How do I replace the last occurrence of a character in a string using sed?

How do I replace only the last occurrence of “-” in a string with a space using sed?

For example:

echo $MASTER_DISK_RELEASE
swp-RedHat-Linux-OS-5.5.0.0-03

but I want to get the following output ( replacing the last hyphen [“-“] with a space )

swp-RedHat-Linux-OS-5.5.0.0 03

Answers:

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Method 1

You can do it with single sed:

sed 's/(.*)-/1 /'

or, using extended regular expression:

sed -r 's/(.*)-/1 /'

The point is that sed is very greedy, so matches as many characters before - as possible, including others -.

$ echo 'swp-RedHat-Linux-OS-5.5.0.0-03' | sed 's/(.*)-/1 /'
swp-RedHat-Linux-OS-5.5.0.0 03

Method 2

You could also handle this with bash parameter expansion:

s=swp-RedHat-Linux-OS-5.5.0.0-03
echo ${s%-*} ${s##*-}

Output:

swp-RedHat-Linux-OS-5.5.0.0 03

Method 3

Something like this worked for me, although I’m sure there are better ways

echo "swp-RedHat-Linux-OS-5.5.0.0-03" | rev | sed 's/-/ /' | rev
swp-RedHat-Linux-OS-5.5.0.0 03

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