How can you use sed to replace spaces with periods and still keep () and []

Question

I want to remove all special characters leaving only A-Za-z0-9.()[]

echo 'Some Movie Name! (2015) [1080p]' |sed -e 's/[^A-Za-z0-9.()[]]/./g'

Gives me this output:

Some Movie Name! (2015) [1080p]

This is what I want:

Some.Movie.Name.(2015).[1080p]

I cant figure out how to escape the "]" "]" doesn't work.

The closest I can get is this:

echo 'Some Movie Name! (2015) [1080p]' |sed -e 's/[^A-Za-z0-9.()[]/./g'
Some.Movie.Name..(2015).[1080p.

Then I can pipe it to sed again to remove double periods:

|sed 's/\.\././g'

Answer 1

Based on @Glenn Jackman's keen observations the method is changed to the following:

$ printf '%s' "$string" | tr -cs '[:alnum:].[]()'


°  -c => invert/complement the input set
°  -s => will squeeze consecutive characters from the complemented input set found in the data to a single dot character. 

Answer 2

Put the closing ] you want to match directly after the negation ^ where it is not misinterpreted. You can use \+ at the end of the regex to replace multiple characters with one period (thanks @Rakesh Sharma):

$ echo 'Some Movie Name! (2015) [1080p]' | sed -e 's/[^][A-Za-z0-9()]\+/./g'
Some.Movie.Name.(2015).[1080p]