How can I get octal file permissions from command line?

Question

There is a chmod command to set file permissions, but can I get file permissions in octal mode (such as 755) from the command line?

Answer 1

You can try

stat -c "%a %n" *

Replace * with the relevant directory or the exact filename that you want to examine.

From the man page of stat,

-c  --format=FORMAT
          use  the  specified  FORMAT instead of the default; output a newline after
          each use of FORMAT
%a     Access rights in octal
%n     File name

Usage:

• With files:

  $ stat -c "%a %n" ./Documents/Udev.html 
  664 ./Documents/Udev.html
  

• With folders:

  $ stat -c "%a %n" ./Documents/
  755 ./Documents/
  

(Reference)

Answer 2

File permissions in Linux can be displayed in octal format using Linux stat command.

Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, Navigate to the directory where you want to find the file permissions in octal mode.

stat -c '%A %a %n' *

%A Access rights in human readable form

%a Access rights in octal

%n File name

Octal numbers and permissions

You can use octal number to represent mode/permission:

r: 4
w: 2
x: 1

For example, for file owner you can use octal mode as follows. Read, write and execute (full) permission on a file in octal is 0+r+w+x = 0+4+2+1 = 7

Only Read and write permission on a file in octal is 0+r+w+x = 0+4+2+0 = 6

Only read and execute permission on a file in octal is 0+r+w+x = 0+4+0+1 = 5

Use above method to calculate permission for group and others. Let us say you wish to give full permission to owner, read & execute permission to group, and read only permission to others, then you need to calculate permission as follows: User = r+w+x = 0+4+2+1 = 7 Group= r+w+x = 0+4+2+0 = 6 Others = r+w+x = 0+0+0+1 = 1

Effective permission is 761.

Source: http://kmaiti.blogspot.com/2011/09/umask-concept.html

Answer 3

As detailed here, you can create an alias lso that acts like ls -l but displays permissions also in octal.

alias lso="ls -alG | awk '{k=0;for(i=0;i<=8;i++)k+=((substr(\$1,i+2,1)~/[rwx]/)*2^(8-i));if(k)printf(\" %0o \",k);print}'"