r Read 4
w write 2
1 x execution
u: file owner
g: Owned by group
o: others
a: Everyone
1.chmod
Format: chmod permissions filename
chmod -R directory: permission to modify directories and directory files
parameter:
-c output debugging information when changes
-f Do not display an error message
-R processing specified directory and all files in subdirectories
-V displays detailed process information Runtime
2.chgrp modify the file belongs to the group: chgrp group file name belongs options
3.chown modify their user: chown username filename option
Note: chown -R username: Group file name