The mkdir of function of php creates a safe permission setting method for folders

Problem description:
Using the following php code, 1 directory was created, and the expected directory permission was 0777, but the actual result was 0755

mkdir('./aa/',0777);

Analysis and test results:

1. The directory permissions specified by the mkdir () function can only be less than or equal to the default permissions set by the system umask.

Like linux default umask1 0022, that is, the default permission to create a directory is 0755, so php mkdir ('./aa/', 0777) gets a directory with 0755 permission.

xw@xw-X201:~/Desktop/dd/aa$ umask

0022

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw/',0777);"

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw1/',0755);"

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw2/',0747);"

xw@xw-X201:~/Desktop/dd/aa$ ll

 Total dosage  20

drwxrwxrwx 5 xw xw 4096 2012-06-01 11:58 ./

drwxr-xr-x 6 xw xw 4096 2012-06-01 11:26 ../

drwxr-xr-x 2 xw xw 4096 2012-06-01 11:57 xw/

drwxr-xr-x 2 xw xw 4096 2012-06-01 11:58 xw1/

drwxr--r-x 2 xw xw 4096 2012-06-01 11:58 xw2/

Change the system default permission to 777, and mkdir () can specify larger permissions

xw@xw-X201:~/Desktop/dd/aa$ umask 000

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw2/',0777);"

xw@xw-X201:~/Desktop/dd/aa$ ll

 Total dosage  12

drwxrwxrwx 3 xw xw 4096 2012-06-01 12:08 ./

drwxr-xr-x 6 xw xw 4096 2012-06-01 11:26 ../

drwxrwxrwx 2 xw xw 4096 2012-06-01 12:08 xw2/

2. The chmod () function is not affected by the system umask, and can set permissions larger than the system default permissions.

xw@xw-X201:~/Desktop/dd/aa$ umask

0022

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw1/',0777);"

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw2/');"

xw@xw-X201:~/Desktop/dd/aa$ php -r "mkdir('./xw3/');chmod('./xw3/',0777);"

xw@xw-X201:~/Desktop/dd/aa$ ll

 Total dosage  20

drwxrwxrwx 5 xw xw 4096 2012-06-01 12:12 ./

drwxr-xr-x 6 xw xw 4096 2012-06-01 11:26 ../

drwxr-xr-x 2 xw xw 4096 2012-06-01 12:11 xw1/

drwxr-xr-x 2 xw xw 4096 2012-06-01 12:11 xw2/

drwxrwxrwx 2 xw xw 4096 2012-06-01 12:12 xw3/

3. The mkdir command of the system can set permissions greater than the default value.

xw@xw-X201:~/Desktop/dd/aa$ umask

0022

xw@xw-X201:~/Desktop/dd/aa$ mkdir -m0777 xw

xw@xw-X201:~/Desktop/dd/aa$ ll

 Total dosage  12

drwxrwxrwx 3 xw xw 4096 2012-06-01 12:18 ./

drwxr-xr-x 6 xw xw 4096 2012-06-01 11:26 ../

drwxrwxrwx 2 xw xw 4096 2012-06-01 12:18 xw/

　　

Summary:

php If you want to create a directory with read and write permissions, it is best to use the following code, and do not directly use the mkdir function to specify permissions to avoid the influence of the system umask

mkdir('./xw/');

chmod('./xw/',0777);