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

I would recommend using awk for this:

awk '!/^Header/ || !f++' file

This prints all lines that don't start with "Header". Short-circuit evaluation means that if the left hand side of the || is true, the right hand side isn't evaluated. If the line does start with Header, the second part !f++ is only true once.

$ cat file
baseball
Header and some other stuff
aardvark
Header for the second time and some other stuff
orange
$ awk '!/^Header/ || !f++' file
baseball
Header and some other stuff
aardvark
orange