in reply to extract only uppercases from string
$ perl -E ' > $str = q{G_I1E2_GTGGAG^303CTGgacgCCCTGC_I2E3_TACA}; > say for > map { tr{[ACGT]}{}cd; $_ } > split m{[a-z]+}, $str;' GGTGGAGCTG CCCTGCTACA $ [download]
Cheers,
JohnGG