CODEWITHSUNDEEP
regexbashsed
octosquidopus
octosquidopus

Reputation: 3713

Escaping single quote in a sed command containing variables containing color escape codes?

I'm using sed to replace every instance of " is " by a colorized "'s ".

To do this, it surrounds the result by a color variable r and a blank variable x, which are interpreted literally. echo -e then makes the colors appear. Nothing new here.

The problem arises when I try to add the apostrophe (which is actually a single quote); I can't escape it without messing up the color escape code.

Here is my code without the apostrophe I'm trying to add:

r='\e[0;31m'                    # red
x='\e[0m'                       # reset color
sed 's/ is /\'${r}'s\'${x}'/g'  # replace " is " by "'s "

I tried double quotes, multiple backslashes, but everything either broke the color code, or failed to escape the single quote. In the meantime, I'm using a true apostrophe ( ’ ), but it it's not the best solution, because it doesn't render properly in the TTY.

Upvotes: 0

Views: 477

Answers (1)

Aaron Digulla
Aaron Digulla

Reputation: 328754

If you want to keep the single quotes, then you need '"'"'

The first quote ends the current single quoted string. Then we have "'" which expands to a single quote. \' would also work but doesn't look as good.

The last single quote starts the quoted string again.

An alternative in your case would be "s/ is /${r}'s${x}/g" (i.e. only use double quotes).

But then, you need to use r='\\e[0;31m' because the expansion in the string will string one level of escapes.

Upvotes: 1

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