Contents
User and Groups
Adding user
Below command would add the user to linux servers. Here I am adding the user called “devopsdiggers”.
Command : sudo useradd <name of the user>
[ec2-user@ip-172-31-30-160 ~]$ sudo useradd devopsdiggers
Listing all the added users can be done in different ways. One is going to /etc/passwd where passwd file contains all the user details.Another way is using getent command. Bydefault there would be many users added to the list and we can see the added user (devopsdiggers) at very end.
Command : getent passwd
[ec2-user@ip-172-31-30-160 etc]$ getent passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin nobody:x:65534:65534:Kernel Overflow User:/:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin systemd-coredump:x:999:997:systemd Core Dumper:/:/sbin/nologin systemd-resolve:x:193:193:systemd Resolver:/:/sbin/nologin tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin polkitd:x:998:996:User for polkitd:/:/sbin/nologin unbound:x:997:995:Unbound DNS resolver:/etc/unbound:/sbin/nologin sssd:x:996:993:User for sssd:/:/sbin/nologin sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin chrony:x:995:992::/var/lib/chrony:/sbin/nologin rngd:x:994:991:Random Number Generator Daemon:/var/lib/rngd:/sbin/nologin ec2-user:x:1000:1000:Cloud User:/home/ec2-user:/bin/bash devopsdiggers:x:1001:1001::/home/devopsdiggers:/bin/bash
Creating Password for User
To be able to login with the created user name, password must need to be created.
Command: sudo passwd <name of the user>
When it asks for the password , give the strong password and also retype it when it asks for retype.
[ec2-user@ip-172-31-30-160 ~]$ sudo passwd devopsdiggers Changing password for user devopsdiggers. New password: Retype new password: passwd: all authentication tokens updated successfully.
Deleting User
Below command will delete the user.
Command : sudo userdel <name of the user>
[ec2-user@ip-172-31-30-160 ~]$ sudo userdel devopsdiggers
Above command only deletes the user but it does not delete the user home directory. If you want to delete the entire user account please add “-r” flag to the userdel command.
Command : sudo userdel -r <name of the user>
Creating Groups
To create groups in linux, groupadd command would help.Here the adding group name is “devops“.
Command : sudo groupadd <name of the group>
[ec2-user@ip-172-31-30-160 ~]$ sudo groupadd devops
To list the all the groups use getent command or open the group file in etc directory.
Command : getent group
[ec2-user@ip-172-31-30-160 etc]$ getent group root:x:0: bin:x:1: daemon:x:2: sys:x:3: adm:x:4:ec2-user tty:x:5: disk:x:6: lp:x:7: mem:x:8: kmem:x:9: wheel:x:10: cdrom:x:11: mail:x:12: man:x:15: dialout:x:18: floppy:x:19: games:x:20: tape:x:33: video:x:39: ftp:x:50: lock:x:54: audio:x:63: users:x:100: nobody:x:65534: dbus:x:81: utmp:x:22: utempter:x:35: input:x:999: kvm:x:36: render:x:998: systemd-journal:x:190:ec2-user systemd-coredump:x:997: systemd-resolve:x:193: tss:x:59: polkitd:x:996: unbound:x:995: ssh_keys:x:994: sssd:x:993: sshd:x:74: chrony:x:992: rngd:x:991: ec2-user:x:1000: devopsdiggers:x:1001: devops:x:1002:
Deleting Group
Groups can be deleted by using “groupdel” command.
Command: sudo groupdel <name of the group>
[ec2-user@ip-172-31-30-160 etc]$ sudo groupdel devops
Adding User to Group
Adding an existing users to an existing groups can be done in different ways.
Command: sudo usermod -a -G <name of the group> <name of the user>
[ec2-user@ip-172-31-30-160 ~]$ sudo usermod -a -G devops devopsdiggers
To validate the groups which user belongs to.
Command : id <name of the user>
[ec2-user@ip-172-31-30-160 ~]$ id devopsdiggers uid=1001(devopsdiggers) gid=1001(devopsdiggers) groups=1001(devopsdiggers),1002(devops)
Removing User From Group
Removing the user from the group can be done by using “gpasswd” command.
Command : sudo gpasswd -d <name of the user> <name of the group>
[ec2-user@ip-172-31-30-160 ~]$ sudo gpasswd -d devopsdiggers devops Removing user devopsdiggers from group devops
