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

Since there is no sample input provided by asker, I will assume a couple of cases and Bash is the input file because bash is used as the tag of the question.

Case 1: entire line is the comment

The following should be sufficient enough in most case:

sed '/^\s*#/d' file

It matches any line has which has none or at least one leading white-space characters (space, tab, or a few others, see man isspace), followed by a #, then delete the line by d command.

Any lines like:

# comment started from beginning.
         # any number of white-space character before
    # or 'quote' in "here"

They will be deleted.

But

a="foobar in #comment"

will not be deleted, which is the desired result.

Case 2: comment after actual code

For example:

if [[ $foo == "#bar" ]]; then # comment here

The comment part can be removed by

sed "s/\s*#*[^\"']*$//" file

[^\"'] is used to prevent quoted string confusion, however, it also means that comments with quotations ' or " will not to be removed.

Final sed

sed "/^\s*#/d;s/\s*#[^\"']*$//" file