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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2020-02-11 01:38:05 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2020-02-11 01:38:05 +0000 |
| commit | 48a5bb7a26de6c3bea32d18c3e476dd2cedbcfd3 (patch) | |
| tree | fbed694d378457ac473e5ba93eca47470723f173 /doc/bcnm-waitif.html | |
| parent | 55bc8fead207fcb2aafe414ce84073f147ebce39 (diff) | |
| download | bcnm-48a5bb7a26de6c3bea32d18c3e476dd2cedbcfd3.tar.xz | |
Add bcnm-waitif doc
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diff --git a/doc/bcnm-waitif.html b/doc/bcnm-waitif.html new file mode 100644 index 0000000..ac95397 --- /dev/null +++ b/doc/bcnm-waitif.html @@ -0,0 +1,87 @@ +<html> + <head> + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>bcnm: the bcnm-waitif program</title> + <meta name="Description" content="bcnm: the bcnm-waitif program" /> + <meta name="Keywords" content="bcnm waitif interface state up running flag notification netlink" /> + <!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">s6</a><br /> +<a href="//skarnet.org/software/">Software</a><br /> +<a href="//skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>bcnm-waitif</tt> program </h1> + +<p> +<tt>bcnm-waitif</tt> waits until a set of network interfaces are in the desired state, +or a timeout occurs. Then it exits. It is typically used to avoid race conditions +in a service startup sequence. +</p> + +<h2> Interface </h2> + +<pre> + bcnm-waitif [ -u | -d ] [ -t <em>timeout</em> ] [ -k <em>kbufsize</em> ] <em>mask</em> <em>interface...</em> +</pre> + +<ul> + <li> <tt>bcnm-waitif</tt> reads the state of all the interfaces specified by +name as the <em>interface...</em> arguments. </li> + <li> If all the listed interfaces match the state defined in <em>mask</em>, +it exits 0. </li> + <li> Else, it waits for network interface state changes, and performs the +check again. </li> + <li> It loops until all the listed interfaces are in the desired state, +or a timeout (if defined) occurs. </li> +</ul> + +<h2> <em>mask</em> meaning </h2> + +<p> + <em>mask</em> is an unsigned integer representing a bitmask for the +flags to be tested. If several bits are given, the wanted state is the +conjunction of these flags: the condition will be true if <em>all</em> +those checks pass. +</p> + +<ul> + <li> 1: the interface exists (the kernel knows about it) </li> + <li> 2: the interface is UP (the administrator has activated it) </li> + <li> 4: the interface is RUNNING (functional, not unplugged) </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-u</tt> : up. <tt>bcnm-waitif</tt> will wait until all +the states defined in <em>mask</em> are reached by all the interfaces +in <em>interface...</em>. This is the default. </li> + <li> <tt>-d</tt> : down. <tt>bcnm-waitif</tt> will wait until +<em>none</em> of the states defined in <em>mask</em> is true. </li> + <li> <tt>-t <em>timeout</em></tt> : if the desired state +still has not been reached after <em>timeout</em> milliseconds, +<tt>bcnm-waitif</tt> will exit 99 with an error message. The default +is 0, meaning there is no timeout and the program can wait forever. </li> + <li> <tt>-k <em>kbufsize</em></tt> : use <em>kbufsize</em> +bytes for the netlink socket buffer. Too small a buffer risks losing +state change events and reporting incorrect results. Too large a buffer +wastes memory. Default is 131072, which is probably on the large side. </li> +</ul> + +<h2> Exit codes </h2> + +<ul> + <li> 0: success </li> + <li> 99: timed out </li> + <li> 100: wrong usage </li> + <li> 111: system call failed </li> +</ul> + +</body> +</html> |