LINUX Command Line (SHELL)

 

Let's take a look at the concept:
- Most of user now days use computer with GUI to interact with the program.
- In the world of software development & system administration the program don’t have/ don’t need them (GUI).
- Like the server program, it’s placed in a data center and without monitor. One way we interact with the server or program that don’t have a GUI is through command line.
- Command line is text based interface where we  type command and get direct text input and output to screen/files/other program.

- The environment we use is SHELL/command line interpreter, many shell variation out there.
- The SHELL is default user interface to LINUX. On the GUI based you could use the TERMINAL.
- Start in 1971 by Thompson Shell for UNIX.
- Common Linux use BASH SHELL (Bourne Again Shell).



When the shell started its showed prompt by default.
The Prompt example:
    farihin@farihin-server:~$
    root@farihin-server:~#
The promp give you some information, like the example above:
farihin/root = username currently used
farihin-server = hostname/computer name
$ = using shell as normal user
# = using shell as super user (root)
~ = showing home/parent directory
root folder and root user is different thing.

Basic shell command:

Command	Description
cat [filename]	Display file’s contents to the standard output device
	(usually your monitor).
cd /directorypath	Change to directory.
chmod [options] mode filename	Change a file’s permissions.
chown [options] filename	Change who owns a file.
clear	Clear a command line screen/window for a fresh start.
cp [options] source destination	Copy files and directories.
date [options]	Display or set the system date and time.
df [options]	Display used and available disk space.
du [options]	Show how much space each file takes up.
file [options] filename	Determine what type of data is within a file.
find [pathname] [expression]	Search for files matching a provided pattern.
grep [options] pattern [filesname]	Search files or output for a particular pattern.
kill [options] pid	Stop a process. If the process refuses to stop, use kill -9 pid.
less [options] [filename]	View the contents of a file one page at a time.
ln [options] source [destination]	Create a shortcut.
locate filename	Search a copy of your filesystem for the specified
	filename.
lpr [options]	Send a print job.
ls [options]	List directory contents.
man [command]	Display the help information for the specified command.
mkdir [options] directory	Create a new directory.
mv [options] source destination	Rename or move file(s) or directories.
passwd [name [password]]	Change the password or allow (for the system administrator) to
	change any password.
ps [options]	Display a snapshot of the currently running processes.
pwd	Display the pathname for the current directory.
rm [options] directory	Remove (delete) file(s) and/or directories.
rmdir [options] directory	Delete empty directories.
ssh [options] user@machine	Remotely log in to another Linux machine, over the network.
	Leave an ssh session by typing exit.
su [options] [user [arguments]]	Switch to another user account.
tail [options] [filename]	Display the last n lines of a file (the default is 10).
tar [options] filename	Store and extract files from a tarfile (.tar) or tarball (.tar.gz or .tgz).
top	Displays the resources being used on your system. Press q to Exit
touch filename	Create an empty file with the specified name.
who [options]	Display who is logged on.