Require Password Change script v2.

#!/bin/bash

#Defines

SALT_CHARS="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
SALT_LENGTH="2"
PW_CHARS="1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz!@#$%^&*()."
PW_LENGTH="8"

#Checks

if [ "$(whoami)" != 'root' ]; then
   echo "This program must be run as root"
   exit 1;
 elif [ -z $1 ]; then
    echo "Usage: pwexpire <username>"
    exit 1;
 elif [ ! `grep $1 /etc/passwd` ] ; then
    echo "$1 not found. Please ensure the user account exists."
    exit 1;
 elif [ ! -f /usr/bin/python ] ; then 
    echo "Python not found in /usr/bin!"
    exit 1;
fi

#Salt Generation
#Uses a numeric value if CHOICE returns 1; characters if 0
#since python's crypt function will only take one or the other (AFAIK)

CHOICE=`expr $RANDOM % 2`
if [ "$CHOICE" = 0 ]; then
   while [ "${n:=1}" -le "$SALT_LENGTH" ]; do
      NUMBER=$RANDOM
      let "NUMBER %= 26"
      if [ $NUMBER != 0 ]; then
         SALT=$SALT$(echo $SALT_CHARS | cut -c $NUMBER)
         let n+=1
      fi
   done
else
   NUMBER=$RANDOM
   let "NUMBER %= 99"
      if [[ $NUMBER < 10 ]]; then
         NUMBER=$NUMBER$(expr $NUMBER + $RANDOM % 10)
      fi
   SALT=$NUMBER
fi

#Password handling

echo -e "Generate random password? (Y/n) \c"
read YESNO

case "$YESNO" in
 "Y" | "y" | "")
 echo "Generating $PW_LENGTH character password..."
 n=1  #re-initialize
 while [ "$n" -le "$PW_LENGTH" ]; do
    NUMBER=$RANDOM
    let "NUMBER %= ${#PW_CHARS}"
    if [ $NUMBER != 0 ]; then
       PASS=$PASS$(echo $PW_CHARS | cut -c $NUMBER)
       let n+=1
    fi
 done
 ;;

 "N" | "n")
 echo -e "Please enter the temporary password: \c "
 read PASS
 ;;

 *) echo "Exiting."
 exit 0;
 ;;
esac

#Account Maintenenace

PWHASH=`/usr/bin/python -c "import crypt; print crypt.crypt(\"$PASS\",\"$SALT\")"` 

if [ $PWHASH ]; then
   usermod -L $1 && chage -d 0 $1 && usermod -p "$PWHASH" $1
   echo "Operation successful." 
   echo -e "User account \"$1\" will require a password change on next login\n"
   echo -e "Please record the following details:\n"
   echo "---"
   echo "Account name: $1"
   echo "Temporary password: $PASS"
   echo "---" 
   exit 0;
 else echo "An error has occured. Please re-run this program"
    exit 1;
fi