1. decoding
When we use the ls -l command to view file similar specific information, we can see that Linux files are displayed in the following form:
drwxr--r-- root root ...What does it mean? How to resolve this string of identity?
Firstly, that identifies the file permissions drwxr - r-- string, the head of the d identifies the type of the file, Linux file types identified as follows:
（1）-：普通文件
（2）d：目录
（3）c：字符设备文件
（4）b：块设备文件
（5）l：链接文件
（6）s：本地域套接口 (socket)
（7）p：有名管道 (pipeline)After removal of the first file type identification, and the rest rwxr - r-- , which each have four optional identifier represents, respectively, as follows:
1. r：读权限
2. w：写权限
3. x：文件执行权限
4. -：无对应权限It will be divided into 3 parts, respectively rwx r-- r-- , each part respectively:
-
- Owned by user (user) privileges
-
- Owned by group (group) rights
-
- Other users (other) authority
For the above permission to do the following explanation:
- Owned by user (root) have R & lt (read), w (write), x (execute) permissions
- Owned by group (root) have R & lt (read) authority
- R & lt owned by another user (read) authority
2. coding
File permissions identifier may be encoded as a decimal integer 3
EG. Rwx r-- r-- using the following encoding algorithm:
The sections are calculated. First, the first portion rwx terms, which represent three binary-coded bit, a first bit is readable identification (R & lt), whether the second identification bit writable (w), the third identifier is executable (x).
The value of each bit, 1 means enable, on the contrary represents 0 Unable, thus rwx the binary representation 111 , it is to decimal 7 .
Also for the two portions r-- r-- , which are binary coded 100 100 , respectively coded decimal 44 , thus identifying the file permissions rwx r-- r-- decimal coded as 744 .
3. Use
Coded decimal file permissions may be used in the identification chmod command may be used chmod -R 755 DirectoryName form of authorization to all files in the folder 755 , i.e. rwxrw-rw- .