Added portable sed command for OpenBSD/NetBSD

[nerdy-sam]

Standard sed, which is used on OpenBSD and NetBSD, doesn't have the "-i" option

[mpapis]

I just did quick test and I would not be so sure that using tee to the same file is so safe, on larger files you could hit conflict between the read and written content (in my tests tee did not change Inode of the file), wouldn't it be safer to use sed ... < file > file.tmp && mv -f file.tmp file?

[nerdy-sam]

@mpapis, looks like you're right. If we were wanting to replicate the functionality of the -i option, it requires creating a temp file. This is from the sed manual....

-i[SUFFIX]
--in-place[=SUFFIX]
This option specifies that files are to be edited in-place. GNU sed does this by creating a temporary file and sending output to this file rather than to the standard output

Right now it appears as if sed's buffers are acting as our temp file, --unbuffered would probably give us a blank file.