lsblk Linux Command | Detail of lsblk Linux Command | lsblk details

This post is divided into three parts.

•  Default command and default output of lsbkl linux command 
• Options for lsblk Linux command 
• Available columns for output of lsblk Linux command

Default command and Default out put of lsblk linux command:

•  [appsdba@reyaz Desktop]$ lsblk 

Default output of lsblk

Options for lsblk Linux command:

Options:

 -a,                          --all                        print all devices

 -b,                         --bytes                    print SIZE in bytes rather than in human readable format

 -d,                         --nodeps                 don't print slaves or holders

 -D,                         --discard                print discard capabilities

 -e,                         --exclude <list>      exclude devices by major number (default: RAM disks)

 -I,                           --include <list>     show only devices with specified major numbers

 -f,                          --fs                         output info about filesystems

 -h,                         --help                      usage information (this)

 -i,                           --ascii                    use ascii characters only

 -m,                        --perms                  output info about permissions

 -l,                           --list                      use list format output

 -n,                         --noheadings          don't print headings

 -o,                         --output <list>        output columns

 -p,                         --paths                    print complate device path

 -P,                         --pairs                     use key="value" output format

 -r,                          --raw                      use raw output format

 -s,                          --inverse               inverse dependencies

 -t,                          --topology             output info about topology

 -S,                          --scsi                    output info about SCSI devices

 -h,                         --help                    display this help and exit

 -V,                         --version               output version information and exit

Available columns for output of lsblk Linux command:

NAME	device name
KNAME	internal kernel device name
MAJ:MIN	major:minor device number
FSTYPE	filesystem type
MOUNTPOINT	where the device is mounted
LABEL	filesystem LABEL
UUID	filesystem UUID
PARTLABEL	partition LABEL
PARTUUID	partition UUID
RA	read-ahead of the device
RO	read-only device
RM	removable device
MODEL	device identifier
SERIAL	disk serial number
SIZE	size of the device
STATE	state of the device
OWNER	user name
GROUP	group name
MODE	device node permissions
ALIGNMENT	alignment offset
MIN-IO	minimum I/O size
OPT-IO	optimal I/O size
PHY-SEC	physical sector size
LOG-SEC	logical sector size
ROTA	rotational device
SCHED	I/O scheduler name
RQ-SIZE	request queue size
TYPE	device type
DISC-ALN	discard alignment offset
DISC-GRAN	discard granularity
DISC-MAX	discard max bytes
DISC-ZERO	discard zeroes data
WSAME	write same max bytes
WWN	unique storage identifier
RAND	adds randomness
PKNAME	internal parent kernel device name
HCTL	Host:Channel:Target:Lun for SCSI
TRAN	device transport type
REV	device revision
VENDOR	device vendor

For more details use lsblk -help

 

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rhcsa | user and group management

Objective of this part:

• What is a group? 
• Group management 
• User management 
• How to assign password to users? 
• How to force user to change password on next logon?

rhcsa | user and group management
What is group?
 

We can say a group is a collection of users. Users are collected together with a name and the name is group. Group is actually for giving some specific permission.

Let us consider a group name “dba” and in this group we have some users like oracle, user1, user2 etc.

This group dba can give some permission to users and this is the concept of group. Hope you clear. If anything else then please feel free to comment below

 

rhcsa | user and group management
Group Management

          We have a group file and location of this group file is following below…
          [root@reyaz ~]# cd /etc/
          [root@reyaz etc]# ls -l group
          -rw-rw-r-- 1 appsdba dba 1008 Feb 11 12:02 group

To open this group file and to see all group in this file please use this below command

[root@reyaz etc]# cat group

From above picture we see a group named “dba” and there are 2 user “appsdba” and “oracle”. Please note that there is a number 1002 and it a group ID of “dba”

 

Groups add:

                Now we will create a group and for this I will use the linux command “groupadd”

    [root@reyaz etc]# groupadd test1

    [root@reyaz etc]# groupadd test2

after creating group you can check them by using the previous command .Given below again.

  [root@reyaz etc]# cat group

Groups delete:

                Now we will delete a group and for this I will use the linux command “groupadel”

    [root@reyaz etc]# groupdel test1

    [root@reyaz etc]# groupdel test2

rhcsa | user and group management 
User Management:

               

 At first we will see all the users are present in this system and their storage  location.

[root@reyaz ~]# cd /etc/

[root@reyaz etc]# cat passwd

 

 

Create User

                We can create a user by using below command

                 [root@reyaz etc]# useradd user10

                But we can create a user with some attribute also. See below

                 [root@reyaz etc]# useradd -u6001 -d /home/user10 -s /bin/bash user10

                          

 After creating user with some attribute you can check by using this command
                        [root@reyaz etc]# cat passwd
 

User lock:

                To lock a user use below command

                [root@reyaz ~]# usermod -L user1

 

 And to unlock a user please use below command

[root@reyaz ~]# usermod -U user1

rhcsa | user and group management 
How to assign password to users?

 To assign a password you have to use the linux command "passwd username"
After that system will ask you to type a new password. then again you have to write your new password. Remember one thing, you can not see your password while you are typing the password. Finally you will get a successful message.

rhcsa | user and group management 
How to force user to change password on next logon?

Here in this picture "0" (zero) used to force user to change the password at the first login. 


Please comment your opinion and suggestion below.  

 

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