1# subtleties of matching 2abc & xabcy abc 3a\(b\)?c\1d b acd 4aBc i Abc Abc 5a[Bc]*d i abBCcd abBCcd 60[[:upper:]]1 &i 0a1 0a1 70[[:lower:]]1 &i 0A1 0A1 8a[^b]c &i abc 9a[^b]c &i aBc 10a[^b]c &i adc adc 11[a]b[c] - abc abc 12[a]b[a] - aba aba 13[abc]b[abc] - abc abc 14[abc]b[abd] - abd abd 15a(b?c)+d - accd accd 16(wee|week)(knights|night) - weeknights weeknights 17(we|wee|week|frob)(knights|night|day) - weeknights weeknights 18a[bc]d - xyzaaabcaababdacd abd 19a[ab]c - aaabc abc 20abc s abc abc 21a* & b @b 22