[SOLVED] Delete or Replace nth line in a file after a pattern match using shell scripts

Issue

I need to replace 11th line after the pattern match "msq_Query" in a file, the original text should remain intact. A one-liner sed or awk would be helpful !!

*msq_Query
{
    { BaconOutput1, 0419000000, 0144567891,
        <
        OIN ,
        TIN ,
        BPARTY
        >
    ,
        <
        >
    , 1477361456, 0}
}

In the 11th line in the file, number (whihc could be random) should be replaced by 0 OR 11th line should be deleted .

Solution

I think the easiest way to do this would be with awk like this:

awk -v lines=11 'BEGIN { ignore = -1 } /pattern/ { ignore = NR + lines } NR != ignore { print }' filename

Substitute pattern with your own pattern.

This works as follows:

BEGIN { ignore = -1 }             # initialize ignore with -1 so NR will never
                                  # be equal to it by accident

/pattern/ { ignore = NR + lines } # when the pattern is found, set ignore to the
                                  # line we want to ignore

NR != ignore { print }            # unless the current line is that line, print
                                  # it.

In order to replace something in the line instead of deleting it, the script can be amended as follows:

awk -v lines=11 'BEGIN { mark = -1 } /pattern/ { mark = NR + lines } NR == mark { sub(/[0- 9]+/, "") } { print }' filename

that is:

BEGIN { mark = -1 }                # initialize mark with -1 so NR will never
                                   # be equal to it by accident

/pattern/ { mark = NR + lines }    # when the pattern is found, set mark to the
                                   # line we want to ignore

NR == mark { sub(/[0-9]+/, "0"); } # if that line is the current line, substitute
                                   # stuff (stuff can be freely chosen)

{ print }                          # print all the lines.

Answered By - Wintermute

Answer Checked By - Marilyn (WPSolving Volunteer)