Script to simulate multiple DHCP clients

#!/bin/sh

#simulate 255 IPhones requesting DHCP

 

 

# Apple OUI = D8:96:95

BASE="d8:96:95:08:96"

FROM=$1

shift

TO=$2

 

if [ -e $FROM ]; then FROM=1; fi

if [ -e $TO ]; then TO=1; fi

 

for i in `seq $FROM $TO`

do

    LSB=`echo "obase=16; $i" | bc`

    MAC="$BASE:$LSB"

    HNAME="`uname -n`-fakehost-$i"

    #CMD="$HOME/bin/dhtest -m $MAC -V -i eth1 -h '$HNAME'"

    CMD="$HOME/bin/dhtest -m $MAC -i eth1 -h '$HNAME'"

    echo $CMD

    $CMD

    sleep 1

done

Another way, the program dhtest (source code) can be download from  https://github.com/saravana815/dhtest.  

For example:

 

git clone https://github.com/saravana815/dhtest

cd dhtest

make

Daily backup of local git changes

While working on a ticket and not ready to commit, it's a good idea to backup all of our changes to an archive file.

The following script does all that and executed daily by cronjob automatically.

1. create a file, say "backup" in /etc/cron.daily
2. Type the following (change '<yourhome directory>' to your own login name and <git location> to the git directory where source codes are located):

backing up changed files to tarball

#!/bin/sh pushd <your source-code location> LIST=`git status --porcelain | sed -n -e '/^ [D|M]/p' | sed -e 's/^ [D|M] //'` backupname=`git branch | sed -n -e "/^* /p" | sed  -e 's/** //'` backupname=$backupname-`date "+%s"`.backup.tar.bz2 dest='<your home directory>' if [ ! -d "$dest" ] then     mkdir -p $dest fi tar jcvf $dest/$backupname $LIST > /dev/null

Make the file executable:

chmod +x /etc/cron.daily/backup