$ echo 'ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA > ACATCACCTCCCACAACGAGGACTACACCATCGTGGAACA' | perl -nE 'say substr($_, 10, 1);' C C C C C C C C C C C C C