Linux command

using: MobaXTerm (program)

Install zsh

-> better playing with command line

prerequisite

git
curl or wget

sudo apt-get update
sudo apt-get install zsh
zsh --version  # verify installtion
sh -c "$(curl -fsSL https://raw.githubusercontent.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

grep command

grep

# option
## -c count the number of word
## -w match all word
## -n show line number 
## -i ignore case matching
## -l Displays list of a filenames(match gicen pattern) only .
grep -l 'linux' <filename>, ...  # find file that contain "linux"
# ^ the starting of the line, & the end of line
grep '^kbuet'  # find kbuet at the beginning of the line
grep '^&' # find the blank line
# using . mean any char if you want to find . use \.
grep 'k...t'  # find kxxxt
# . is for 1 char; [<src_char[-dest_char]>...] is for set of matched char
grep '[Gg][Gg][Ee][Zz]' # GGEZ, GgEZ, GGeZ, ... 
grep 'LAB[1-9]_[A-Z]'  # lab[1-9]_[FOLLOW WITH LETTER A-Z]
grep 'LAB[1-9]_[^A-Z]' # lab[1-9]_[NOT FOLLOW WITH LETTER A-Z]
# match all entire word
grep '\<k.l\>' # match all word start with k end with l
# character classes
## [[:alnum:]] – Alphanumeric characters.
## [[:alpha:]] – Alphabetic characters
## [[:blank:]] – Blank characters: space and tab.
## [[:digit:]] – Digits: ‘0 1 2 3 4 5 6 7 8 9’.
## [[:lower:]] – Lower-case letters: ‘a b c d e f g h i j k l m n o p q r s t u v w x y z’.
## [[:space:]] – Space characters: tab, newline, vertical tab, form feed, carriage return, and space.
## [[:upper:]] – Upper-case letters: ‘A B C D E F G H I J K L M N O P Q R S T U V W X Y Z’.
# min max or len
## {min}, {min,max}
grep '[[:digit:]]{1,3}'  # find the digit with have len 1-3 ex. 000, 111, 929
grep '[vV]{3}' # find set of [vV] with len 3  vVv or vvv or VVV ...
# u can use 'OR' with \|
grep '[[:digit:]]{1,3}\|word2'
# and with grep ... | grep ... 

1. Install plugin

follow below instruction

https://github.com/romkatv/powerlevel10k.git

2. Plugin Configuration

inside folder plugin configuration in ~/.zshrz

...
plugins=(git
        kubectl
        kubectlx)
...

SSH key gen

ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "<email_address>"

• -o : Save the private-key using the new OpenSSH format rather than the PEM format. Actually, this option is implied when you specify the key type as ed25519.
• -a: It’s the numbers of KDF (Key Derivation Function) rounds. Higher numbers result in slower passphrase verification, increasing the resistance to brute-force password cracking should the private-key be stolen.
• -t: Specifies the type of key to create, in our case the Ed25519.
• -f: Specify the filename of the generated key file. If you want it to be discovered automatically by the SSH agent, it must be stored in the default .ssh directory within your home directory.
• -C: An option to specify a comment. It’s purely informational and can be anything. But it’s usually filled with @ who generated the key.

To set defualt ssh-key

# inside ~/.ssh/config
IdentityFile /home/<user>/.ssh/<private_key>

chmod to current user in window

icacls .\<private_key> /inheritance:r
icacls .\<private_key> /grant:r "%username%":"(R)"

Remove service in linux

export service=YOUR_SERVICE_NAME; systemctl stop $service && systemctl disable $service && rm -rf /etc/systemd/system/$service && rm -rf /usr/lib/systemd/system/$service && systemctl daemon-reload && systemctl reset-failed

git command

ถ้าเกิดเผลอใส่ข้อมูลลงไปใน git แล้วอยากลบทิ้ง

จากตัวอย่างนี้คือการลบ .env file

git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch .env" HEAD
git push --force

If you want to insert file with text in server that there's no text editor

nano
> 'nano' command not found
cat > ./.kube/config << EOL
this is line 1 msg
this is line 2 msg
...
this is line 3 msg
EOL

cat ./.kube/config
> the msg will appear here 

git using ssh

ssh-keygen
cat ~/.ssh/<public_key>

Then copy public key and attach to github repo or account

# connect to git repo
ssh -vT git@github.com [-i <path_to_private_key>]