Question

I have lines with a single : and a' in them that I want to get rid of. I want to use awk for this. I’ve tried using:

 awk '{gsub ( "[:\\']","" ) ; print $0 }'

and

 awk '{gsub ( "[:\']","" ) ; print $0 }'

and

 awk '{gsub ( "[:']","" ) ; print $0 }'

non of them worked, but return the error Unmatched ".. when I put

 awk '{gsub ( "[:_]","" ) ; print $0 }'

then It works and removes all : and _ chars. How can I get rid of the ' char?

Answer 1

You could use:

1. Octal code for the single quote:

   [:\47]
   

2. The single quote inside double quotes, but in that case special
   characters will be expanded by the shell:

   % print a\': | awk "sub(/[:']/, x)"        
   a
   

3. Use a dynamic regexp, but there are performance implications related
   to this approach:

   % print a\': | awk -vrx="[:\\\']" 'sub(rx, x)'  
   a