Bash script to check command-line arguments and set default if not present

if [ -n "$1" ]
# Test whether command-line argument is present (non-empty).
then
lines=$1
else
lines=$LINES # Default, if not specified on command-line.
fi

how to encrypt your scripts using sch

Dont want to give your scripts to any one but want to give someone to execute for specific period of time then this is what you are looking for .
We can also give timeline in which the script can be used.

Also you will not be revealing you passwords in the script.

SCH will encrypt shell scripts using RC4 and make executable binary.

http://www.datsi.fi.upm.es/~frosal/sources/shc-3.8.7.tgz

shc [ -e date ] [ -m addr ] [ -i iopt ] [ -x cmnd ]
[ -l lopt ] [ -ACDhTv ] -f script

shc -e date ( script will not run afterdate specified )
-m "Please contact support " (message to display after we run the expired scirpt)

shc -e 01/06/2010 -m "You are late to run this script." -f script.sh

./script.sh.x



http://www.datsi.fi.upm.es/~frosal/sources/shc.html

I have tried to hack the encrypted binary that came as output, but was not successful
I used bashdb and GDB

Per user mac based bandwidth monitor for routers


Want to calculate how much bandwidth each user (mac address) is using


    ./wrtbwmon setup
   ./wrtbwmon update /tmp/usage.db offpeak
   ./wrtbwmon publish /tmp/usage.db /www/user/usage.htm /jffs/users.txt

Here is open source solution ClickHere

Below is the script  (wrtbwmon )
---------------------------

LAN_IFACE=$(nvram get lan_ifname)

lock()
{
while [ -f /tmp/wrtbwmon.lock ]; do
if [ ! -d /proc/$(cat /tmp/wrtbwmon.lock) ]; then
echo "WARNING : Lockfile detected but process $(cat /tmp/wrtbwmon.lock) does not exist !"
rm -f /tmp/wrtbwmon.lock
fi
sleep 1
done
echo $$ > /tmp/wrtbwmon.lock
}

unlock()
{
rm -f /tmp/wrtbwmon.lock
}

case ${1} in

"setup" )

#Create the RRDIPT CHAIN (it doesn't matter if it already exists).
iptables -N RRDIPT 2> /dev/null

#Add the RRDIPT CHAIN to the FORWARD chain (if non existing).
iptables -L FORWARD --line-numbers -n | grep "RRDIPT" | grep "1" > /dev/null
if [ $? -ne 0 ]; then
iptables -L FORWARD -n | grep "RRDIPT" > /dev/null
if [ $? -eq 0 ]; then
echo "DEBUG : iptables chain misplaced, recreating it..."
iptables -D FORWARD -j RRDIPT
fi
iptables -I FORWARD -j RRDIPT
fi

#For each host in the ARP table
grep ${LAN_IFACE} /proc/net/arp | while read IP TYPE FLAGS MAC MASK IFACE
do
#Add iptable rules (if non existing).
iptables -nL RRDIPT | grep "${IP} " > /dev/null
if [ $? -ne 0 ]; then
iptables -I RRDIPT -d ${IP} -j RETURN
iptables -I RRDIPT -s ${IP} -j RETURN
fi
done
;;
"update" )
[ -z "${2}" ] && echo "ERROR : Missing argument 2" && exit 1
# Uncomment this line if you want to abort if database not found
# [ -f "${2}" ] || exit 1

lock

#Read and reset counters
iptables -L RRDIPT -vnxZ -t filter > /tmp/traffic_$$.tmp

grep -v "0x0" /proc/net/arp  | while read IP TYPE FLAGS MAC MASK IFACE
do
#Add new data to the graph. Count in Kbs to deal with 16 bits signed values (up to 2G only)
#Have to use temporary files because of crappy busybox shell
grep ${IP} /tmp/traffic_$$.tmp | while read PKTS BYTES TARGET PROT OPT IFIN IFOUT SRC DST
do
[ "${DST}" = "${IP}" ] && echo $((${BYTES}/1000)) > /tmp/in_$$.tmp
[ "${SRC}" = "${IP}" ] && echo $((${BYTES}/1000)) > /tmp/out_$$.tmp
done
IN=$(cat /tmp/in_$$.tmp)
OUT=$(cat /tmp/out_$$.tmp)
rm -f /tmp/in_$$.tmp
rm -f /tmp/out_$$.tmp
if [ ${IN} -gt 0 -o ${OUT} -gt 0 ];  then
echo "DEBUG : New traffic for ${MAC} since last update : ${IN}k:${OUT}k"
LINE=$(grep ${MAC} ${2})
if [ -z "${LINE}" ]; then
echo "DEBUG : ${MAC} is a new host !"
PEAKUSAGE_IN=0
PEAKUSAGE_OUT=0
OFFPEAKUSAGE_IN=0
OFFPEAKUSAGE_OUT=0
else
PEAKUSAGE_IN=$(echo ${LINE} | cut -f2 -s -d, )
PEAKUSAGE_OUT=$(echo ${LINE} | cut -f3 -s -d, )
OFFPEAKUSAGE_IN=$(echo ${LINE} | cut -f4 -s -d, )
OFFPEAKUSAGE_OUT=$(echo ${LINE} | cut -f5 -s -d, )
fi
if [ "${3}" = "offpeak" ]; then
OFFPEAKUSAGE_IN=$((${OFFPEAKUSAGE_IN}+${IN}))
OFFPEAKUSAGE_OUT=$((${OFFPEAKUSAGE_OUT}+${OUT}))
else
PEAKUSAGE_IN=$((${PEAKUSAGE_IN}+${IN}))
PEAKUSAGE_OUT=$((${PEAKUSAGE_OUT}+${OUT}))
fi

grep -v "${MAC}" ${2} > /tmp/db_$$.tmp
mv /tmp/db_$$.tmp ${2}
echo ${MAC},${PEAKUSAGE_IN},${PEAKUSAGE_OUT},${OFFPEAKUSAGE_IN},${OFFPEAKUSAGE_OUT},$(date "+%d-%m-%Y %H:%M") >> ${2}
fi
done
#Free some memory
rm -f /tmp/*_$$.tmp
unlock
;;
"publish" )

[ -z "${2}" ] && echo "ERROR : Missing argument 2" && exit 1
[ -z "${3}" ] && echo "ERROR : Missing argument 3" && exit 1
USERSFILE="/etc/dnsmasq.conf"
[ -f "${USERSFILE}" ] || USERSFILE="/tmp/dnsmasq.conf"
[ -z "${4}" ] || USERSFILE=${4}
[ -f "${USERSFILE}" ] || USERSFILE="/dev/null"

# first do some number crunching - rewrite the database so that it is sorted
lock
touch /tmp/sorted_$$.tmp
cat ${2} | while IFS=, read MAC PEAKUSAGE_IN PEAKUSAGE_OUT OFFPEAKUSAGE_IN OFFPEAKUSAGE_OUT LASTSEEN
do
echo ${PEAKUSAGE_IN},${PEAKUSAGE_OUT},${OFFPEAKUSAGE_IN},${OFFPEAKUSAGE_OUT},${MAC},${LASTSEEN} >> /tmp/sorted_$$.tmp
done
unlock

        # create HTML page
        echo "Traffic

Total Usage :

" >> ${3}
        echo "" >> ${3}
        echo "
UserPeak downloadPeak uploadOffpeak downloadOffpeak uploadLast seen
" >> ${3}
        echo "
This page was generated on `date`" 2>&1 >> ${3}
        echo "" >> ${3}

        #Free some memory
        rm -f /tmp/*_$$.tmp
        ;;

*)
echo "Usage : $0 {setup|update|publish} [options...]"
echo "Options : "
echo "   $0 setup"
echo "   $0 update database_file [offpeak]"
echo "   $0 publish database_file path_of_html_report [user_file]"
echo "Examples : "
echo "   $0 setup"
echo "   $0 update /tmp/usage.db offpeak"
echo "   $0 publish /tmp/usage.db /www/user/usage.htm /jffs/users.txt"
echo "Note : [user_file] is an optional file to match users with their MAC address"
echo "       Its format is : 00:MA:CA:DD:RE:SS,username , with one entry per line"
exit
;;
esac

How to extract 7zip files in ubuntu

First install 7zip package

sudo apt-get install p7zip  

( you will need universal repository to run the above command )


after installing

7z x my7Zzipfile




Script to check weather user is root or not

if [ "$UID" -ne "$ROOT_UID" ]
then
 echo "Must be root to run this script."
 exit $E_NOTROOT
fi

Script to check weather user is root or not

if [ "$UID" -ne "$ROOT_UID" ]
then
 echo "Must be root to run this script."
 exit $E_NOTROOT
fi