Devnullとは 意味・読み方・使い方

語源

From Unix operating systems, where /dev (the Unix directory containing device files) contains a null entry representing no device.

固有名詞

/dev/null

1. (computing) A device file, present in Unix and Unix-like operating systems, that discards all data written to it and yields no output, always being as an empty file when read.

   It's possible to suppress the compiler's warnings by redirecting standard error to /dev/null.

   • 1980 October, Luis F. Cabrera, “A Performance Evaluation Study of UNIX”, in Harold Joseph Highland, editor, Computer Performance Evaluation Users Group 16th Meeting (National Bureau of Standards Special Publication; 500-65), Washington: Government Printing Office, page 235:

     To avoid problems when running the script, the output of man man was sent to /dev/null instead of sending it to a real terminal. This has the effect of discarding the already formatted text of the retrieved page.

   • 1993, Stephen A. Rago, UNIX System V Network Programming, Pearson, →ISBN, page 89:

     [...] we reserve file descriptors 0, 1, and 2 by opening /dev/null and duplicating the file descriptor returned. /dev/null is a pseudo-driver that forces read to return 0 and write to return as if the entire amount requested had been written. This makes library routines that use file descriptors 0, 1, and 2 harmless.

   • 2005, Eric Foster-Johnson with John C. Welch and Micah Anderson, Beginning Shell Scripting, John Wiley & Sons, →ISBN, page 263:

     Continuing in the Unix tradition of treating everything as a file, you can redirect a command's output to the null file, /dev/null. The null file consumes all output sent to it, as if /dev/null is a black hole star.

2. (Internet slang, figuratively) Nowhere; often suggests an intent to ignore specific correspondence.
   • 1992 September 17, Douglas Meier <dmeier@casbah.acns.nwu.edu>, “Welfare Reform Idea”, in talk.politics.misc‎ (Usenet), message-ID <1992Sep17.064757.551@news.acns.nwu.edu>:

     Thoughtful discussion and criticism is welcomed, but please send all flames to dev null.

   • 1993 December 18, Carmien Stefan <carmien@alumni.cs.Colorado.EDU>, “RLP hosed”, in alt.unix.wizards‎ (Usenet), message-ID :

     suddenly the RLP calls form atlanta apparently go to dev null.

   • 2004 January 17, Ronald D. Edge <InactiveX666@hotmail.com>, “PayPal pyramid scam”, in news.admin.net-abuse.email‎ (Usenet), message-ID :

     The email will explicitly state that you cannot reply to the email, it will go to dev null.

上位語

等位語

Further reading

• null device on Wikipedia.Wikipedia