#!/bin/bash

# this script searches for the user ids which have not been used for a specific
# number of days


# the number of days to be monitored
expdays=30
expiry=$(( 86400*$expdays ))

LOG1=/tmp/inactive_usr_$expdays_days.$( date '+%m-%d-%Y' ).log
LOG2=/tmp/never_logged_usrs.$( date '+%m-%d-%Y' ).log
tmp1=/tmp/tmp1.log.$$

# list out the accounts which can be used to log in to the server

cat /etc/passwd | grep -Ev ^"root|daemon|nobody|adm|sys" | cut -d ":" -f1 >>$tmp1

# date and time calculation with respect to unix epoch

year=$( date +%Y )

today=$( date +%s )

# now, for each of the user listed above, run a check if the last logged in time exceedes the specified number of days.

cat $tmp1 | while read usr; do
        umnt=$( last -1 $usr | head -1 | awk '{ print $5 }' )
        uday=$( last -1 $usr | head -1 | awk '{ print $6 }' )
        uhour=$( last -1 $usr | head -1 | awk '{ print $7 }' | cut -d ":" -f1 )
        umin=$( last -1 $usr | head -1 | awk '{ print $7 }' | cut -d ":" -f2 )

        # the below line checks and stores the IDs which were never used
        if [ ! $uday ] || [ ! $uhour ] || [ ! $umin ]; then
            echo "$usr:__NeveR__" >>$LOG2
        else
            llogin=$( date +%s -d"$umnt $uday, $year $uhour:$umin:01" )
            mini=$(( $today-$llogin ))
            if [[ $mini -gt $expiry ]]; then
                login=$(( ($today-$llogin)/86400 ))
                echo "$usr:$login" >>$LOG1
            fi
        fi
done

rm -f $tmp1