Useful Linux Commands.

while booting the system if you get any error line "Linux system from maintenance mode".

Resolve:-
              first, use the administrator user and password to enter to the console.
               just type the following command and reboot the machine. 
                           :- mount -o remount, rw /
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nmtui - Text User Interface for controlling NetworkManager

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 lspci  - is  a  utility for displaying information about PCI buses in the system and devices connected to them.
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ethtool - query or control network driver and hardware settings

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systemctl list-unit-files --type=service ( TO VIEW THE ALL SERVICES)


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LS Commands:-

ls -i

Disk View Commands:-

df –hT     [it will print partitions along with filesystem type]

lsblk        [it print all block devices]

fdisk –l   [List the partition tables for the specified devices and

then exit.  If no devices are given, those mentioned in /proc/partitions (if that exists) are used.]

sfdisk –l  [it will print the disks with cylinders and blocks]

               -l list the partitions of a devices.

               -s list the size of a partitions.

-u, -uS, -uB, -uC, -uM [accept or report in units of sector  (cylinders, blocks, megabytes….)]

parted /dev/sda [ listing the partition size is larger than 1 or 2 TB]

               (parted) unit TB [ it will convert the disk size in to TB] 
               (parted) print [ it will print the partition in TBs]

               (parted) quit [ to quit from parted command]

lsscsi          [ it will print the SCSI devices and their attributes ]