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Analysis of permission issues of mkdir() function in php
- 高洛峰Original
- 2016-12-21 15:14:061013browse
Problem description:
Use the following php code to create a directory. The expected directory permission is 0777, and the actual result is 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.
For example, the default umask of Linux is generally 0022, that is, the default permission for creating a directory is 0755, so at this time php mkdir('./aa/',0777) gets the permission of the directory to be 0755.
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 总用量 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/
Set the system default The permissions are changed to 777, and mkdir() can specify greater 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 总用量 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.chmod() function is not affected by the system umask and can set permissions greater 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 总用量 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 system’s mkdir command 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 总用量 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 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
mkdir('./xw/'); chmod('./xw/',0777);
More mkdir in php For related articles on the analysis of permission issues of () function, please pay attention to the PHP Chinese website!