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

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 need sed -i '' …, the GNU sed Linux distributions usually come with interprets the quotes as empty input file name (instead of the backup extension), and needs sed -i … instead.

Is there any command line syntax which works with both flavors, so I can use the same script on both systems?

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.

This works with GNU sed, but not on OS X:

sed -i -e 's/foo/bar/' target.file
sed -i'' -e 's/foo/bar/' target.file

This works on OS X, but not with GNU sed:

sed -i '' -e 's/foo/bar/' target.file

On OS X you

• can't use sed -i -e since the extension of the backup file would be set to -e
• can't use sed -i'' -e for the same reasons—it needs a space between -i and ''.

When on OSX, I always install GNU sed version via Homebrew, to avoid problems in scripts, because most scripts were written for GNU sed versions.

brew install gnu-sed --with-default-names

Then your BSD sed will be replaced by GNU sed.

Alternatively, you can install without default-names, but then:

• Change your PATH as instructed after installing gnu-sed
• Do check in your scripts to chose between gsed or sed depending on your system

As Noufal Ibrahim asks, why can't you use Perl? Any Mac will have Perl, and there are very few Linux or BSD distributions that don't include some version of Perl in the base system. One of the only environments that might actually lack Perl would be BusyBox (which works like GNU/Linux for -i, except that no backup extension can be specified).

As ismail recommends,

> Since perl is available everywhere I just do perl -pi -e s,foo,bar,g target.file

and this seems like a better solution in almost any case than scripts, aliases, or other workarounds to deal with the fundamental incompatibility of sed -i between GNU/Linux and BSD/Mac.

There is no way to have it working.

One way is to use a temporary file like:

TMP_FILE=`mktemp /tmp/config.XXXXXXXXXX`
sed -e "s/abc/def/" some/file > $TMP_FILE
mv $TMP_FILE some/file

This works on both

Answer: No.

The originally accepted answer actually doesn't do what is requested (as noted in the comments). (I found this answer when looking for the reason a file-e was appearing "randomly" in my directories.)

There is apparently no way of getting sed -i to work consistently on both MacOS and Linuces.

My recommendation, for what it is worth, is not to update-in-place with sed (which has complex failure modes), but to generate new files and rename them afterwards. In other words: avoid -i.

The -i option is not part of POSIX Sed. A more portable method would be to use Vim in Ex mode:

ex -sc '%s/alfa/bravo/|x' file

1. % select all lines

2. s replace

3. x save and close

Here's another version that works on Linux and macOS without using eval and without having to delete backup files. It uses Bash arrays for storing the sed parameters, which is cleaner than using eval:

# Default case for Linux sed, just use "-i"
sedi=(-i)
case "$(uname)" in
  # For macOS, use two parameters
  Darwin*) sedi=(-i "")
esac

# Expand the parameters in the actual call to "sed"
sed "${sedi[@]}" -e 's/foo/bar/' target.file

This does not create a backup file, neither a file with appended quotes.

Steve Powell's answer is quite correct, consulting the MAN page for sed on OSX and Linux (Ubuntu 12.04) highlights the in-compatibility within 'in-place' sed usage across the two operating systems.

JFYI, there should be no space between the -i and any quotes (which denote an empty file extension) using the Linux version of sed, thus

sed Linux Man Page

#Linux
sed -i"" 

and

sed OSX Man page

#OSX (notice the space after the '-i' argument)
sed -i "" 

I got round this in a script by using an alias'd command and the OS-name output of 'uname' within a bash 'if'. Trying to store OS-dependant command strings in variables was hit and miss when interpreting the quotes. The use of 'shopt -s expand_aliases' is necessary in order to expand/use the aliases defined within your script. shopt's usage is dealt with here.

Portable script for both GNU systems and OSX:

if [[ $(uname) == "Darwin" ]]; then
    SP=" " # Needed for portability with sed
fi

sed -i${SP}'' -e "s/foo/bar/g" -e "s/ping/pong/g" foobar.txt

I ran into this problem. The only quick solution was to replace the sed in mac to the gnu version:

brew install gnu-sed

If you need to do sed in-place in a bash script, and you do NOT want the in-place to result with .bkp files, and you have a way to detect the os (say, using ostype.sh), -- then the following hack with the bash shell built-in eval should work:

OSTYPE="$(bash ostype.sh)"

cat > myfile.txt <<"EOF"
1111
2222
EOF

if [ "$OSTYPE" == "osx" ]; then
  ISED='-i ""'
else # $OSTYPE == linux64
  ISED='-i""'
fi

eval sed $ISED 's/2222/bbbb/g' myfile.txt
ls 
# GNU and OSX: still only myfile.txt there

cat myfile.txt
# GNU and OSX: both print:
# 1111
# bbbb

# NOTE: 
# if you just use `sed $ISED 's/2222/bbbb/g' myfile.txt` without `eval`,
# then you will get a backup file with quotations in the file name, 
# - that is, `myfile.txt""`

You can use sponge. Sponge is an old unix program, found in moreutils package (both in ubuntu and probably debian, and in homebrew in mac).

It will buffer all the content from the pipe, wait until the pipe is close (probably meaning that the input file is already close) and then overwrite:

From the man page:

> Synopsis > > sed '...' file | grep '...' | sponge file

The following works for me on Linux and OS X:

sed -i' ' <expr> <file>

e.g. for a file f containing aaabbaaba

sed -i' ' 's/b/c/g' f

yields aaaccaaca on both Linux and Mac. Note there is a quoted string containing a space, with no space between the -i and the string. Single or double quotes both work.

On Linux I am using bash version 4.3.11 under Ubuntu 14.04.4 and on the Mac version 3.2.57 under OS X 10.11.4 El Capitan (Darwin 15.4.0).