Useful Linux Commands

• Check Port in ubuntu

sudo ss -ltnp | grep 8754

• Check connection to port

netstat -alnp | grep 3306

• Check where is process run

ls -la /proc/3126/exe

• Check syslog

tail -n 200 /var/log/syslog

• Show log service

sudo journalctl -u docker.service
sudo journalctl -u docker -n 100 --no-pager

• Kill process

sudo kill -9 $(pgrep dockerd)

• Switch version in linux

sudo alternatives --config java

EX:
verison 17 => /usr/lib/jvm/java-17-amazon-corretto.aarch64/bin/java
verison 11 => /usr/lib/jvm/java-11-amazon-corretto.aarch64/bin/java

• Count file in folder and sub folder

find . -maxdepth 1 -type d | while read -r dir do printf "%s:\t" "$dir"; find "$dir" -type f | wc -l; done

• Find file with content

grep -rnw '/path/to/somewhere/' -e 'pattern'

• Find large file

find . -type f -size +100M

• Check list folder large

sudo du -sh --exclude=/proc --exclude=/sys --exclude=/dev --exclude=/run /* | sort -rh | head -n 10


sudo du -sh * | sort -rh | head -n 10

• Check volume id map in ec2 ubuntu

udevadm info -q all -n /dev/nvme3n1

• Caculate size and sort in linux

sudo du -h -d 1 /Users/$(whoami) | sort -hr

• Backup remote

tar czvf - /home/user/public_html | ssh user@server-backup "cat > /opt/website_backup.tar.gz"