Unix Permission

tux@tux-MS-7797:~$ mkdir /tmp/demo
tux@tux-MS-7797:~$ cd /tmp/demo
tux@tux-MS-7797:/tmp/demo$ mkdir folder
tux@tux-MS-7797:/tmp/demo$ touch folder/file
tux@tux-MS-7797:/tmp/demo$ chmod ugo+rwx folder/file
tux@tux-MS-7797:/tmp/demo$ chmod ugo-w folder
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$ ls -l
total 0
dr-xr-xr-x 1 tux tux 8 Jun 23 13:23 folder
tux@tux-MS-7797:/tmp/demo$ ls -l folder
total 0
-rwxrwxrwx 1 tux tux 0 Jun 23 13:23 file
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$ rm folder/file
rm: cannot remove 'folder/file': Permission denied
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$ chmod ugo+w folder
tux@tux-MS-7797:/tmp/demo$ sudo chown root folder/file
tux@tux-MS-7797:/tmp/demo$ sudo chgrp root folder/file
tux@tux-MS-7797:/tmp/demo$ sudo chmod ugo-rwx folder/file
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$ ls -l
total 0
drwxrwxrwx 1 tux tux 8 Jun 23 13:23 folder
tux@tux-MS-7797:/tmp/demo$ ls -l folder/
total 0
---------- 1 root root 0 Jun 23 13:23 file
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$
tux@tux-MS-7797:/tmp/demo$ rm folder/file
rm: remove write-protected regular empty file 'folder/file'? y
tux@tux-MS-7797:/tmp/demo$