auth sufficient pam_exec.so \
  quiet seteuid \
  /usr/bin/awk -F: [ \
    BEGIN { ret = 1 } \
    $1 == ENVIRON["PAM_USER"\] && $2 == "x" { ret = 0 } \
    END { exit ret }] /etc/passwd

account sufficient pam_exec.so \
  quiet seteuid \
  /usr/bin/awk -F: [ \
    BEGIN { ret = 1 } \
    $1 == ENVIRON["PAM_USER"\] && $2 == "x" { ret = 0 } \
    END { exit ret }] /etc/passwd