Delete all comments in a file using sed

Question

How would you delete all comments using sed from a file(defined with #) with respect to \'#\' being in a string?

This helped out a lot except for the string portion.

Answer 1

This might work for you (GNU sed):

sed '/#/!b;s/^/\n/;ta;:a;s/\n$//;t;s/\n\(\("[^"]*"\)\|\('\''[^'\'']*'\''\)\)/\1\n/;ta;s/\n\([^#]\)/\1\n/;ta;s/\n.*//' file

• /#/!b if the line does not contain a # bail out
• s/^/\n/ insert a unique marker (\n)
• ta;:a jump to a loop label (resets the substitute true/false flag)
• s/\n$//;t if marker at the end of the line, remove and bail out
• s/\n\(\("[^"]*"\)\|\('\''[^'\'']*'\''\)\)/\1\n/;ta if the string following the marker is a quoted one, bump the marker forward of it and loop.
• s/\n\([^#]\)/\1\n/;ta if the character following the marker is not a #, bump the marker forward of it and loop.
• s/\n.*// the remainder of the line is comment, remove the marker and the rest of line.