use re 'debug';
$_="abc def";
#$_= qq!"abc def$"!;

if (/"^abc[A\b]def$"/ ){
    print "\ntrue\n";
}
else
{
    print "\nfalse\n";
}
__END__
Compiling REx `"^abc[A\b]def '
size 19 Got 156 bytes for offset annotations.
first at 1
   1: EXACT <">(3)
   3: BOL(4)
   4: EXACT <abc>(6)
   6: ANYOF[\10A](17)
  17: EXACT <def >(19)
  19: END(0)
anchored ""abc" at 0 (checking anchored) minlen 9
Offsets: [19]
        1[1] 0[0] 2[1] 3[3] 0[0] 6[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 11[4] 0[0] 15[0]

false
Freeing REx: `"\"^abc[A\\b]def "'

##</code><code>##

use re 'debug';
#$_="abc def";
$_= qq!"abc def$"!;

if (/"^abc[A\b]def$"/ ){
    print "\ntrue\n";
}
else
{
    print "\nfalse\n";
}
__END__
Compiling REx `"^abc[A\b]def '
size 19 Got 156 bytes for offset annotations.
first at 1
   1: EXACT <">(3)
   3: BOL(4)
   4: EXACT <abc>(6)
   6: ANYOF[\10A](17)
  17: EXACT <def >(19)
  19: END(0)
anchored ""abc" at 0 (checking anchored) minlen 9
Offsets: [19]
        1[1] 0[0] 2[1] 3[3] 0[0] 6[5] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 0[0] 11[4] 0[0] 15[0]
Guessing start of match, REx ""^abc[A\b]def " against ""abc def "...
Found anchored substr ""abc" at offset 0...
Guessed: match at offset 0
Matching REx ""^abc[A\b]def " against ""abc def "
  Setting an EVAL scope, savestack=3
   0 <> <"abc def >       |  1:  EXACT <">
   1 <"> <abc def >       |  3:  BOL
                            failed...
Match failed

false
Freeing REx: `"\"^abc[A\\b]def "'