uname -a

Display linux system information 



uname -r

Display kernel release information



last reboot

Show system reboot history




Show current date and time




Show current month calendar4




Who you are logged in as 



finger user

Display information about user



cat /proc/cpuinfo

Show cpu info



cat /proc/meminfo 

Show memory information


man command

Show manual for command




Check filesytem storage



Check subdirectories


df -h            

Shows file size which is user readable



du --max-depth=1 -h  

Check subdirectories by one level down


whereis app

Show possible location of app



which app

Show which app will be run by default



To check ram & swap partition  usuage



free -g

To see usuage in gigabytes



dd if=/dev/zero of=/swapfile bs=1024 count=1024


dd to create a storage file

if=/dev/zero : Read from /dev/zero file.  /dev/zero is a special file in that provides as many null characters to build storage file called /swapfile.
of=/swapfile : Read from /dev/zero write storage file to /swapfile.
bs=1024 : Read and write 1024 BYTES bytes at a time.
count=1024 : Copy only 1024 BLOCKS input blocks.



mkswap /swapfile 

To setup a linux swap area in a file.



swapon /swapfile
Enable the swap file.



swapoff /swapfile


Disable the swap file.

Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks. For example, the block size of a 64 MB swap file is 65536. 



lvextend -l +100  /logical/volume00

Extend the logical volume 00 from blank space i.e. 0mb to volume 00 with 100 mb...




GUI (Graphical mode) to text mode i.e. CLI(Command Line Interface)




Text to graphic mode


Types Of Boot Loader
grub  grand unified boot loader
lilo linux bootloader


kcontrol &      

Configure the kde enviroment




Configure the gnome enviroment


switchdesk kde  

Set the default startup to kde



switchdesk gnome  

Set the default startup to gnome




Configure the red hat for update



mount /dev/sda1  /tmpdir         mount the sda1 file in tmpdir directory

mount /dev/sda0 /tmpdir          mount the sda0 file in tmpdir directory

unmount  /tmpdir/boot   unmount boot directory

unmount /tmpdir                 unmunt tmpdir directory



Sync the changed or changes take effect



Will show the running process list



Show the graphical mode of running process




  • Show how long the system is running from last boot 
  • load average of first no show the the total load in last one minute 
  • load average of second no show the the total load in last five minute
  • load average of third no show the the total load in last fifteen minute