In-place edits with sed on OS X
I've similar problem with MacOS
sed -i '' 's/oldword/newword/' file1.txt
doesn't works, but
sed -i"any_symbol" 's/oldword/newword/' file1.txt
works well.
The -i
flag probably doesn't work for you, because you followed an example for GNU sed while macOS uses BSD sed and they have a slightly different syntax.
All the other answers tell you how to correct the syntax to work with BSD sed. The alternative is to install GNU sed on your macOS with:
brew install gsed
and then use it instead of the sed
version shipped with macOS (note the g
prefix), e.g:
gsed -i 's/oldword/newword/' file1.txt
If you want GNU sed commands to be always portable to your macOS, you could prepend "gnubin" directory to your path, by adding something like this to your .bashrc
/.zshrc
file (run brew info gsed
to see what exactly you need to do):
export PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH"
and from then on the GNU sed becomes your default sed and you can simply run:
sed -i 's/oldword/newword/' file1.txt
You can use the -i
flag correctly by providing it with a suffix to add to the backed-up file. Extending your example:
sed -i.bu 's/oldword/newword/' file1.txt
Will give you two files: one with the name file1.txt
that contains the substitution, and one with the name file1.txt.bu
that has the original content.
Mildly dangerous
If you want to destructively overwrite the original file, use something like:
sed -i '' 's/oldword/newword/' file1.txt
^ note the space
Because of the way the line gets parsed, a space is required between the option flag and its argument because the argument is zero-length.
Other than possibly trashing your original, I’m not aware of any further dangers of tricking sed this way. It should be noted, however, that if this invocation of sed
is part of a script, The Unix Way™ would (IMHO) be to use sed
non-destructively, test that it exited cleanly, and only then remove the extraneous file.