/dev/null is a character device file on UNIX
computer operating systems that accepts all data written to it, without storing it. It can be opened by many processes simultaneously, and writing to it doesn't cause the file to grow. Formally, it's described as being an infinite data sink. In shell programming, unwanted output from a command can be redirected there. For example:
find / 2>/dev/null
This would display the full paths to all the accessible files on the
computer, without displaying the "Permission denied" errors that are likely to occur.
When programs try to read from /dev/null, they get an end-of-file error.
The idea of a null device was imitated by Microsoft in MS-DOS. In DOS, 'NUL' is a reserved filename. When you open a file with that name, DOS opens its equivalent of /dev/null. This behavior was inherited by
Windows. In
Windows,
even versions of it that are based on the NT kernel, you cannot create a file called "NUL".
It is usually pronounced as "dev null", not "
slash dev,
slash null." Programmers sometimes refer to /dev/null as a place to send any unwanted information, even if, for example, the data is being transmitted as spoken
words from a human's mouth.
