1. To find OS-Version
cat /etc/redhat-release
2. To Find the System Configuration
Lscpu
3. To check disk space
df [-h|-i|-H] [<directory>]
4. To check installed shell
5. To run a script file in debug mode to see all running commands in console
6. To list all users
7. To add user
When we add a new user in Linux with useradd command it gets created in locked state and to unlock that user account, we need to set a password for that account with passwd command.
passwd <username>
8. To view user details
9. To view all users, group files
vi /etc/passwd
vi /etc/group
getent group
getent passwd
10. To remove a user account including home directory
Note: In case unable to delete a user using userdel will give error that “user <username> is currently used by process <pid>” then execute below commands and try userdel again:
su – <username>
kill -9 -1
exit
11. To change owner user/group of a directory
12. To list/qurey all libraries in Linux
13. To extract .tar.gz files
14. To check running application on particular port
15. To Find any file
16. To uninstall packages using GUI
17. Permanent configuration of java path in Linux
Configure PATH environment variable in ~/.bash_profile file for permanent configuration of java as following:
Linux - Points to Remember:
1. Avoid using the underscore (_) character in machine
names. Internet standards dictate that domain names conform to the host name
requirements described in Internet Official Protocol Standards RFC 952 and RFC
1123. Domain names must contain only letters (upper or lower case) and digits.
Domain names can also contain dash characters ( - ) as long as the dashes are
not on the ends of the name. Underscore characters ( _ ) are not supported in
the host name.
2. Linux File Permissions:
Read = 4
Write = 2
Execute = 1
Note: If a user wants to delete
file/folder having all rights then user should also have all rights in its
parent folder.
