sed in FreeBsd (every Nth Line)

[Brian Teaman]

I found that selete will delete every 3rd line with the following command.

sed '1~3d' file

However, my freeBSD (on Mac OS X) chokes on the '~' Anybody know what the freeBSD eqivalent would be?

Thanks in advance,

Brian

[Brian Teaman]

selete -> sed (oops!)

[cilu]

[ redirected ]

[SuperKoko]

A bit complex, but POSIX conforming:

{p
s/.*//
N
s/.*//
N
s/.*//
N
D
}


This may be simplified:

{p
N
N
s/.*//
N
D
}

But, this may reduce limits on line sizes.

For less trivial sed tasks, you may do a two steps sed.
First, prefixing lines by 0 or 1, indicating which type of line it is:

{s/.*/1&/
n
s/.*/0&/
n
s/.*/0&/
}

Then, since lines are tagged, you can easily pipe this output to another sed script:

/^0/d
s/^1//