Im a linux junky, so I'll try to explain it...I'm sure the sites above give a good explaining.. but who wants to visit another site?
chmod stands for "
Change
Mode".
The numbers part is a little more complicated.... "777" is three numbers..to be nerdy and specific.. it is three 3 digit binary (base 2) numbers converted into three 1 digit octal (base 8) numbers.
The first number stands for "user", the second group stands for "group" and the final number stands for "other". There are three possible things that can be done with a file: read, write, and execute.. Here is a little reference:
execute = 001 in binary = 1 in octal
write = 010 in binary = 2 in octal
read = 100 in binary = 4 in octal
So where does the 7 come from?
7 in binary = 111 in decimal = read, write, execute
So you get:
read write execute = 111 = 1 + 2 + 4 = 7
read write no execute = 110 = 4 + 2 = 6
read no write execute = 101 = 4 + 1 = 5
read no write no execute = 100 = 4
no read write execute = 011 = 2 + 1 = 3
no read write no execute = 010 = 2
no read no write execute = 001 = 1
no read no write no execute = 000 = 0
Make sense?
To make a file "chmod 777" you would simply type:
chmod 777 filename.ext
in the terminal.