리눅스 파일, 디렉토리 명령어(linux file/directory command) 3. permission

1. permission

1-1 read, write, execute

	regular file	directory	special file
read(r)	read or copy	read(list its contains)	read by system call
write(w)	change or delete	add or remove its contains	written by system call
execute(x)	execute if program	access, reference, move	no meaning

it also refered as octal number

r	w	x
digit 4	digit 2	digit 1

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2. change mode

chmod mode file

• symbolic mode

who
u	user
g	guest
o	other
a	all

operation
=	assign
+	add permission
-	remove permission

chmod u=rwx,g+w,o-w file1

• octal

chmod 755 file1

  the above command changes file1 with permision rwxr_xr_x.

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3. user mask

set file/directory under working directory with complementary permission(only in octal)

umask 026

Mask	directory	file(not functioning in 'x')
0	rwx(7)	rw_(6)
1	rw_(6)	rw_(6)
2	r_x(5)	r__(4)
3	r__(4)	r__(4)
4	_wx(3)	_w_(2)
5	_w_(2)	_w_(2)
6	__x(1)	___(0)
7	___(-)	___(0)