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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-19 15:01:58 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-19 15:01:58 +0000 |
| commit | 54b6467013bfbdb3ee606961c02fbff1271ca582 (patch) | |
| tree | e3969743e61542979f12fca01017e67c4480eca8 /doc/s6-hiercopy.html | |
| download | s6-linux-utils-54b6467013bfbdb3ee606961c02fbff1271ca582.tar.xz | |
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diff --git a/doc/s6-hiercopy.html b/doc/s6-hiercopy.html new file mode 100644 index 0000000..e8dd2ed --- /dev/null +++ b/doc/s6-hiercopy.html @@ -0,0 +1,66 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>s6-linux-utils: the s6-hiercopy program</title> + <meta name="Description" content="s6-linux-utils: the s6-hiercopy program" /> + <meta name="Keywords" content="s6 linux administration root utilities hiercopy cp -a" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6-linux-utils</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>s6-hiercopy</tt> program </h1> + +<p> +<tt>s6-hiercopy</tt> copies a directory structure recursively. +</p> + +<h2> Interface </h2> + +<pre> + s6-hiercopy <em>source</em> <em>destination</em> +</pre> + +<ul> + <li> <tt>s6-hiercopy</tt> recursively copies <em>source</em> to +<em>destination</em>, which is created if it doesn't exist. +The permissions are preserved. The owner and group are preserved +if the user is the superuser. </li> + <li> It exits 0 on success and 111 on temporary failure. </li> +</ul> + +<h2> Notes </h2> + +<p> + Copying files and browsing through directories is one of Unix's +weakest points, and <tt>s6-hiercopy</tt> is not meant to work around +the problem; it's only a quick hack that I needed to boot my embedded +platform. I originally planned to write the ultimate <tt>cp</tt> utility, +portable and reliable and featureful and everything - while needing +approximately a hundred times less resources than GNU <tt>cp</tt> does, +of course. But I eventually dropped the idea: it's just impossible to +design, much less write, such a utility. +</p> + +<ul> + <li> You can't make it portable because there's no universal standard. +There is no portable way of creating device special files, for instance. +So <tt>s6-hiercopy</tt> appears here instead of in +<a href="http://skarnet.org/software/s6-portable-utils/">s6-portable-utils</a>: +the platform where I needed that kind of tool is Linux. </li> + <li> You can't make it reliable because Unix's set of filesystem +management primitives is just too weak. It lacks a lot of atomic +operations, and filesystem transactions. As a result, <tt>s6-hiercopy</tt> +is a walking race condition and should <strong>absolutely not</strong> +be considered instant when used in a multitasking environment. +But then, <tt>cp -a</tt> shouldn't either. </li> +</ul> + +</body> +</html> |