What is meant by UMASK

[Dwarner]

Hi,,,

I have a very small query. Regarding to my younger brother's studies that need to work on Unix file permissions, he got a confusing word that is UMASK. Now i also heard this word for the first time.

Could you guys please make me know what is meant by UMASK ? Thanks in advance.

[MrChris-]

UMASK is a command and a function in POSIX environments that sets the file mode creation mask of the current process. It is a Unix environment variable which automatically sets file permissions on newly created files.

UMASK is a four-digit octal number that can be used to control the default file permission for new files. umask() sets PHP's umask to mask & 0777 and returns the old umask. When PHP is being used as a server module, the umask is restored when each request is finished.

[jesse]

Umask sets the mask applied to newly created file and directory permissions within a given context. It specifies the permissions you do not want given by default to newly created files and directories. umask works by doing a bitwise AND with the bitwise complement of the umask. Bits that are set in the umask correspond to permissions that are not automatically assigned to newly created files.The UMASK variable can be confusing to use, because it does work as a mask. In other words, you set the permissions that you do not want in the UMASK.

[Dr. V]

UMASK only restricts permissions and cannot grant extra permissions beyond what is specified by the program that creates the file or directory.You can setup umask in /etc/bashrc or /etc/profile file for all users. umask() without arguments simply returns the current umask otherwise the old umask is returned.By default, the Umask in the server configuration, <VirtualHost> or <Anonymous> block is used, unless overridden by a "per-directory" Umask setting.