PHP's mkdir() function creates a safer permission setting method for folders, _PHP tutorial

php’s mkdir() function is a safer way to set permissions when creating a folder,

Problem description:
A directory is created using the following php code. The expected permission of the directory is 0777, and the actual result is 0755

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.

For example, the default umask of Linux is generally 0022, that is, the default permission to create a directory is 0755, so at this time php mkdir('./aa/',0777) gets the permission of the directory to be 0755.

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

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

Summary:

If php wants to create a directory with read and write permissions, it is best to use the following code. Do not directly use the mkdir function to specify permissions to avoid the impact of system umask