sed in-place flag that works both on Mac (BSD) and Linux

Question

Is there an invocation of sed todo in-place editing without backups that works both on Linux and Mac? While the BSD sed shipped with OS X seems to

Answer 1

If you really want to just use sed -i the 'easy' way, the following DOES work on both GNU and BSD/Mac sed:

sed -i.bak 's/foo/bar/' filename

Note the lack of space and the dot.

Proof:

# GNU sed
% sed --version | head -1
GNU sed version 4.2.1
% echo 'foo' > file
% sed -i.bak 's/foo/bar/' ./file
% ls
file  file.bak
% cat ./file
bar

# BSD sed
% sed --version 2>&1 | head -1
sed: illegal option -- -
% echo 'foo' > file
% sed -i.bak 's/foo/bar/' ./file
% ls
file  file.bak
% cat ./file
bar

Obviously you could then just delete the .bak files.