Linux cheat sheet

apt.md

APT cheat sheet

apt or apt-get

apt install and --reinstall
    remove
    purge or --purge
    upgrade
    update
    clean and autoclean

get info available version of package

apt-cache   policy  <package name> 
            search
            show

Update package index files from sources.list

apt update

Clear the APT cache

apt  clean

Remove useless files from the APT cache

apt autoclean

bootloader.md

Info about bootloader

wich bootloader

# 1
sudo dd if=/dev/sda bs=512 count=1 2>/dev/null | strings | grep -Eoi 'grub|lilo|acronis|reboot'

#2 
dd if=/dev/hda bs=512 count=1 2>&1 | grep GRUB
dd if=/dev/hda bs=512 count=1 2>&1 | grep LILO

links

https://askubuntu.com/questions/24459/how-do-i-find-out-which-boot-loader-i-have

disk.md

Disk cheat sheet

NVME device information

sudo apt-get install nvme-cli
sudo nvme list
sudo nvme id-ctrl /dev/nvme0n1

# Get info about smart
sudo nvme smart-log /dev/nvme0
sudo nvme smart-log-add /dev/nvme0

# Additional info
sudo nvme id-ctrl /dev/nvme0 -H
sudo nvme id-ns /dev/nvme0n1 -H
sudo nvme show-regs /dev/nvme0n1 -H

Info how to manage a partion / disk / lvm / mdadm in Linux

Partion

Copy / backup partion

# GPT-Tables
# copy partion to file and restore
sgdisk --backup=sda_table /dev/sda
sgdisk --load-backup=sda_table /dev/sdb
sgdisk -G /dev/sdb

# Backup and Restore from /dev/sda to /dev/sdb in one command:

sgdisk -R /dev/sdb /dev/sda

# Finally randomize the GUID of all partitions on the disk:

sgdisk -G /dev/sdb

# MBR 
# Copy table from /dev/sda to /dev/sdb:

sfdisk -d /dev/sda | sfdisk /dev/sdb

# (Optional)If you don't see the partitions, read it again:

sfdisk -R /dev/sdb

Use util DD

Check a progress of dd

# 1
sudo apt-get install pv

# Example
dd if=/dev/urandom | pv | dd of=/dev/null


# 2
dd if=/dev/urandom of=/dev/null status=progress

# 2
# run procces dd
# open another terminal
sudo kill -USR1 $(pgrep ^dd)

# This will display dd progress in the dd terminal window without halting the process.
# If you're on BSD or OS X, use INFO instead of USR1. The USR1 signal will terminate dd.

# repeat 
watch -n5 'sudo kill -USR1 $(pgrep ^dd)'

HDD/SSD storage test

# clean disk
dd if=/dev/zero of=/dev/sdz bs=2M oflag=direct

apt-get install fio

# 1
fio -ioengine=libaio -name=test -direct=1 -filename=/dev/sdX \
  -bs=4k -rw=randwrite -iodepth=1 -fsync=1
  -bs=4k -rw=randwrite -iodepth=128
  -bs=4M -rw=write -iodepth=16

#2
# IOPS Performance Tests

# Test random reads
sudo fio --filename=device name --direct=1 --rw=randread --bs=4k --ioengine=libaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1 --readonly
# Test file random read/writes
sudo fio --filename=/custom mount point/file --size=500GB --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1
sudo fio --filename=/home/administrator/temp/fio_file --size=20GB --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=256 --runtime=240 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1
# Test device random read/writes
sudo fio --filename=device name --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1
# Test device random read/writes 16/16
sudo fio --filename=device name --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=16 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1
# Test sequential reads
sudo fio --filename=/dev/sdb --direct=1 --rw=read --bs=4k --ioengine=libaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1 --readonly

# Throughput Performance Tests

# Test random reads
sudo fio --filename=device name --direct=1 --rw=randread --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4 --time_based --group_reporting --name=throughput-test-job --eta-newline=1 --readonly
# Test file random read/writes
sudo fio --filename=/custom mount point/file --size=500GB --direct=1 --rw=randrw --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4 --time_based --group_reporting --name=throughput-test-job --eta-newline=1 
# Test device random read/writes
sudo fio --filename=device name --direct=1 --rw=randrw --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4 --time_based --group_reporting --name=throughput-test-job --eta-newline=1
# Test sequential reads
sudo fio --filename=device name --direct=1 --rw=read --bs=64k --ioengine=libaio --iodepth=64 --runtime=120 --numjobs=4 --time_based --group_reporting --name=throughput-test-job --eta-newline=1 --readonly

# Latency Performance Tests

# Test random reads for latency
sudo fio --filename=device name --direct=1 --rw=randread --bs=4k --ioengine=libaio --iodepth=1 --numjobs=1 --time_based --group_reporting --name=readlatency-test-job --runtime=120 --eta-newline=1 --readonly
# Test random read/writes for latency
sudo fio --filename=device name --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=1 --numjobs=1 --time_based --group_reporting --name=rwlatency-test-job --runtime=120 --eta-newline=1 --readonly

Links

https://askubuntu.com/questions/57908/how-can-i-quickly-copy-a-gpt-partition-scheme-from-one-hard-drive-to-another https://tech.feedyourhead.at/content/copy-partition-table-one-disk-another https://www.cyberciti.biz/faq/linux-backup-restore-a-partition-table-with-sfdisk-command/ https://askubuntu.com/questions/215505/how-do-you-monitor-the-progress-of-dd

NVME

https://www.percona.com/blog/2017/02/09/using-nvme-command-line-tools-to-check-nvme-flash-health/ https://unix.stackexchange.com/questions/472211/list-features-of-nvme-drive-like-hdparm-i-for-non-nvme https://wiki.archlinux.org/index.php/Solid_state_drive/NVMe

IOPS

http://recoverymonkey.org/2012/07/26/an-explanation-of-iops-and-latency/ https://habr.com/ru/post/154235/

ipmitool.md

IPMI cheat sheet

Change IP

# Get info
ipmitool lan print
ipmitool lan print 1
ipmitool lan set 1 ipsrc [ static | dhcp ] 
ipmitool lan set 1 ipaddr {YOUR DESIRED IP}
ipmitool lan set 1 netmask {YOUR NETMASK}
ipmitool lan set 1 defgw ipaddr 10.0.1.1

Get and change LAN mode

# To Get Lan Mode for Supermicro

ipmitool raw 0x30 0x70 0x0C 0x00

# return code:
# 00 dedicated
# 01 shared
# 02 Failover

# Set Lan Mode

# for dedicated
ipmitool raw 0x30 0x70 0x0C 0x01 0

# for shared
ipmitool raw 0x30 0x70 0x0C 0x01 1

# for failover
ipmitool raw 0x30 0x70 0x0C 0x01 2

Factory reset from OS or reset

# Reset IPMI
ipmitool mc reset cold
ipmitool bmc reset cold

# Factory reset
ipmitool raw 0x30 0x40

Boot

# Modify boot device for the next reboot
ipmitool chassis bootdev pxe 
ipmitool chassis bootdev cdrom 
ipmitool chassis bootdev bios

Links

https://serverfault.com/questions/361940/configuring-supermicro-ipmi-to-use-one-of-the-lan-interfaces-instead-of-the-ipmi https://www.supermicro.com/support/faqs/faq.cfm?faq=9848 https://serverfault.com/questions/361940/configuring-supermicro-ipmi-to-use-one-of-the-lan-interfaces-instead-of-the-ipmi https://www.atlex.ru/baza-znanij/rukovodstva/instruktsiya-po-cold-reset-i-smene-parolya-ipmi-iz-os/ https://portal.nutanix.com/page/documents/kbs/details?targetId=kA00e000000CrKRCA0 https://community.pivotal.io/s/article/How-to-work-on-IPMI-and-IPMITOOL?language=en_US https://www.thomas-krenn.com/en/wiki/Configuring_IPMI_under_Linux_using_ipmitool

iptables.md

Iptables cheat sheet

iptables manage

stop or disable

#  firewalld on CentOS Linux 7/RHEL v7 and newer

$ sudo systemctl disable firewalld
$ sudo systemctl stop firewalld
$ sudo systemctl status firewalld

# Ubuntu Linux

$ sudo ufw disable

# firewall on older version of CentOS/RHEL version 6.x and earlier

service iptables save
service iptables stop
chkconfig iptables off

Clean rules

# Some examples

iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT

Links

• Linux Disable / Remove The Iptables Firewall

smartctl.md

Smartctl cheat sheet

info

Test a disk

# Short test

smartctl -t short /dev/sdb

# wait couple minute

smartctl -l selftest /dev/sdb

Links

https://www.thomas-krenn.com/en/wiki/Analyzing_a_Faulty_Hard_Disk_using_Smartctl https://serverfault.com/questions/313649/how-to-interpret-this-smartctl-smartmon-data https://www.opennet.ru/base/sys/smart_hdd_mon.txt.html

vim.md

VIM cheat sheet

info

Enable Syntax Highlighting

yum -y install vim-enhanced

# Edit file /etc/profile.d/vim.sh

vi /etc/profile.d/vim.sh

# comment line “[ -n “$ID” -a “$ID” -le 200 ] && return“.
# save after that logout and login

Links

https://www.thegeekdiary.com/how-to-enable-text-colour-in-vi-similar-to-vim-in-centosrhel/

zfs.md

ZFS cheat sheet

info

Status of a pool

zpool status -v 

zpool status -v rpool

# with device name
zpool status -vL rpool

How to add a drive to a ZFS mirror

zpool attach [poolname] [original drive to be mirrored] [new drive]

# An example
zpool attach rpool /dev/sda /dev/sdb

How to remove a drive from a pool

zpool offline rpool /dev/sdb
zpool remove rpool /dev/sdb
# or
zpool detach rpool /dev/sdb

ZFS Data Scrubbing

# start
zpool scrub rpool

# stop
zpool scrub -s rpool

Autoextend ZFS pool

zpool set autoexpand=on rpool
watch zpool status -v
zpool status -v
zpool online -e rpool /dev/sdb2
zpool online -e rpool /dev/sda2
zpool set autoexpand=off rpool
zpool status

Scrub

zpool scrub rpool

Change disk in ZFS

#### sda

# Offline sda
zpool status -v
zpool offline rpool /dev/sda2
smartctl -a /dev/sda
hdparm -I /dev/sda

# Add new sda
sgdisk -R /dev/sda /dev/sdb
sgdisk -G /dev/sda
fdisk -l
dd if=/dev/sdb1 of=/dev/sda1
zpool replace rpool /dev/sda2 /dev/sda2
zpool status -v

# offline sdb
zpool status -v
zpool offline rpool /dev/sdb2

# Add new sdb
sgdisk -R /dev/sdb /dev/sda
sgdisk -G /dev/sdb
fdisk -l
dd if=/dev/sda1 of=/dev/sdb1
zpool replace rpool /dev/sdb2 /dev/sdb2
zpool status -v

Links

https://edmondscommerce.github.io/replacing-failed-drive-in-zfs-zpool-on-proxmox/