linux.md

Network

Traceroute

調查連接到某部主機時，經過的每個節點以及連線速度

traceroute google.com

Check port usage

Check specific port usage

lsof -i :3000 | grep LISTEN

List port usage

lsof -PiTCP -sTCP:LISTEN

netstat -aep | grep ':\*'

netstat -ltunp

Check remote host port usage

nc -vz example.com.or.ip 80

telnet example.com.or.ip 80

Check DNS record

nslookup example.com

dig example.com

host example.com

scp

從遠端抓取檔案

scp username@serverhost:/file/on/server /local/path

scp -r username@serverhost:/folder/on/server /local/path

複製檔案或資料夾到遠端

scp localfile username@serverhost:/filename

scp -r localfolder username@serverhost:/foldername

Grep

Find keyword in file

grep keyword filename

Find keyword by command result

some command | grep keyword

Edit

Create file

touch filename

Show file content

cat filename

Append string into file

cat >> filename

Disk

Check disk usage

df -h

Check file size in the directory

du -hmd 1

Check sum of filesize in the directory

du -sh

Process

Check process

ps aux

top

Kill process

kill -9 PID

SSH

Gen ssh key

ssh-keygen

Send ssh key to remote server

ssh-copy-id username@host

Timezone

ln -snf /usr/share/zoneinfo/Asia/Taipei /etc/localtime