Shell Programming and Scripting

#!/bin/ksh

user=$1   # 1st arg, recipient
file=$2   # 2nd arg, file containing message

if [[ ! -n "${user}" ]]; then
        echo "you did not enter a user, aborting"
        exit 0
fi

# if no file, enter one line to send
#
if [[ ! -f "${file}" ]]; then
        echo "enter a one line message to send to ${user}"
        read line
        if [[ -n "${line}" ]]; then
                echo "${line}" > $0.$$
                file=$0.$$
        else
                echo "you did not enter any text, aborting"
                exit 0
        fi
fi

# write the file to all sessions of the user
#
for u in $(who | grep "^${user} " | awk '{print $1":"$2}'); do
        a=$(echo "${u}" | cut -d: -f1,1)
        b=$(echo "${u}" | cut -d: -f2,2)
        cat ${file} |write $a $b
done

# remove temp file if exists
#
if [ -f $0.$$ ]; then
        rm $0.$$
fi