From b9d8ecbc6a76779d0c63729a21628965cafcc4cc Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 7 Apr 2005 15:51:27 +0000 Subject: * More doc updates. --- doc/manual/nix-prefetch-url.xml | 113 +++++++++++++++++++++++----------------- 1 file changed, 64 insertions(+), 49 deletions(-) (limited to 'doc/manual/nix-prefetch-url.xml') diff --git a/doc/manual/nix-prefetch-url.xml b/doc/manual/nix-prefetch-url.xml index a6b3711e3..a0d5a97f1 100644 --- a/doc/manual/nix-prefetch-url.xml +++ b/doc/manual/nix-prefetch-url.xml @@ -1,54 +1,69 @@ - - nix-prefetch-url - copy a file from a URL into the store and print its MD5 hash - - - - - nix-prefetch-url - url - - - - - Description - - - The command nix-prefetch-url downloads the - file referenced by the URL url, - prints its MD5 cryptographic hash code, and copies it into the - Nix store. The file name in the store is - hash-basename, - where basename is everything - following the final slash in url. - - - - This command is just a convenience to Nix expression writers. - Often a Nix expressions fetch some source distribution from the - network using the fetchurl expression - contained in nixpkgs. However, - fetchurl requires an MD5 hash. If you don't - know the hash, you would have to download the file first, and - then fetchurl would download it again when - you build your Nix expression. Since - fetchurl uses the same name for the - downloaded file as nix-prefetch-url, the - redundant download can be avoided. - - - - - - Examples - - + + + nix-prefetch-url + copy a file from a URL into the store and print its MD5 hash + + + + + nix-prefetch-url + url + hash + + + + +Description + +The command nix-prefetch-url downloads the +file referenced by the URL url, prints its +cryptographic hash, and copies it into the Nix store. The file name +in the store is +hash-baseName, +where baseName is everything following the +final slash in url. + +This command is just a convenience for Nix expression writers. +Often a Nix expression fetches some source distribution from the +network using the fetchurl expression contained in +Nixpkgs. However, fetchurl requires a +cryptographic hash. If you don't know the hash, you would have to +download the file first, and then fetchurl would +download it again when you build your Nix expression. Since +fetchurl uses the same name for the downloaded file +as nix-prefetch-url, the redundant download can be +avoided. + +The environment variable NIX_HASH_ALGO specifies +which hash algorithm to use. It can be either md5, +sha1, or sha256. The default is +md5. + +If hash is specified, then a download +is not performed if the Nix store already contains a file with the +same hash and base name. Otherwise, the file is downloaded, and an +error if signaled if the actual hash of the file does not match the +specified hash. + +This command prints the hash on standard output. Additionally, +if the environment variable PRINT_PATH is set, the path +of the downloaded file in the Nix store is also printed. + + + + +Examples + + $ nix-prefetch-url ftp://ftp.nluug.nl/pub/gnu/make/make-3.80.tar.bz2 -... -file has hash 0bbd1df101bc0294d440471e50feca71 -... +0bbd1df101bc0294d440471e50feca71 + +$ PRINT_PATH=1 nix-prefetch-url ftp://ftp.nluug.nl/pub/gnu/make/make-3.80.tar.bz2 +0bbd1df101bc0294d440471e50feca71 +/nix/store/wvyz8ifdn7wyz1p3pqyn0ra45ka2l492-make-3.80.tar.bz2 + + - -- cgit v1.2.3