Which

which <program> # 查program實際位置
                # which date / which echo

File/Folder

touch filename
touch test-{a, b, c}.txt  # test-a.txt test-b.txt test-c.txt
mdkir foldername

du

du -sh foldername/filename

Move

cd -      : go to previous directory
cd / cd ~ : go to home directory

Type

• C-u : delete all line
• C-w : delete word

Search 搜尋

• ctrl + r type keyword to search history command
• !! <Enter>

grep -r "keyword" .

brew install ripgrep

rg <word>

在多層目錄中找到filename.txt的路徑

find /usr/bin -type f -name "filename"
find ~/Downloads -type f -mtime +30  # 30天以上的file
find ~/Downloads -type f -size +100M -exec ls -lh {} \;
find . -name "*.md"  -exec grep -l "TODO" {} \;

Awk

# cat data
# a b c
# d e f
# g h i

awk '{print $2}' data
# b
# e
# h

awk -F , '{print $2}' data # 用','區分

Kill process running port

lsof -i:3000
kill <PID>

目錄大小

du -sh <path>

For Loop

for varname in a b c d; do echo "$varname"; done
# a
# b
# c
# d

for varname in $(seq 1 5); do echo "$varname"; done
# 1
# 2
# 3
# 4
# 5

If

if [ "hello" = "world" ]; then echo "equal"; else echo "not equal"; fi
# not equal

ssh

ssh {url} -l {login_name} -p {port}
scp {filename} {user}@{ip}:{path} # 從本地端複製檔案到遠端機器上

wget

wget {url} 把檔案抓下來

netcat

TCP/IP 瑞士刀 (Swiss Army Knife)

nc <host> <port>

nc example.com 12345

import socket

s = socket.socket()
s.connect(("example.com", 12345))

while True:
    data = input("> ")
    s.send(data.encode())

    response = s.recv(4096)
    print(response.decode())

strings

把binary file -> string

strings -a -t x file
-a   : all
-t x : 十六進位顯示

讀檔

open('dictionary.txt', 'rb').read()
open('dictionary.txt', 'r').read().splitlines()
open('dictionary.txt', 'rb').read().decode('utf-8')

更改權限

chmod +x filename

# read    r 4
# write   w 2
# execute x 1

Encode/Decode

echo "xxxxx" | base64 -d

查看檔案

xxd filename       # 二進位資料和十六進位之間互相轉換
exiftool filename  # 看 Metadata
strings filename   # 從二進位檔案中找出「可列印文字」的工具

Tmux

Resource

Lecture 1: Course Overview + Introduction to the Shell - YouTube