Other

Format the flash card

mkfs -t ntfs 'Arch' -I /dev/sd*

Read ttyUSB0

chmod a+rw /dev/ttyUSB0

Search in files

find -name *.c -type f | xargs grep open

grep -R open --include="*.c".

Share the directory http://$HOSTNAME:8000/

python -m SimpleHTTPServer

Print shared object dependencies

ldd /path_to_object

Missing files or libraries

strace -eopen <application name>
LD_DEBUG=files <application name>
readelf -a /usr/bin/<application name> | grep interp
LD_DEBUG=all /lib64/ld-linux-x86-64.so.2 <application name>

Check nginx configuration

nginx -t

Search by commands history

Ctrl+R

Executing a long command

Ctrl+X,E

Terminal reinitialization

reset

Create a new UUID value

uuidgen

Cd rom access

chmod u+s /usr/bin/wodim

Read from standard input and write to standard output and files

tee

Documnentation

/usr/share/doc

Load one core

yes > /dev/null &
perl -e 'while(1){}'

Clean file

truncate -s 0 <file_name>
echo '' > <file_name>
> <file_name>
cat /dev/null > <file_name>
true | tee <file_name>
dd if=/dev/null of=<file_name>
shred <file_name>
shred -zu <file_name>

Set or retrieve a process’s CPU affinity

taskset

TAR

Create archive

tar -cvpzf archive.tar.gz /forpack

Unpack archive

tar -xzvf archive.tar.gz
tar -xfvj archive.tar.bz2 -C /var/www

View archive

tar -tf archive.tar

DHCP

Get dhcp

dhclient -v

HASH

Take sum sha1

echo -n "actual_password_here" | sha1sum | tr [:lower:] [:upper:]

Take sum like shadow

python3 -c "import crypt; print(crypt.crypt('actual_password_here', '\$6\$random_salt\$'))"

Network

Change interface speed

ethtool -s eth0 speed 100 duplex full

Create a new UUID value

uuidgen eth1

TREE

tree -d -L 2

TIME

View

timedatectl status

FAIL2BAN

View

fail2ban-client status
fail2ban-client status asterisk-udp

Unban

fail2ban-client set asterisk-udp unbanip ip_address

IPTABLES

View

iptables -n -L -v --line-numbers

RAM, SWAP

Memory use

cat /proc/meminfo

ps axo rss,comm,pid \
| awk '{ proc_list[$2]++; proc_list[$2 "," 1] += $1; } \
END { for (proc in proc_list) { printf("%d\t%s\n", \
proc_list[proc "," 1],proc); }}' | sort -n | tail -n 10 | sort -rn \
| awk '{$1/=1024;printf "%.0fMB\t",$1}{print $2}'

SYSTEMCTL

Systemd reload

systemctl daemon-reload

Restart network manager

systemctl restart NetworkManager

Masked/unmasked, Completely disabled service

sudo systemctl mask service_name
sudo systemctl unmask service_name

Environment

export var=
export var=$var

ACL

umask

View premissions

getfacl

Add default permission

setfacl -d -m u::rwx,g::r-x,o::r-x /home/test/

Remove default permission

setfacl -k /home/test/

Remove permission

setfacl -x user_name /home/test/

Recursive

setfacl -R

Remove all acl

setfacl -bn /home/test/

SED

Replace in all files

sed -i 's/old_text/new_text/g' *

Mount

Cifs

mount.cifs //host/share /mnt -o user=dmosk,domain=dmosk.local,vers=3.0

CD-rom

mount- -o loop /opt/cd.iso /opt/repo

Remount with rw

mount -n -o remount,rw /dev/sdXX

Chromium

Proxy

chromium --proxy-server="socks://host:9050"

Discard

browser://discards
chrome://discards

Task manager

Shift + ESC

Chrome Flag

browser://flags/

GPU information

browser://gpu/

Ffmpeg

Video from RTSP

ffmpeg -y -re -acodec pcm_s16le -rtsp_transport tcp -i rtsp:// -vcodec copy -af asetrate=22050 -acodec aac -b:a 96k -t 15 tmp/test.mp4

Screenshot from RTSP

ffmpeg -rtsp_transport tcp -i rtsp:// -f image2 -vf fps=fps=1 -t 0.001 -ss 00:00:3 tmp/image.png

Use find

FFMPEG_COMMAND="ffmpeg -hide_banner -loglevel error -y"
find . -type f -name "*.mp4" -print0 | while read -r -d '' file_name; do
    echo $file_name
    $FFMPEG_COMMAND -nostdin -i "$file_name" <params> - | $FFMPEG_COMMAND -i - -i "$file_name" <params> "${file_name/.mp4/}-dpni_fixed.mp4"
done

Youtube-dl / yt-dlp

Best video

youtube-dl -f bestvideo+bestaudio 'url'

Best audio

youtube-dl -f bestaudio 'url'

The list of formats

youtube-dl -F 'url'

Ldconfig

Create the cache

ldconfig

Delete the cache

rm /etc/ld.so.cache

View what libraries are in cache

ldconfig -p

Benchmark

FIO

Read

fio --name=randread --ioengine=libaio --iodepth=16 --rw=randread --bs=4k --direct=0 --size=512M --numjobs=4 --runtime=240 --group_reporting

Write

fio --name=randwrite --ioengine=libaio --iodepth=1 --rw=randwrite --bs=4k --direct=0 --size=512M --numjobs=4 --runtime=240 --group_reporting

Read & Write

fio --randrepeat=1 --ioengine=libaio --direct=1 --gtod_reduce=1 --name=test --filename=random_read_write.fio --bs=4k --iodepth=64 --size=4G --readwrite=randrw --rwmixread=75

Grep

Print only matching parts

grep -Eo "pattern" file | sort | uniq

Shutdown/Poweroff/Reboot

Shutdown

shutdown -h hours:minutes
init 0
telinit 0
shutdown -h now
poweroff
halt --poweroff
reboot --poweroff
shytdown --poweroff
halt --no-wtmp --no-wall

Cancel

shutdown -c

Poweroff

halt
halt --force
reboot --halt
poweroff --halt
poweroff --force

Reboot

poweroff --reboot
shutdown --reboot
reboot --force
halt --reboot
init 6
reboot

Problems with software

reboot -f

Problems with kernel, mount, libc

echo b>/proc/sysrq-trigger

Problems with kernel and hardware

ipmitool chassis power cycle

Problems with kernel and hardware without open console

ipmitool -H ipmi.server.local chassis power cycle

SysRq

Unraw

Alt+SysRq+r

Terminate

Alt+SysRq+e

Kill

Alt+SysRq+i

Sync

Alt+SysRq+s

Unmount

Alt+SysRq+u

Reboot

Alt+SysRq+b

Logrotate

Check the configuration file

logrotate -d /etc/logrotate.d/config_name

Sox

Convert to VoIP format

sox -V vm-intro.wav -r 8000 -c 1 -t ul vm-intro.ulaw
sox -V vm-intro.wav -r 8000 -c 1 -t al vm-intro.alaw
sox -V vm-intro.wav -r 8000 -c 1 -t gsm vm-intro.gsm

Udevadm

Show in realtime

udevadm monitor

Get attributes

udevadm info /dev/sdb1

Chattr

Make immutable

chattr +i <file name>

Only append

chattr +a <file name>

Kernel compress/decompress

chattr +c <file name>

Ignore when dump

chattr +d <file name>

Security remove

chattr +s <file name>

Remove with save data

chattr +u <file name>

Sync on disk

chattr +S <file name>

Show the file attributes

lsattr file_name

Cache

Clean

Write cache to persistent storage

sync

PageCache

sync; echo 1 > /proc/sys/vm/drop_caches

Inode and dentrie

sync; echo 2 > /proc/sys/vm/drop_caches
sysctl -w vm.drop_caches=3

Inode, dentrie and PageCache

sync; echo 3 > /proc/sys/vm/drop_caches

Swap

swapoff -a && swapon -a

Percentage value controls the tendency of the kernel to reclaim the memory which is used for caching of directory and inode objects

echo 1000 > /proc/sys/vm/vfs_cache_pressure

GPG

Import key

gpg --keyserver keys.gnupg.net --recv-keys key

Generate key pair

gpg --full-gen-key

Show private keys

gpg --list-secret-keys --keyid-format LONG <email>

Export public key

gpg --armor --export <key_id>

Slmgr

Install or replace the product key

slmgr /ipk product_key

Install kms host

slmgr /skms host_name:port

Activation windows

slmgr /ato

Nmcli

Show devices

nmcli device show

Entropy

View the size of the entropy pool

cat /proc/sys/kernel/random/poolsize

View status of server’s entropy

cat /proc/sys/kernel/random/entropy_avail

Cp

Copy with attributes mode,ownership,timestamps

cp -rp /source /destination

Copy with save all parameters

cp -a /source /destination

Backup

cp <file name>.txt{,.bak}

Shred

Overwrite a file and delete

shred -zvu -n 10 file_name

Overwrite a file

shred -zv -n 10 file_name

Overwrite a partition

shred -fvz /dev/sdXX

Man

Description of the filesystem hierarchy

man hier

ASCII table

man ascii

Curl

REST API get

curl --include --location --request GET 'https://site_name/?fields=parameter_name' --header 'Authorization: OAuth id'

Formatting JSON answer

curl --location --request GET 'https://site_name/?fields=parameter_name' --header 'Authorization: OAuth id' | python -m json.tool

Download file

curl --location --remote-name https://<url to file>

Nohup

Run command immune to hangups

nohup command

Run command in background

nohup command &

Sudo

Run shell as another user

sudo -iu user_name
sudo su - user_name command
sudo su user_name -s "/bin/bash"

Executing the previous command

sudo !!

Write command results to file with privileges

echo 1 | sudo tee -a privileged_file > /dev/null

SU

Run shell as another user

su - user_name
su -l user_name
sudo su - user_name

QEMU

LiveUSB

qemu-system-x86_64 -hda /dev/sdX

Kubectl

Network utils

kubectl run -it --rm --image amouat/network-utils test bash

Certbot

Create certificate certbot.ini

authenticator = standalone
noninteractive = true
agree-tos = true
rsa-key-size = 2048

certbot certonly --config ./certbot.ini --email <e-mail address> --work-dir </var/lib/letsencrypt> --config-dir <where save data> --domain <domain_name>

Renew certificate

certbot renew --work-dir </var/lib/letsencrypt> --config-dir <where save data>

Scl

Activate python environment

scl enable rh-python<version_numver> bash

Tail

Terminate tail when proccess over

tail -f <file name> --pid=<PID>

Whait when file exist

tail -f <file name> --retry

Wine

Run application with prefix

Create prefix

env WINEPREFIX=<apth to prefix> winecfg

Update prefix

env WINEPREFIX=<apth to prefix> wineboot -u

env WINEPREFIX=<apth to prefix> wine <path to appliaction>

Keyring

Get key

keyring get <service name> <username>

Secret tool

Get key

secret-tool lookup <attribute> <value>