Solaris

PATH=/bin:/usr/bin:/usr/sbin:/usr/sfw/bin:/opt/csw/bin
export PATH

# Solaris has no tool to set a password non-interactively.
# Using "expect" has many risks. So we directly edit /etc/shadow.
sol_pwd()
{
ETCSHADOW=/etc/shadow
DATECHG=`perl -e 'print int time/86400'`
# Backup with owner/permission
if
  cp -p ${ETCSHADOW} ${ETCSHADOW}- &&
  cp -p ${ETCSHADOW} ${ETCSHADOW}.aux &&
# Overwrite the files; owner/permission and line order remains
  awk '
    BEGIN { FS=OFS=":" }
    ($1==user) { $2=hash; $3=datechg }
    { print }
  ' user="$ID" hash="$HASH" datechg="$DATECHG" < ${ETCSHADOW} > ${ETCSHADOW}.aux
then
  # *LK* in pw-hash and 0 in lastchg was overwritten. passwd -u is not necessary
  mv -f ${ETCSHADOW}.aux ${ETCSHADOW}
fi
} # sol_pwd

# main

echo "Enter user:"
read ID
echo "Enter pw:"
read PASS
if [ -z "$ID" ] || [ ${#PASS} -lt 3 ]
then
  exit
fi
HASH=`echo "${PASS}" | openssl passwd -stdin` || exit
sol_pwd