Nt1330 Unit 3 Network Analysis Paper

In order to access a UNIX system, and use it , you need to connect to the system. You can login:

Locally

Remotely

Login Types In general, there are two ways:

Command-line Login

GUI Login

Connecting Locally Connecting locally means, you are directly logging into the UNIX system. Network connectivity is not required.

You could login using the command-line or a GUI interface depending on the system configuration. Example of a GUI login interface on a CentOS machine

User enters "username" on this screen and hits enter.

User enters the password on this scree and hits "Sign In"

Example of a command line login interface (Unix System with no GUI interface) login as: mususer1 password: Note

You could have GUI interface installed, and force the command-line login as default.

Connecting Remotely To

External Commands Examples:

grep sort uniq

Listing all shell built-in commands - "help" command

Bash shell has a command called "help".

Just type "help", and hit enter.... it will display all the built-in commands.

How do you determine if a given command is an internal or external?

You can use one of the following:

which command type command

Searching all over the filesystem. (... not a preferred way. Instead use type or which)

We will use "type" command to determine about the "grep" and "cd" commands:

For external commands, the command displays the physical path.

For internal commands, the messages indicated that it is a builtin command.

$ type grep find is /usr/bin/grep

$

$ type cd cd is a shell builtin

$

We will use "which" command to determine about the "grep" and "cd" commands:

For external commands, the command displays the physical path.

For internal commands, there would be no response.

$ which grep

/bin/grep

$

$ which cd

$

Internal commands are much faster than external commands, as there is no process to spawn.

Well.... you don 't have an internal command for every external