chmod

• The user is the user who created it (the owner of the file ).
• The group is the group of the owner
• others are all the other users
• a stands for all (u+g+o)

type	user (u)	group (g)	others (o)
-	rwx	rwx	rwx

• rwx: Read, Write, eXecute
• E.g., 421, 421, 421, 700

rwx	rw-	r-x	r--	-wx	-w-	--x	---
7	6	5	4	3	2	1	0

chmod +x "file" # Make the file executable for all (u+g+o)
chmod 700 "file" # User can rwx, the rest can do nothing
chmod 731 "file" # User rwx, group -wx, others --x
chmod g-w "file" # Remove "write" from "group"
chmod a-r "file" # Remove "read" from all
chmod o+x "file" # Add "read" to others
chmod u-r "file" # Remove "read" from user
chmod a+rwx "file" # Add "read-execute" to all

Directory permissions

• Folders MUST have executable permission (+x) in order to be accessible (cd into it)

# Default folder permission
chmod 755 "folder"

# Default file permission
chmod 644 "file"