Advanced Linux Shell Scripting for DevOps Engineers with User management

Advanced Linux Shell Scripting for DevOps Engineers with User management

#devops

  1. To add a user to the Linux system:

useradd devops

  1. setting user password:

passwd devops

  1. If we want to add a user by making a directory use the -m flag

    sudo useradd devops -m

    -d dir

    Set the user’s home directory to be dir.

    -s shell

    Set the user’s login shell to be shell.

    -u uid

    Set the user’s ID to be uid. Unless you know what you’re doing, omit this option and accept the default.

    -g group

    Set the user’s initial (default) group to group, which can either be a numeric group ID or a group name, and which must already exist.

    -G group1,group2,…

    Make the user a member of the additional, existing groups group1, group2, and so on.

    -m

    Copy all files from your system skeleton directory, /etc/skel, into the newly created home directory. The skeleton directory traditionally contains minimal (skeletal) versions of initialization files, like ~/.bash_profile, to get new users started If you prefer to copy from a different directory, add the -k option (-k your_preferred_directory).

  2. To check whether the user added or not if the user added where it should be present:

    sudo cat /etc/passwd

Adding group:

  1. sudo groupadd DevOps

  2. sudo groupadd QA

To check the Existing group:

1. sudo cat /etc/group

To add a user to the group

2. sudo gpasswd -a devops DevOps

  • -a for append

  • devops >> user

  • DevOps >> group

To create group

  1. sudo groupadd DevOps

Adding members(ubuntu centos) to the group (DevOps)

  • sudo gpasswd -M ubuntu, centos DevOps

  • -M flag for adding members

    Difference Between -a and -m flag

  • -a

    adding/appending the user to the group

    -m

    Adding a list of members to the group.

    man Command is useful in Linux it is a manual page where all the flag information also command information are provided within it.

To delete user and group:

  • userdel -d username

  • gpasswd -d groupname

To make group admin:

  • gpasswd -A

Three types of Linux Permission classes

  1. User

  2. group

  3. other

  4. Default permission is -rw-rw-r

    chmod 777 file.txt

    chmod 640 file.txt

for the user can get access from the file called sudoers file

cat /etc/sudoers

root ALL = (ALL:ALL) ALL

(ALL: ALL) >> user and group

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