linux in browser - 20 Linux Commands for System Administrator

20 Linux Commands for System Administrator

Geek Flare Blog post is sponsored by Netsparker Web Application Security Scanner.

New to Linux?

Get familiar with some of the basic yet essential commands which you will have to use regularly as a Linux administrator.

Find kernel version

uname -r

Display file size in human readable format (e.g. KB, MB etc.,)?

ls -lh

What is the Linux process priority levels?

19 (lowest) to –20 (highest)

How many characters can have filename?


How to Shutdown the system after 10 minutes?

shutdown -h +10

What is the command to rebuild the initrd image ?


How to gather sar output specific time for memory?

sar -s 02:00:00 -e 03:00:00 -r

What file lists the DNS servers a UNIX host uses?


What’s the default filesystem type on Redhat Linux 5?


What command can you use to review boot messages?


Which file to set a kernel parameter on a Linux machine?


What is the configuration file for ports?


How to create a swap file in a data partition?

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

How to delete files older than 7days?

find /path/to/files* -mtime +7 -exec rm {} ;

Check disk usage in human readable and sort by size?

du -sh * | sort

How to list the password and its related details an user?

chage -l username

How to set account expiry date for a user?

chage -E "2012-06-31" raja

How to disable password aging for a user account?

chage -m 0 -M 99999 -I -1 -E -1 madhu

How to check memory map of a given process id 5264?

pmap 5264

How to verify crontab entry for a specific user

crontab -u username -l

I hope this helps.

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