Linux sysadmin scratchpad

linux essentials
tux academy
logon to system – check user, check bash, check groups
$ whoami # shows current user
$ pwd # shows current directory
$ getent passwd # prints content of the /etc/passwd file
$ passwd # changes current users password
$ members sudo # lists all members of group sudo
$ members root # lists all members of group root

https://www.tecmint.com/how-to-check-disk-space-in-linux/
check hdd/ssd setup and disk utilization
$ lsblk # lists all block devices in tree diagramm
$ fdisk -l # lists all disk/volumes with additional information
$ lshw -c disk # list all hardware in the disk class
$ df -h # shows disk utilization in human readable format

https://www.cyberciti.biz/faq/linux-creating-software-raid-one-arrays/
check raid

$ cat /proc/mdstat # displays the content of the mdstat file, shows state of  all mds
$ mdadm -D /dev/md0 # shows the current state of a md device in detail  (multiple devices admin -Detail)

Analyzing a Faulty Hard Disk using Smartctl
check SMART
$ smartctl -a /dev/sda # displays all smart info for sda

$ top # gives an overview of system resources and current running processes
$ free -h -t # human readable display of ram utilization and swap disk

https://www.linux.com/learn/replacing-ifconfig-ip
network adapter check n manipulation
$ ip a # lists information about current network adapters
$ ifconfig # old command to do the same

SMB / CFIS / SAMBA / NFS / Bare Metal

Übersicht über Network Filesystem Protokolle und Implementierungen:

SMB ( Server Message Block – File Sharing Protocol )
SMB 1 ( Implemented in CFIS, Common Internet File Sharing)
SMB 1.0/CIFS File Sharing Support has been disabled on Windows 10 Fall Creators Update version 1709 and higher.
SMB 2
SMB 3 ( Implemented in Windows since Win 8.1 / Win Server 2012 )

Samba ( Implementation of SMB in Linux, can be used as Active Directory Domain Controller )

NFS ( Networked File System from SUN/Microsystems – seperate File Sharing Protocol, incompatible with SMB )

System & Service Level Storage
CEPH
(Object-, Block-, File Storage service)
Openstack
(Object-, Block-, File Storage service)

unraid (OS largly confined to one machine)

Storage Implementation Levels
Device, System, Interface