POSTIN
/bin/sh
if [ ! -f /etc/shells ]; then echo "/bin/tcsh" >> /etc/shells echo "/bin/csh" >> /etc/shells else grep -q /bin/tcsh /etc/shells || echo "/bin/tcsh" >> /etc/shells grep -q /bin/csh /etc/shells || echo "/bin/csh" >> /etc/shells fi
POSTUN
/bin/sh
if [ ! -x /bin/tcsh ]; then perl -ni -e 'm|/bin/t?csh| or print' /etc/shells fi