Bash regex to match quoted string - regex

Question

I’m trying to come up with a regular expression I can use to match strings surrounded by either single or double quotation marks. The regex should match all of the following strings:
"ABC&VAR#"
'XYZ'
"ABC.123"
'XYZ&VAR#123'
Here is what I have so far:
^([\x22\x27]?)[\w.&#]+\1$
\x22 represents the " character, and \x27 is the ' character.
This works in RegExr, but not in Bash comparisons using the =~ operator. What am I overlooking?
Update: The problem was that my regex uses two features of PCRE syntax that Bash does not support: the \w atom, and backreferences. Thanks to Inian for reminding me of this. I decided to use grep -oP instead of Bash’s built-in =~ operator, so that I can take advantage of PCRE niceties. See my comment below.

Answer 1

BASH regex doesn't support back-reference. In BASH you can do this.
arr=('"ABC&VAR#"' "'XYZ'" '"ABC.123"' "'XYZ&VAR#123'" "'foobar\"")
re="([\"']).*(['\"])"
for s in "${arr[#]}"; do
[[ $s =~ $re && ${BASH_REMATCH[1]} = ${BASH_REMATCH[2]} ]] && echo "matched $s"
done
Additional check ${BASH_REMATCH[1]} = ${BASH_REMATCH[2]} is being done to make sure we have same opening and closing quote.
Output:
matched "ABC&VAR#"
matched 'XYZ'
matched "ABC.123"
matched 'XYZ&VAR#123'

Answer 2

You can use regexp (\"|\').*(\"|\') for egrep.
Here is my example of how does it work:
a="\"ABC&VAR#\""
b="'XYZ'"
c="\"ABC.123\""
d="'XYZ&VAR#123'"
echo "Line correct: ${a} and ${b} and ${c} and ${d}"
if [ `echo "${a}" | egrep "(\"|\').*(\"|\')"` -o `echo "${b}" | egrep "(\"|\').*(\"|\')"` -o `echo "${c}" | egrep "(\"|\').*(\"|\')"` -o `echo "${d}" | egrep "(\"|\').*(\"|\')"` ]
then
echo "Found"
else
echo "Not Found"
fi
Output:
Line correct: "ABC&VAR#" and 'XYZ' and "ABC.123" and 'XYZ&VAR#123'
Found
To avoid so long if expression, use array for example for your variables.
In this case you will have something like that:
a="\"ABC&VAR#\""
b="'XYZ'"
c="\"ABC.123\""
d="'XYZ&VAR#123'"
arr=( "\"ABC&VAR#\"" "'XYZ'" "\"ABC.123\"" "'XYZ&VAR#123'" )
for line in "${arr[#]}"
do
[ `echo "${line}" | egrep "(\"|\').*(\"|\')"` ] && echo "Found match" || echo "Matches not found"
done