Unix filesystem: Difference between revisions

Revision as of 11:48, 26 August 2010

Revision as of 15:41, 10 November 2010

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::*'''<tt>[[dev-null|/dev/null]]</tt>''' — also known as the "bit bucket" or "black hole", this [[pseudo device]] discards all contents written to it, and is typically used to pipe away unwanted data.

::* '''<tt>[[/dev/random]]</tt>''' — this pseudo device returns [[pseudorandom numbers]] (subject to the limitations of [[random number generator]]s in [[computing]]) when read from. It uses system noise to generate random numbers and blocks if not enough entropy in the noise is available. Random is commonly used by programs such as [[SSH]] that absolutely need cryptographically-strong random data such as [[SSH]] to generate an [[encryption]] key.

::* '''<tt>/dev/urandom</tt>''' — similar to <tt>/dev/random</tt>, except it always returns random numbers, even if there is not enough entropy in the system noise available.