Sunday, July 19, 2015

System Management

SYSTEM COMMANDS


uname -a
Display linux system information 


uname -r
Display kernel release information


last reboot
Show system reboot history


date
Show current date and time


cal
Show current month calendar4


whoami
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


df
Check filesytem storage

 
du
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
 

free      
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...


ctrl+alt+f1    
GUI (Graphical mode) to text mode i.e. CLI(Command Line Interface)


ctrl+alt+f7    
Text to graphic mode

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

 
kcontrol &      
Configure the kde enviroment


gnome-control-center      
Configure the gnome enviroment

 
switchdesk kde  
Set the default startup to kde


switchdesk gnome  
Set the default startup to gnome


up2date-config      
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
Sync the changed or changes take effect

 
top    
Will show the running process list
 

gnome-system-monitor  
Show the graphical mode of running process

 
uptime    
Show how long the system is running from last boot  and
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

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