chmod permission

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what is chmod

chmod means change mode . chmod can change the file permission.

short hand Full
u user
g group
o other

chmod basic

# cli
ls -l
# output
drwxrw-r--

user = first 3 position without d = rwx group = next 3 position = rw- other = last 3 position = r–

  • first position d is type

permission lists

img

cli name Full name number value
r read 4
w write 2
x excute 1
- not permit 0
user = rwx => 4+2+1 = 7
group = rw- => 4+2+0 = 6
others = r-- => 4+0+0 = 4

last result => chmod 764 => rwxrw-r--

binary system

  • permission = 1
  • no permit = 0
user = rwx => 111 => binary to decimal => 7
group = rw- => 110 => binary to decimal => 6
others = r-- => 100 => binary to decimal => 4

last result=> chmod 764 => rwxrw-r--

chmod pettern

chmod <options> <permissions> <filename>

  • options
  • -R recursive, i.e. include objects in subdirectories
  • -f force, forge ahead with all objects even if errors occur
  • -v verbose, show objects processed

how to use chmod

chmode u+rwx, g+rw-, o+r-- desired_file
# number system
chmod 764 desired_file

resources

linux, os, cli