blob: 1cce1b7d1902a5360f3b40d3f6702d81d833de02 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
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">bcnm</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>
|
