file ownership

File ownership is managed by a user owner and a group owner. See ls -l or ls -n

Examples:

chown user:group file #change owner and group
chown user file # change only owner
chown :group file #change only group, same as chgrp command

Linux POSIX rights

POSIX is a standard.

List rights

ls -l

Type codes:

• -: file
• d: folder
• l: symlink
• p: pipe. used to make 2 programs communicate
• s: socket. used to make 2 programs communicate + network management + bidirectional
• b: block device, ie write block by block
• c: character device, ie write char by char

9 bits: 3 User + 3 Group + 3 Other

chmod

• u: for user
• g: for group
• o: for others

• a: for all

• +: add right

• -: remove right

• =: set right

• r: read. 2^2 => 4

• w: write.2^1 => 2

• x: execute.2^0 => 1

  chmod u+r,g-r file.txt chmod a=rwx file.txt chmod 740 file.txt