1*57718be8SEnji Cooper# subtleties of matching 2*57718be8SEnji Cooperabc & xabcy abc 3*57718be8SEnji Coopera\(b\)?c\1d b acd 4*57718be8SEnji CooperaBc i Abc Abc 5*57718be8SEnji Coopera[Bc]*d i abBCcd abBCcd 6*57718be8SEnji Cooper0[[:upper:]]1 &i 0a1 0a1 7*57718be8SEnji Cooper0[[:lower:]]1 &i 0A1 0A1 8*57718be8SEnji Coopera[^b]c &i abc 9*57718be8SEnji Coopera[^b]c &i aBc 10*57718be8SEnji Coopera[^b]c &i adc adc 11*57718be8SEnji Cooper[a]b[c] - abc abc 12*57718be8SEnji Cooper[a]b[a] - aba aba 13*57718be8SEnji Cooper[abc]b[abc] - abc abc 14*57718be8SEnji Cooper[abc]b[abd] - abd abd 15*57718be8SEnji Coopera(b?c)+d - accd accd 16*57718be8SEnji Cooper(wee|week)(knights|night) - weeknights weeknights 17*57718be8SEnji Cooper(we|wee|week|frob)(knights|night|day) - weeknights weeknights 18*57718be8SEnji Coopera[bc]d - xyzaaabcaababdacd abd 19*57718be8SEnji Coopera[ab]c - aaabc abc 20*57718be8SEnji Cooperabc s abc abc 21*57718be8SEnji Coopera* & b @b 22