Sed/Awk to delete second occurence of string - platform independent

Question

I\'m looking for a line in bash that would work on both linux as well as OS X to remove the second line containing the desired string:

Header
1
2
...
Header
10
1         


        

Answer 1

This might work for you (GNU sed):

sed -i '1b;/^Header/d' file

Ignore the first line and then remove any occurrence of a line beginning with Header.

To remove subsequent occurrences of the first line regardless of the string, use:

sed -ri '1h;1b;G;/^(.*)\n\1$/!P;d' file