리눅스 통신
** 리눅스 통신
` PING
- ping
- Analyzing network and host connections
- Tracking network performance and managing it
- Testing hardware and software issues
` FTP
- FTP is File Transfer Protocol.
- ftp
- Logging in and establishing a connection with a remote host.
- Upload and download files.
- Navigating through directories.
- Browsing contents of the directories.
- dir : Display files in the current directory remote computer
- cd "dirname" : Change directory to "dirname" on remote computer
- put file : upload 'file' from local to remote computer
- get file : Download 'file' from remote to local computer
- quit : Logout
` Telnet
- telnet
- Connect to a remote Linux computer.
- Run programs remotely and conduct administration.
- Similar to the Remote Desktop found in Windows Machine.
` SSH
- SSH username@ip-address or hostname
- Securely connect to a remote computer
- Compared to Telnet, SSH is more secure
`` Summary
- Communication between Linux/UNIX and other different computers, networks and remote users is possible.
- The ping command checks whether the connection with a hostname or IP-address is working or not. Run 'ping IP address or Hostname' on the terminal.
- FTP is preferred protocol for sending and receiving large files. You can establish a FTP connection with a remote host and then use commands for uploading, downloading files, checking file and browsing them.
- Telnet utility helps you to connect to a remote Linux computer and work on it.
- SSH is a replacement for Telnet and is used by system administrators to control remote Linux servers.
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`` Environment Variables
` Platform = Operating System + Processor
` Variable ?
- Location for storing a value
- Referred to with its symbolic name
- The value stored can be displayed, deleted, edited and re-saved
` Environment Variables ?
- Dynamic values
- Exist in every operating system
- Can be created, edited, saved and deleted
- Gives information about the system behavior
- Change the way software/programs behave
- PATH : This variable contains a colon(:)-separated list of directories in which your system looks for executable files.
- USER : The username
- HOME : Default path to the user's home directory
- EDITOR : Path to the program which edits the content of files
- UID : User's unique ID
- TERM : Default terminal emulator
- SHELL : Shell being used by the user
- ENV : displays all the environment variables
` Accessing Variable values
- echo $VARIABLE
` Creating New Variables
- VARIABLENAME = variablevalue
` Deleting Variables
- unset
`` Summary
- Environment variables govern behavior of programs in your Operating system.
- echo $VARIABLE : To display value of a variable
- env : Displays all environment variables
- VARIABLE_NAME = variable_value : Create a new variable
- unset
- export Variable = value : To set value of an environment variable