In Unix-like operating systems, /dev/null or the null device is a special file that discards all data written to it (but reports that the write operation succeeded) and provides no data to any process that reads from it (yielding EOF immediately).^[1]

In programmer jargon, especially Unix jargon, it may also be called the bit bucket^[2] or black hole.

Usage [link]

The null device is typically used for disposing of unwanted output streams of a process, or as a convenient empty file for input streams. This is usually done by redirection.

/dev/null is a special file, not a directory, so one cannot move a whole directory into it with the Unix mv command. The rm command is the proper way to delete files in Unix.

This concept is roughly equivalent to the NUL: or just NUL device of CP/M, DOS and Windows, the \Device\Null or NUL of Windows NT and its successors, the NIL: of Amiga operating systems, and the NL: of OpenVMS. In Windows Powershell, the equivalent is $null.

References in computer culture [link]

This entity is a common inspiration for technical jargon expressions and metaphors by Unix programmers, e.g. "please send complaints to /dev/null", "my mail got archived in /dev/null", and "redirect to /dev/null"—being jocular ways of saying, respectively: "don't bother sending complaints", "my mail was deleted", and "go away".^[3] The iPhone Dev Team commonly uses the phrase "send donations to /dev/null", meaning they do not accept donations. The fictitious person name "Dave (or Devin) Null" is sometimes similarly used (e.g., "send complaints to Dave Null").^{[citation needed]}

The null device is also a favorite subject of technical jokes, such as warning users that the system's /dev/null is already 98% full. The April Fool's, 1995 issue of the German magazine c't reported on an enhanced /dev/null chip that would efficiently dispose of the incoming data by converting it to a flicker on an internal glowing LED.

See also [link]

• Filesystem Hierarchy Standard
• Memory hole
• rm (Unix)
• Standard streams
• /dev
• Unix philosophy
• Write-only memory

References [link]