• 06 July 2025
• cheatsheet

User

• sudo adduser [newuser] create a new user
• sudo usermod -aG [group] $USER to add group into current user sudo usermod -aG sudo [user] to add user to sudo

Filesystem

• du -sh * | sort -h tampilan directory berdasarkan urutan size
• du -sh * | sort -rh untuk reverse

System

Port

• sudo lsof -i :443 -sTCP:LISTEN check siapa yang menggunakan port tertentu
• sudo netstat -anv -p tcp | egrep 'Proto|(\*\.(80|443))'
• sudo lsof -i -P -n | grep 80
• lalu gunakan ps -p [pid] untuk melihat detail proses-nya
• sudo kill <process id>

Process

• ps
• ps -p [pid] melihat siapa yang menggunakan
• du -h | sort --key=2 menampilkan folder beserta ukurannya dan di sortir untuk koom 2 (filename). Defaultnya sortir terhadap filesilze di kolom 1

CHMOD & FACL

Chmod recursively

// recursively 755 and 664
chmod -R a=,a+rX,u+w,g+w /some/path/here

Step 1: Create Backup

First make a backup incase anything goes wrong someday:

mkdir ~/storage-changes
sudo getfacl -R /var/www > ~/storage-changes/default_www_facl

(Incase) To Restore

sudo setfacl --restore=~/storage-changes/default_www_facl 

Apply ACL

Next, apply to a group:

# -R is recursive
# -m is modify
# -d applies to default ACL

sudo chgrp -R www-data /var/www
sudo setfacl -Rd g:www-data:rwX /var/www
sudo setfacl -Rdm g:www-data:rwX /var/www

ls -lta /var
sudo getfacl /var/www

The + at the end of the file/dir listing only means it has additional ACLs.

MISC

Create New File via Right Click

• See if you have ~/Templates folder. Create one if it is missing using command:

mkdir ~/Templates

• Now create an empty file from command prompt:

touch ~/Templates/Text\ File.txt

• History, clear history history -cw

Diff

• diff -cw [file1] [file2] difference while ignoring whitespace in context view
• diff -yw [file1] [file2] difference while ignoring whitespace and in 2 column view