chmod common usage

1 features

Change the access rights of the file. Mainly read, write, execute permissions.

2 Description 2.1 Types of permissions

R Read

W Write

X execute (or access to the directory)

x Append x attribute only if the target file is executable to some users or the target file is a directory

s set user or group ID at the same time

t sticky bit (delete or move)

2.2 Digital Permissions

Permissions can be replaced by four-bit octal digits, which are represented by:

First: 4 is suid, the file runs as the owner, 2 is Sgid, only the directory is set, the newly created file in the directory has the default setting of suid;1 as the sticky bit, which is understood as delete permission.

Second bit: Set permissions for the file owner.

Third bit: Set permissions for the group where the file owner resides.

Fourth bit: Set permissions for other group users.

2.3 Permission Objects

The owner of the U file

G users in the same group as the file owner

o Other groups of users

A All Users =ugo

2.4 operator

+ Add Permissions

-Delete Permissions

3 Common usage 3.1 Add File execution permissions to yourself

chmod u+x File

The difference from chmod file is that the latter clears other permissions, in addition to the EXECUTE permission.

3.2 Adding directories (and subdirectories) to everyone access permissions

Chmod-r +r File

3.3 Clear All permissions

CHMOD-RWXSTX file

Equivalent to chmod file

chmod common usage