Run levels in linux shell

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Basic Linux Tutorial

Introduction – What is it? Why to learn? Linux installation directory structures Boot process Run levels in Linux Desktop Environments Different shells BASH Internal and External Commands Basic Linux Commands Important files and directories in Linux Environmental and Shell Variables Command history in Linux Character classes in Linux Text editors vim nano Searching files Creating new files Viewing File Contents File commands File permissions and ownership WildCards (Globbing) in files File compression Directory commands xargs command in Linux Comparing files Searching patterns using grep command Translating the characters using tr command Extracting data using cut command Stream editing using sed command Data extraction and reporting using awk command Sorting the file or string input uniq command in Linux Difference between grep, tr, cut, sed and awk commands Hardware commands Hard disk and memory space commands Working with Processes Managing Jobs Working with cron jobs Service command in Linux Network commands Managing Users and Groups Other Popular commands Standard streams and Redirection Pipes Package Managers in Linux

Run levels in linux shell

A Linux system can be in specific run level. Linux system usually can have 7 run level (0-6).

0 run level is used to shut down the system.
6 run level is used to reboot the system.

Run levels 1 to 5 are used to start the system in single user or multi user mode and with or without networking. We can use below command to check run level of the system.

 
$ runlevel
$ who -r

To know which processes will start in any of the run level, you can use below command.

 
$ chkconfig

You can use below command to shut down the system.

 
$ init 0

You can use below command to restart the system.

 
$ init 6

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