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What is a Process

An instance of a program is called a Process.

Any command that you give to your  Linux machine starts a new process.

It is possible that for the same program we have multiple processes.

Types of Processes

• Foreground Processes

• Background Processes

Processes in action

Process  running on system are actions running on system.

Jobs are specific to a user for that given shell where it is been run.

You can check the number of processes running by using command,

 ps aux

And also get the count of total processes by using command,

 ps aux | wc

A job run by user or root is specific to his profile and for that given shell.

It has nothing to do with system processes running.

Example,

You can write a job specific to shell, like,

 dd if=/dev/zero of=/dev/null

This job does nothing and shows nothing.

Input file - /dev/zero

Output file - /dev/null

Every command that we start from a shell is considered a shell job.

If we type command ls

So, this is shell job.

 They start and stop immediately since they have done their work.

 Hence it is important to know the difference between a job and process.

If we buy RHEL 7 the system by default will be connected to Red Hat Network (RHN).

All packages and updates will be installed from RHN. So RHN will be our main source and repository.

Since we have not purchased the official licensed version of Red Hat - and using a free version. It is by default not connected to any repository.

To create our own repository we need to update information in the system.

For that we need to go to directory,

 cd /etc/yum.repos.d

Create a file with extension .repo

 vim myrepo.repo

On this file we need three things,

1. name - Name or a Label for the repository. We may give any name for repository.
2. baseurl - The Base URL gives the location of repository to be used/picked.
1. It can be file:// if local directory
2. It can be http:// or ftp://
3. gpgcheck- This is for file integrity checking. Set as 0 if you do not want integrity check. For live environment it is important to set gpgcheck keys carefully. Else for this local setup and testing 0 is ok to continue.

Example now,

 name=myRepo

 baseurl=file:///dump/repo/packages

 gpgcheck=0

Save and exit.

To verify we can do commands,

1. yum repolist to give information about repo being used.
2. Or, yum search ftp to search and verify output. Where ftp is package name as example.