Home / server / Questions / 810033
Accepted
Roger Creasy
Asked: 2016-10-20 09:10:55 +0800 CST

sed insert line on first blank line after XXX

  • 772

I am interactively editing my hosts file with a bash script. I need to insert a line in my hosts file. The line needs to be inserted on the first blank line after a specific comment. The content I am inserting is in a variable.

Here is what I tried ($NEWLINE is set previously):

sed -i '# Insert New DNS / Virtualbox/$NEWLINE/g' /etc/hosts

I get no error, but the line is not written. Any advice?

bash sed

1 Answers

  1. Best Answer

    Suppose:

    # Insert New DNS

    is the line after which you want to insert at first empty line:

    You can achieve this by the following command:

     sed -i '/# Insert New DNS/,/^$/s/^$/'"$NEWLINE"'/' /etc/hosts

    The following will search for line numbers (addresses) in the file:

    /# Insert New DNS/,/^$/

    The following will replace the "empty line"

    s/^$/'"$NEWLINE"'/
    • 5