chmod Overview

chmod is linux command to control file permission

usage

chmod [u|g|o|a][=|+|-] [r|w|x]

u => user

g => group

o => other

a => all

r => read

w => write

x => execute

example

chmod +wr test.txt give write and read permission for user

chmod -r test.txt remove read permission for user

chmod g=wrx test.txt give write, read and execute permission for group

use number

specific the bits 011101110111 => -rwx-rwx-rwx

r = 4; w = 2; x = 1; rwx = 4+2+1; rw = 4+2

chmod u=rwx g=rw o=x test.txt <=> chmod 761 test.txt