linux commands and information i find useful.

linux

permissions  : information about getting file permissions
flaskdrive   : flashdrive commands
pipeline     : redirecting stdout and stderr
wget         : wget to save a site offline
openssl      : openssl options
certificates : types of certs and their purpose
commands     : general useful commands
ssh          : Useful SSH configurations
torrent      : Torrent client
audio        : Audio configuration help

linux:audio

# Record Audio (10 seconds)
arecord -f cd -d 10 test-mic.wav
# Play audio
aplay test-mic.wav

linux:certificates

   Filename    ||         Needed By          ||              Purpose           ||   Secret
===============++============================++================================++===========
  ca.crt       ||    Server + Clients        ||     Root CA certificate        ||  NO
  ca.key       ||  Key Signing Machine only  ||     Root CA key                ||  YES
  dh.pem       ||        Server only         ||     Diffie Hellman parameters  ||  NO
  server.crt   ||        Server only         ||     Server Certificate         ||  NO
  server.key   ||        Server only         ||     Server Key                 ||  YES
  client.crt   ||        Client only         ||     Client Certificate         ||  NO
  client.key   ||        Client only         ||     Client Key                 ||  YES

linux:commands

xinput --list --short
xinput --list-props <device>
xinput set-prop <device> <property> <value>
xrandr -q                  # Show all display options 
xrandr -s 1366x768 -r 40   # Set display refresh rate

linux:cryptsetup

# LuksFormat
sudo cryptsetup --key-size 512 --hash sha512 -v luksFormat /dev/<drive> --verify-passphrase
sudo cryptsetup config /dev/<drive> --label <LABEL>

# LuksOpen
sudo cryptsetup luksOpen /dev/<drive> <LABEL>

# LuksFormat (w/ header)
sudo cryptsetup --key-size 512 --hash sha512 -v luksFormat /dev/<drive> --verify-passphrase --header ~/<header-name>
sudo cryptsetup config /dev/<drive> --label <LABEL>

# LuksOpen (w/ header)
sudo cryptsetup luksOpen /dev/<drive> <LABEL> --header ~/<header-name>

# Mount & Format
sudo mkfs.ext4 /dev/mapper/<drive>
sudo mkdir -p /media/<drive>
sudo mount /dev/mapper/<drive> /media/<drive>
sudo chown -R <user>:<user> /media/<drive>

# LuksClose & umount
sudo umount /dev/mapper/<drive>
sudo cryptsetup luksClose /dev/mapper/<drive>
sudo rm -rf /media/<drive>

linux:download-nmcli

apt-get download $(apt-cache depends --recurse --no-recommends --no-suggests \
  --no-conflicts --no-breaks --no-replaces --no-enhances \
  --no-pre-depends network-manager | grep "^\w")

linux:flashdrive

sudo fdisk -l
sudo umount /dev/sdb1
sudo wipefs --all /dev/sdb1
sudo cfdisk /dev/sdb1 
sudo dd bs=4M if=/path/to/iso of=/dev/sdb status=progress && sync
# Running unetbootin
sudo QT_X11_NO_MITSHM=1 unetbootin
# Recover Corrupt GPT
sudo gdisk /dev/sdb

linux:openssl

OpenSSL 1.1.1d  10 Sep 2019

Encrypt Large Files: openssl enc -aes-256-cbc -salt -pbkdf2 -in file.txt -out file.txt.enc
Options	      Description
openssl	      OpenSSL command line tool
enc	          Encoding with Ciphers
-aes-256-cbc	The encryption cipher to be used
-salt	        Adds strength to the encryption
-in	          Specifies the input file
-out	        Specifies the output file.

Decrypt Large Files: openssl enc -aes-256-cbc -d -pbkdf2 -in file.txt.enc -out file.txt
Options	      Description:
-d	          Decrypts data
-in	          Specifies the data to decrypt
-out	        Specifies the file to put the decrypted data in

linux:permissions

0 – no permission
1 – execute
2 – write
3 – write and execute
4 – read
5 – read and execute
6 – read and write
7 – read, write, and execute


owner group other
read  (r)              4          4          4
write  (w)             2          2          2
execute  (x)           1          1          1
-----------        -----      -----       -----
total  value           7          7          7

stat FILE_NAME
stat -c %a FILE_NAME

linux:pipeline

          || visible in terminal ||   visible in file   || existing
  Syntax  ||  StdOut  |  StdErr  ||  StdOut  |  StdErr  ||   file   
==========++==========+==========++==========+==========++===========
    >     ||    no    |   yes    ||   yes    |    no    || overwrite
    >>    ||    no    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
   2>     ||   yes    |    no    ||    no    |   yes    || overwrite
   2>>    ||   yes    |    no    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
   &>     ||    no    |    no    ||   yes    |   yes    || overwrite
   &>>    ||    no    |    no    ||   yes    |   yes    ||  append
          ||          |          ||          |          ||
 | tee    ||   yes    |   yes    ||   yes    |    no    || overwrite
 | tee -a ||   yes    |   yes    ||   yes    |    no    ||  append
          ||          |          ||          |          ||
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    || overwrite
 n.e. (*) ||   yes    |   yes    ||    no    |   yes    ||  append
          ||          |          ||          |          ||
|& tee    ||   yes    |   yes    ||   yes    |   yes    || overwrite
|& tee -a ||   yes    |   yes    ||   yes    |   yes    ||  append

linux:ssh

# Exit automatically on network interruptions. In your .ssh/config, add:
ServerAliveInterval 5
ServerAliveCountMax 1

linux:torrent

docker run -d \
  --name=rutorrent \
  -e PUID=1000 \
  -e PGID=1000 \
  -p 8090:80 \
  -p 5000:5000 \
  -p 51413:51413 \
  -p 6881:6881/udp \
  -v /<path>/config:/config \
  -v /<path>/downloads:/downloads \
  ghcr.io/linuxserver/rutorrent

linux:wget

wget \
     --recursive \
     --no-clobber \
     --page-requisites \
     --html-extension \
     --convert-links \
     --domains example.com \
     --no-parent \
         example.com/section/topic/