Pario TechnoBlob » sed

Replace specific HTML tags using sed and regular expression

Hans-Henry Jakobsen — Fri, 12 Jun 2009 13:33:22 +0000

In this post I would like to replace all HTML tags in a HTML file with a tag.

# sed -e 's/]*>//g' filename.html > newfile.html

And if you would like to remove the tag altogether

# sed -e 's/]*>//g' filename.html > newfile.html

To remove all HTML tags in a file

# sed -e 's/<[^>]*>//g' filename.html > newfile.html

The result file newfile.html is now without any < HTML tags >.

IP address change notifier script

Hans-Henry Jakobsen — Wed, 21 Jan 2009 12:57:16 +0000

This is a simple bash script that is run by crontab every 5 minutes on a linux box.
It e-mails me the new address when a change of IP address is detected.

The script (ipchangemail.sh)

#!/bin/bash # Check if IP-address has changed. If a change has occured, mail me the new address # Add the following line to crontab if you would like it to be run every 5 minutes: # */5 * * * * ./ipchangemail.sh # The network interface I want to monitor NET_INTERFACE=eth0 # File to keep the latest IP address IP_FILE=myip.txt # Mail to this address when a change occur MAILTO=mail@example.com # Read the previous IP address from file source $IP_FILE CURRENT_IP=`/sbin/ifconfig $NET_INTERFACE | sed -n "/inet addr:.*255.255.25[0-5].[0-9]/{s/.*inet addr://; s/ .*//; p}"` if [ "$CURRENT_IP" != "$OLD_IP" ] then # Send email about address change `echo "New IP address detected: $CURRENT_IP" | mail -s "New IP address" $MAILTO` # Write new address to file `echo "OLD_IP=$CURRENT_IP" > $IP_FILE` fi

The script can be downloaded here.

Apache web connections pr hour

Hans-Henry Jakobsen — Thu, 21 Feb 2008 22:26:15 +0000

This is a bash oneliner to show Apache web connections pr hour. It lists up the IPs that has accessed your webserver and the amount og accesses.

# cat /var/log/apache2/access_log_pario.no | grep "21/Jan/2008:.." | awk {' print $4":"$1 '} | sed 's/\[//g' | awk -F : {' print $1":"$2"\t\t"$5 '} | sort | uniq -c

Example output

37 21/Jan/2008:00 192.168.0.10

This shows that I had 37 hits from 00:00 – 01:00 in 20th February 2008.

Strip the kernel to contain only needed modules

Hans-Henry Jakobsen — Tue, 04 Dec 2007 14:38:45 +0000

This is a great page with som nice bash scripts describing how to remove unwanted modules from your kernel.

Using TCP Wrappers to deny daemon access in specified hours

Hans-Henry Jakobsen — Thu, 25 Oct 2007 18:30:22 +0000

By doing the following you can deny certain daemons to be available in specified hours by using hosts.allow and hosts.deny.

In my example I will be using the vsftpd daemon by adding

tcp_wrapper=YES

in /etc/vsftpd.conf.

Make sure that your private network has access all the time by adding this in /etc/hosts.allow

vsftpd: 192.168.0.

Enables access to the whole subnet.

Next you create a /etc/cron.d/vsftpd file

0 16 * * 1-5 root perl -i -p -e s/innhold//ig /etc/hosts.deny 0 8 * * 1-5 root echo "vsfdpt:ALL >> /etc/hosts.deny

Reload the cron daemon and you’re good to go.

The above example will deny all addresses, except those specified in hosts.allow, between 08:00 and 16:00 Monday to Friday and clear the block at other times.