash.bashrc

# original # TMOUT=600   ,result :TMOUT=600
sed -i '/^#.*TMOUT=600.*$/s/^#\ //' /etc/bash.bashrc