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Disk Free (DF) Utility in Linux System

Disk Free (DF) Utility

# df --- Show the used and available disk space 

# free –m --- Show free and used RAM in megabyte

#free –g --- Show free and used RAM in giga bytes 

# bg --- To send a process to back ground

# fg --- To run a stopped process in the back ground

# top --- Details of all active process 

# ps --- Give the status of a process running for a user

# ps <PID_number> --- Give the status of a particular process 

# pidof  <process_name> --- Give the process ID (PID) of a process

# kill <PID_number> --- kill a process

# nice --- start a process with a given priority

# renice --- Change priority of an already running process

# df --- give free hard disk of your system

# free --- Tell the free RAM of your system

Kill Utility on Linux

                                                                              KILL Utility

# This utility is used to terminate the running process

# kill <PID_number> --- Kill the specific process

# Linux can process a lot of process at a time

# Nicenes has the value between -20 to 19

# The lower the niceness index, higher would be the priority, given to the task

# Default value of all the process is 0

# nice –n “nice_value” process name

# renice “nice_value” –p <PID_number>

# To prioritize the system we use nice value.

# The priority index of a process is called nice in linux. Its defaults valu is o and it can vary between 20 to -19

Miscillanious short note on Linux. Part-3

# karnel is the nucleus of the operating system and it communicate between hardware and software .

# Shell is a interprets use m which interprets user command through CLI like terminal.

# The bourne shell and the c shell are the most used shells in Linux

# Perl is a programming language specially used for script editing.

# Alt +Ctrl +F1 --- Number one virtual terminal.

# Alt +Ctrl +F2 --- Number two virtual terminal.

# Total 6 virtual terminal

# tty1 --- virtual terminal number one

# Alt + Ctrl + F7 --- Main terminal

# Arrow up --- Scroll up in history and enter to execute

# Arrow down --- Scroll down in history and enter to execue

# Ctrl + D --- Logout from the terminal

# Ctrl + Alt + del --- Reboot the system

# Every user has default umask value

# Depending on the umask value of the user in linux, default permission is set to file and directory .

# User cannot use the file and directory by the default permission.

# Default permission of file and directory of the user is 0664 and 0775

Short note about VI Editor in linux

VI Editor

# vi <file_name> --- It will create new file and open in command mode.

#After opening the vi in the command mode

   #i--- insert a cursor
   #a--- write after cursor
   #A--- write at the end of the line
   #ESC --- Terminate the insert mode
   #u--- Undo last change
   #U--- Undo all change to the entire line
   #O – Open a new file
   #dd--- delete a line
   #3dd--- Delete 3 line
   #D--- Delete contents of line after the courser
   #c--- Delete contents of line after the courser and inset new text
   #dw--- Delete word
   #4dw--- Delete 4 words
   #Cw--- change word
   #x--- Delete character at cursor
   #r--- replace cursor
   #R--- Overwrite charecter from the cursor on ward.
   #s--- Substitute one character under cursor continue to insert
   #S--- Substitute entire line and begin to insert at beginning at the line.
   #~ --- Change case of individual character.

Save and closing the file from vi editor

Shift +zz --- Save the file and quit
:w --- Save the file but keep it open
:q --- Quit without saving
:wq --- Save the file and quit
:x --- Save the file and quite