Linux: Show all files modified in the last X days

> find -mtime -2 -print # where 2 is the number of days back

Adding swap space on CentOS

# login as root with
su -

# not '-' sign - important!

#allocate file: 20 GB = 20 * 1024 * 1024
dd if=/dev/zero of=/swapfile bs=1024 count=20971520

mkswap /swapfile

#set permissions:
chown root:root /swapfile
chmod 0600 /swapfile

#add immediately to OS
swapon /swapfile

# edit fstab for persistence:
vi /etc/fstab

# edit fstab by adding the following line at the end of the file:
/swapfile /swap swap defaults 0 0

# check if the swap is allocated
free -m

Increase number of open files per user

http://prefetch.net/blog/index.php/2009/07/31/increasing-the-number-of-available-file-descriptors-on-centos-and-fedora-linux-servers


$ ulimit -n
1024

$ cat /proc/sys/fs/file-max
366207

$ echo 512000 > /proc/sys/fs/file-max

$ cat /proc/sys/fs/file-max
512000

$ vi /etc/security/limits.conf

Now add a line after @student (the last user listed)

@username   -   nofile   70000


$ ulimit -n
8192

sudo: Sorry, you must have a tty to run sudo (SOLVED)

I found that running a cron job on CentOS I am getting an error:
sudo: Sorry, you must have a tty to run sudo
the script, running not as a root user was using a sudo command.

Some googling showed that this is what I need (run sudo visudo to edit the config file):
Defaults requiretty
Defaults:root !requiretty
Defaults:myusername !requiretty


Thus the default remains "requiretty" for everyone but for the named users.

Installing RabbitMQ on CentOS, Fedora and RHEL

# Login as root. Note "-" in su command, it is important to get proper shell definitions including the PATH
su -
....enter password


#verify OS version
cat /etc/*release*

# Download and enable EPEL
# for CentOS 5:

# rpm -Uvh http://download.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm

# for CentOS 6:
rpm -Uvh http://download.fedoraproject.org/pub/epel/6/i386/epel-release-6-7.noarch.rpm 


#Get & install Erlang
wget -O /etc/yum.repos.d/epel-erlang.repo http://repos.fedorapeople.org/repos/peter
/erlang/epel-erlang.repo

yum install erlang

# Get RabbitMQ signing key
rpm --import http://www.rabbitmq.com/rabbitmq-signing-key-public.asc

# check for the latest version at RabbitMQ web site: http://www.rabbitmq.com/install-rpm.html
rpm -Uvh http://www.rabbitmq.com/releases/rabbitmq-server/v2.8.4/rabbitmq-server-2.8.4-1.noarch.rpm

yum install rabbitmq-server-2.8.4-1.noarch.rpm

# if this command did not work take a look what you got in online repositories:
# http://repos.fedorapeople.org/repos/peter/erlang/
# probably your RPM does not exists there
# in this case you can try using older RPM
# if you decided to do that, do teh following:
vi /etc/yum.repos.d/epel-erlang.repo

#comment line
baseurl=http://repos.fedorapeople.org/repos/peter/erlang/epel-$releasever/$basearch/

# and replace it with
baseurl=http://repos.fedorapeople.org/repos/peter/erlang/epel-5/$basearch/

# next, comment line
baseurl=http://repos.fedorapeople.org/repos/peter/erlang/epel-$releasever/SRPMS

# and replace it with
baseurl=http://repos.fedorapeople.org/repos/peter/erlang/epel-5/SRPMS

# exit vi and try again running
# yum install rabbitmq-server-2.8.4-1.noarch.rpm

# Add RabbitMQ to list of services to be started on reboot
chkconfig rabbitmq-server on

# Add RabbitMQ management plugin:
/usr/sbin/rabbitmq-plugins enable rabbitmq_management sudo

# start RabbitMQ server

service rabbitmq-server start


# point your browser to  http://[your-rabbitmq-server]:55672
# enter user name / pwd: the defaults are guest / guest

Installing InfoBright Enterprise Edition (trial) on CentOS 5.7

# create license file on InfoBright web
# download the latest Infobright RPM

> rpm -i ib-installation-file.rpm

#copy license file to IB installation
> cp iblicense-yan123_yan123-89359130-IEE.lic /usr/local/infobright

# run the DB
/etc/init.d/mysqld-ib start

# make IB service running after reboot
> chkconfig --add /etc/init.d/mysqld-ib
> chkconfig mysqld-ib on

# change IB / MySQL root pwd
/usr/local/infobright-4.0.6-x86_64/bin/mysqladmin -u root password 'new-password'

# run mysql client and grant all privileges to a user
# from another host who comes with a certain password
mysql-ib -u root -p
[enter root password on prompt]
> GRANT ALL ON *.* TO 'myuser' IDENTIFIED BY 'some-user-password';

#add remote access and other permissions for 'root' too
> GRANT ALL ON *.* TO 'root' IDENTIFIED BY 'some-root-password';

Installing InfoBright database VM on Windows 7 with VMWare Player

1. Get Inforbright community edition (ICE) here: http://www.infobright.org/downloads/vm/ice32_352.zip
2. Get VMPlayer from vmware.com. Free registration required.
3. Run ice32.vmx file - WMPlayer opens.
4. In WMPlayer, "Virtual Machine->Power-Stop" - stop the VM and reconfigure to what you need: give it more CPUs and more RAM if needed. The default values are 1GB RAM and 1 CPU.
5. Restart VM
While rebooting you will see VM IP. Write it down.
Once VM goes up, point your web browser to that IP. You should see ICE32 web page with access credentials.
6. Login with
user: ice
password: infobright
7. Go to VMPlayer and run
mysql-ib -u root
8. Run in MySQL client the following command so you can access MySQL from another machine (e.g. from the machine where the VMWare is installed) -
grant all privileges on *.* to 'root'@'x.x.x.x' with grant option;
Note: The default install of InfoBright Database on VM is configured with user root with no password.

Now you should be able to connect to InfoBright running on your VMWare Palyer from an external machine.

9. Connection: The default port is 5029. You can check it out in my.cnf file (port=1234)

10. in VMPlayer (Ubuntu):
sudo /bin/bash
- change to root this way and edit /etc/my-ib.cnf if required.
For instance, add
max_heap_table_size = 1024M
under
[mysqld]
section

11. Restart Infobright DB:
sudo /etc/init.d/mysqld-ib stop
sudo /etc/init.d/mysqld-ib start