www.usoft.it
my ( memory && esperience)

EPEL (Extra Packages for Enterprise Linux) is a volunteer-based community effort from the Fedora project to create a repository of high-quality add-on packages that complement the Fedora-based Red Hat Enterprise Linux (RHEL) and its compatible spinoffs, such as CentOS and Scientific Linux.

As part of the Fedora packaging community, EPEL packages are 100% free/libre open source software (FLOSS).

How can I install the packages from the EPEL software repository?

su -c ‘rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-3.noarch.rpm’
…
su -c ‘yum install foo’

The best method for teach an argument in this work is an practice example then we will start from here.

In the my server I have thousand of good user and one terrible user usernkey , I won’t what this user occupy all space in my server with his trash download therefore i will use the quote to deny this.

In this example I use CENTOS 5.4 because for this example REDHAD is expensive but the procedures are the same.

1. FIRST STEP

I must verify if my kernel was compiled with  the support for the quota ( my kernel version is 2.6.18-164.el5) with this command [ grep 'CONFIG_QUOTA' /boot/config-2.6.18-164.el5 ] .

If  I see

CONFIG_QUOTA=y
CONFIG_QUOTACTL=y

I don’t have a problem but if I see this

CONFIG_QUOTA=n
CONFIG_QUOTACTL=n

I have a problem because this kernel doesn’t have the support for the quota and I must recompile it with this support.

The standard kernel release of REDHAT and CENTOS have the support for the quota enabled therefore you don’t have this problem if you use the standard kernel

2. SECOND STEP

I must mount the filesystem which I want apply the quota with the option usrquota and grpquota, writing the option in the fstab

example :

/dev/hdc1               /home                   ext3    defaults,usrquota,grpquota        0 0

for apply this option use [ mount -o remount /home ]

3. THIRD STEP

For the quota the filesytem necessity of 2 files aquota.group aquota.user but you mustn’t create these file manualy , you must use the command [ quotacheck -cugm /home ] , now you will see this two new file in the path /home

4. FOURTH STEP

With the command  [ edquota -u usernkey ]  I can configure the quota on my system for the user usernkey.

There are two type of quota, block quota and inode quota:

- the block quota refer to the effectly occupated space ( 1k blocks is the unit )

- the inode quota refer to the number of inode in the filesystem for that user

for all the type of quota we can set two type of limits soft limit and hard limit , if  we pass the softlimit we will see in the prompt the warning message but if we will pass the hard limit we will see an error an the dimension of the file will be truncked to the value of the hard limit

example :

Disk quotas for user usernkey (uid 500):
Filesystem                   blocks          soft             hard         inodes     soft     hard
/dev/hdc1                     344          1000          2000        137          0        0

5. FIFTH STEP

You must active the quota with the command [ quotaon /home ]

6. SIXTH STEP

The end of the configuration is always the test and this is not different

log the in the system with the user usernkey

go in to the usernkey home

create one file with the dimension set in the soft limit with this command

[ dd if=/dev/zero of=/home/usernkey/out bs=1k count 1500] in the console will see one warning message

if I will use the command

[ dd if=/dev/zero of=/home/usernkey/out bs=1k count 10000] in the console will see one error message and the file was trunked at 2 Mbyte