4. Redhat Linux : RHCE 6

4. Redhat Linux : RHCE 6

 

Packages Installation 

RPM (Redhat Packet Management)
------------------------------
* do not resolve dependencies
* installation package should be in the pwd

YUM (Yellowdog Update Management)
---------------------------------
* resolve dependencies itself
* install from the network
* configure yum:
 Install vsftp and createrepo
 Copy packages to /var/ftp/pub/anyname(if you want to access from other clients)
 Run createrepo command 'createrepo /var/ftp/pub/anyname'
 Create /etc/yum.repos.d/packages.repo and include:
  [server]
  name=packages.repo
  baseurl=ftp://192.168.x.x/pub/anyname
  enabled=1
  gpgcheck=0
 Restart vsftp using 'service vsftp restart'

vsftpd:
------
* very secure ftp
* used to network install using yum
      Job Scheduling
      --------------
3 Types:
-------
* cron  : periodically
* anacron : different periods
* at  : one time

fields in crontab:
-----------------
  minutes  hours days of month month Days of week 
eg: */1  * *  * *  echo "Hello" > /dev/pts/4
eg: 06  15 26  * *  sh script.sh > /root/cron_out

* all the users can schedule the crone and at jobs by default
* to deny permission for any user add user in /etc/cron.deny
* to deny permission for any user add user in /etc/at.deny

Updating Kernel:
---------------
* rpm -ivh kernel.rpm
* vim /etc/grub.conf and edit as
 default=1
* yum update

/*
Commands for the day:
--------------------

* rpm -ivh packageName.version.release.arch.rpm  : installs the package
* rpm -q package      : queries the package
* rpm -qd package     : document of the package
* rpm -e package     : removes the package
* yum install package     : to install packages
* yum remove package     : removes the package
* yum info package     : gives info about the package
* yum update      : update the system
* crontab -e      : add cron jobs
* crontab -e -u username    : add cron jobs for any user
* crontab -l      : list all cron jobs
* crontab -r      : remove cron jobs
* at now      : schedule at current time
* at 23:59      : schedule at user defined time
* at -l       : list all scheduled jobs
* at -r       : remove all scheduled 'at' jobs
* createrepo /var/ftp/pub/anyname   : create local installation repository
* service vsftp restart     : restart vsftp service
*