Stripping single and double quotes in a string usi

Question

I'm looking for something that will translate a string as follows, using only bash / standard Linux commands:

1. Single-quotes surrounding a string should be removed
2. Double-quotes surrounding a string should be removed
3. Unquoted strings should remain the same
4. Strings with unmatched surrounding quotes should remain the same
5. Single-quotes that don't surround the string should remain
6. Double-quotes that don't surround the string should remain

For example:

• 'Food' should become Food
• "Food" should become Food
• Food should remain the same
• 'Food" should remain the same
• "Food' should remain the same
• 'Fo'od' should become Fo'od
• "Fo'od" should become Fo'od
• Fo'od should remain the same
• 'Fo"od' should become Fo"od
• "Fo"od" should become Fo"od
• Fo"od should remain the same

Thank you!

Answer 1

Just using Bash builtins (i.e. Bash parameter expansion):

IFS=' ' 

food_strings=( "'Food'" '"Food"' Food "'Food\"" "\"Food'" "'Fo'od'" "\"Fo'od\"" "Fo'od" "'Fo\"od'" '"Fo"od"' 'Fo"od'  )  

for food in ${food_strings[@]}; do 

   [[ "${food#\'}" != "$food" ]] && [[ "${food%\'}" != "$food" ]] && { food="${food#\'}"; food="${food%\'}"; } 

   [[ "${food#\"}" != "$food" ]] && [[ "${food%\"}" != "$food" ]] && { food="${food#\"}"; food="${food%\"}"; } 

   echo "$food"

done 

For yet another example of Bash parameter expansion see:

http://codesnippets.joyent.com/posts/show/1816