$ perl -Dr pipe.pl Omitting $` $& $' support. EXECUTING... Compiling REx `lo/gos' size 4 Got 36 bytes for offset annotations. first at 1 rarest char / at 2 1: EXACT (4) 4: END(0) anchored `lo/gos' at 0 (checking anchored isall) minlen 6 Offsets: [4] 1[6] 0[0] 0[0] 7[0] Guessing start of match, REx `lo/gos' against `lo/gou'... Did not find anchored substr `lo/gos'... Match rejected by optimizer Freeing REx: `lo/gos' Compiling REx `lo/gou' size 4 Got 36 bytes for offset annotations. first at 1 rarest char / at 2 1: EXACT (4) 4: END(0) anchored `lo/gou' at 0 (checking anchored isall) minlen 6 Offsets: [4] 1[6] 0[0] 0[0] 7[0] Guessing start of match, REx `lo/gou' against `lo/gou'... Found anchored substr `lo/gou' at offset 0... Guessed: match at offset 0 lo/gou Freeing REx: `lo/gou' Compiling REx `lo/gw|' size 7 Got 60 bytes for offset annotations. 1: BRANCH(5) 2: EXACT (7) 5: BRANCH(7) 6: NOTHING(7) 7: END(0) minlen 0 Offsets: [7] 0[0] 1[5] 0[0] 0[0] 6[1] 6[0] 7[0] Matching REx `lo/gw|' against `lo/gou' Setting an EVAL scope, savestack=16 0 <> | 1: BRANCH Setting an EVAL scope, savestack=22 0 <> | 2: EXACT failed... 0 <> | 6: NOTHING 0 <> | 7: END Match successful! lo/gw| Freeing REx: `lo/gw|' Compiling REx `lo/gon' size 4 Got 36 bytes for offset annotations. first at 1 rarest char / at 2 1: EXACT (4) 4: END(0) anchored `lo/gon' at 0 (checking anchored isall) minlen 6 Offsets: [4] 1[6] 0[0] 0[0] 7[0] Guessing start of match, REx `lo/gon' against `lo/gou'... Did not find anchored substr `lo/gon'... Match rejected by optimizer Freeing REx: `lo/gon'