chmod examples

Example 1: bash how do permissions work

# How permissions/changing permissions works in linux. Permissions are
#	generally listed in a format like rwxrw-r--, where r, w, x, and - 
#	stand for read, write, execute, and no permission respectively. There 
#	are basically three groups of rwx permissions: user, group, others
#	and depending on your relationship to the files, you might be any one
#	of these. 

#	To change file permissions, (e.g. chmod ### file), you need to 
#	indicate three decimal digits (0-7) which specify the three sets
#	of permissionswhen converted to binary. Briefly, a decimal number
#	between 0 and 7 can be represented by a three digit binary string.
#	The binary string sets the permissions by treating 1 as "true" or 
#	permission granted and 0 as "false", or permission denied. See the
#	table below for all the conversions and their meanings:

Decimal		Binary		Permission		Permission meaning
7			111			rwx				read, write, and execute
6			110			rw-				read and write
5			101			r-x				read and execute
4			100			r--				read only
3			011			-wx				write and execute
2			010			-w-				write only
1			001			--x				execute only
0			000			---				none

Example 2: chmod

chmod u=rwx,g=rx,o=r myfile

chmod 754 myfile

# 4 stands for "read",
# 2 stands for "write",
# 1 stands for "execute", and
# 0 stands for "no permission."

Example 3: chmod values

The three rightmost digits define permissions for the:
file user, the group, and others. 

Example usage: sudo chmod 777 testfile.txt

#	Permission				rwx	Binary
7	read, write and execute	rwx	111
6	read and write			rw-	110
5	read and execute		r-x	101
4	read only				r--	100
3	write and execute		-wx	011
2	write only				-w-	010
1	execute only			--x	001
0	none					---	000