POSTIN
/bin/sh
if [ -f /etc/shells ] then grep -q '^/bin/yash$' /etc/shells || echo '/bin/yash' >> /etc/shells else echo '/bin/yash' > /etc/shells fi exit 0
POSTUN
/bin/sh
[ "$1" = 0 ] || exit 0 [ -f /etc/shells ] || exit 0 sed -i -e '\@/bin/yash$@d' /etc/shells exit 0