To grep multiple contents

egrep "foldername|foldername|foldername"

How to install RPM

How to install RPM
What is RPM?



Many Linux distributions use RPM as the default application management system. This means that when using RPM packages, it is quite easy to install applications to your favorite Linux distributions.

RPM is originally developed by Red Hat, but nowadays you can run into rpm in many other linux distributions (for example Fedora Core, CentOS, Mandriva or Yellow Dog Linux) and even on other operating systems (Novel Netware and IBM Aix).

RPM packaged software follows usually the following format:

(name)-(version)-(release).(arch).rpm

For example: httpd-2.23-2.i386.rpm

Also source codes can be downloaded in rpm packages. For example httpd-2.23-2.i386.src.rpm. RPM files with the noarch.rpm extension refer to files that don't depend on a computer's architecture.

Install RPM

Installing RPM package is very easy and straightforward:

* rpm -ivh package.rpm - installs package.rpm
* rpm -Uvh package.rpm - updates package.rpm
* rpm -qi package - displays (already installed ) information about application "package"
* rpm -qpi package.rpm - displays information about rpm-file
* rpm -qpl package.rpm - displays files included in package.rpm
* rpm -qa - lists all rpm packages installed to your distribution
* rpm --rebuilddb - rebuilds your rpm database

With these simple commands you can install rpm packages to your linux distribution!

Data base restore from old to new

1. Check whether the PHP and Apache configurations of /old and the new server.
/old/var/cpanel/cpanel.conf
/old/usr/local/apache/conf/
2. Recompile PHP and Apache to make so.
3. Run the script http://script.sherin.co.in/cpanel/restorefiles.sh
4. Copy the content in /old/var/lib/mysql to /var/lib mysql/ ---- (with same permisions and ownerships)
5. Copy the content of /old/home/ to /home/ ---- (with same permisions and ownerships)
6. Again run an upcp and recompile Apache and PHP.

disable open_base and safe_mode

Warning: curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when in safe_mode or an open_basedir is set in /home/brightla/public_html/directions.php on line 190


solution

1. log into his WHM and click Security Center under the Security section.
2.The 5th option down should be PHP open_basedir Tweak
3.From there you can disable it per account

Argument list too long

Argument list too long

Have you ever seen this very annoying error message? I bet you have!

I had to move little over 36k files in one directory to another box. Scp and both let me know there's too many files for them to handle. So what to do?

Each shell session has a pre-configured amount of storage with a hard limit. To check it you can type getconf ARG_MAX which will type whatever the max arg is in your box.

You can work around this easily wit tar. Just pre-build list of filenames and then pass the list to tar:


find . -iname '*.gif' > list.txt
tar czvf files.tar.gz --files-from list.txt


Sit back and enjoy the ride while box archives your files!

database repair

mysqldump: Got error: 145: Table './epidata_tikidb/tiki_searchindex' is
marked as crashed and should be repaired when using LOCK TABLES

solution:

myisamchk -crS /var/lib/mysql/database/*.MYI

HOW TO PREVENT DDOS ATTACKS

All web servers been connected to the Internet subjected to DoS (Denial of Service) or DDoS (Distrubuted Denial of Service) attacks in some kind or another, where hackers or attackers launch large amount connections consistently and persistently to the server, and in advanced stage, distributed from multiple IP addresses or sources, in the hope to bring down the server or use up all network bandwidth and system resources to deny web pages serving or website not responding to legitimate visitors.

You can detect the ddos using the following command

netstat -anp|grep tcp|awk '{print $5}'| cut -d : -f1|sort|uniq -c|sort -n

It will shows the number of connections from all IPs to the server.

There are plenty of ways to prevent, stop, fight and kill off DDoS attack, such as using firewall. A low cost, and probably free method is by using software based firewall or filtering service. (D)DoS-Deflate is a free open source Unix/Linux script by MediaLayer that automatically mitigate (D)DoS attacks. It claims to be the best, free, open source solution to protect servers against some of the most excruciating DDoS attacks.

(D)DoS-Deflate script basically monitors and tracks the IP addresses are sending and establishing large amount of TCP network connections such as mass emailing, DoS pings, HTTP requests) by using “netstat” command, which is the symptom of a denial of service attack. When it detects number of connections from a single node that exceeds certain preset limit, the script will automatically uses APF or IPTABLES to ban and block the IPs. Depending on the configuration, the banned IP addresses would be unbanned using APF or IPTABLES (only works on APF v 0.96 or better).

Installation and setup of (D)DOS-Deflate on the server is extremely easy. Simply login as root by open SSH secure shell access to the server, and run the the following commands one by one:

wget http://www.inetbase.com/scripts/ddos/install.sh
chmod 0700 install.sh
./install.sh

To uninstall the (D)DOS-Deflate, run the following commands one by one instead:

wget http://www.inetbase.com/scripts/ddos/uninstall.ddos
chmod 0700 uninstall.ddos
./uninstall.ddos

The configuration file for (D)DOS-Deflate is ddos.conf, and by default it will have the following values:

FREQ=1
NO_OF_CONNECTIONS=50
APF_BAN=1
KILL=1
EMAIL_TO=”root”
BAN_PERIOD=600

Users can change any of these settings to suit the different need or usage pattern of different servers. It’s also possible to whitelist and permanently unblock (never ban) IP addresses by listing them in /usr/local/ddos/ignore.ip.list file. If you plan to execute and run the script interactively, users can set KILL=0 so that any bad IPs detected are not banned