LINUX2.4CHOMD, Chown, umask

File or directory Permissions chmod

Each file or directory has its own permissions. If starting from the second column nine permission bits, divided into three segments. R=4 w=2 x=1, respectively, can be expressed in numbers. Rwx=7 rw-=6--x=1 rw-r--r--=644

[Email protected] tmp]# ls-l 1.txt-rw-r--r--. 1 root root 0 October 06:08 1.txt[[email protected] tmp]# rw-r--r--=600^c[[email protected] tmp]# chmod 666 1.txt[[email PR Otected] tmp]#!lls-l 1.txt-rw-rw-rw-. 1 root root 0 October 06:08 1.txt

We can see that there is a point behind the nine permission bits. Note that this file is subject to SELinux, and if SELinux is turned on, the file created has such a point.

[[email protected] tmp]# Getenforcedisabled[[email protected] tmp]# touch 3.txt[[email protected] tmp]# ls-l 3.txt-rw-r-- r--1 root root 0 October 06:15 3.txt

When SELinux is closed, it is not identified by this dot.

Bulk Modify Permissions-R

[Email protected] tmp]# chmod 777 chy         #修改目录权限 [[email protected] tmp]# ls-l./chy/1.txt           #  The file permissions within the directory have not been modified-rw-r--r--1 root root 0 October 06:18/chy/1.txt[[email protected] tmp]# ls-ld chy/                   #目录权限变化drwxrwxrwx 2 Root root 18 October 06:18 chy/[[email protected] tmp]# chmod-r 770 chy         #-r Bulk Modify the directory and all of the following permissions [[email protected] tmp]# ls -L chy/Total dosage 0-rwxrwx---1 root root 0 October 06:18 1.txt[[email protected] tmp]# ls-ld chy/drwxrwx---2 root root 18 October 2 5 06:18 chy/

U g o A, you can + = with a minus sign should be noted, must have this permission bit, such as rw--X this is not standard.

[[email protected] tmp]# chmod u+x,g+w,o=r chy[[email protected] tmp]# chmod a+x chy[[email protected] tmp]# chmod a-x chy

Change owner and owning group Chown

[Email protected] tmp]# ls-l 1.txt-rw-rw-rw-. 1 root root 0 October 06:08 1.txt[[email protected] tmp]# chown chy002 1.txt          #更改所有者 [[email protected] tmp]# ls-l 1.txt -rw-rw-rw-. 1 chy002 Root 0 October 06:08 1.txt[[email protected] tmp]# chgrp chy002 1.txt            #更改所属组 [[email protected] tmp]#!lls-l 1 . txt-rw-rw-rw-. 1 chy002 chy002 0 October 06:08 1.txt

Where chown can also change the owning group.

[[email protected] tmp]# chown chy002:user chy/[[email protected] tmp]# ls-ld chy/drw-rw-r--2 chy002 user 18 October 25 06:1 8 chy/

-R can modify the relationship of all files under the file

[[email protected] tmp]# chown-r user:chy002/tmp/chy/[[email protected] tmp]# ls-ld chydrw-rw-r--2 user chy002 18 October 06:18 Chy[[email protected] tmp]# ls-ls chy/1.txt0-rwxrwx---1 user chy002 0 October 06:18 chy/1.txt

Umask

By default, directory permissions are 755, and normal file permissions are 644. This value is determined by umask. If you do not have X permissions, the directory is not able to open browsing.

[[email protected] tmp]# mkdir chy2[[email protected] tmp]# touch Chy2.txt[[email protected] tmp]# ls-lst Total usage 40-rw-r--r- -  1 root   root     0 October 06:45 chy2.txt0 drwxr-xr-x  2 root   root     6 October 06:45 chy2

If the user is created as a normal file, the default is no executable permission. Only RW has two permissions, up to a maximum of 666.

If the user is set up as a directory, the maximum permission is 777.

Don't use numbers to directly reduce umask. What if Umask is 003?

rwxrwxrwx--------WX = rwxrwxr--vacancy minus x is still empty.

Umask can go to config file/ETC/BASHRC modify

LINUX2.4CHOMD, Chown, umask