blob: 91e9fb1b00d4fe3fffeeac29af3dfcdc9a294c5a (
plain) (
blame)
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
|
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="Content-Language" content="en" />
<title>execline: the loopwhilex command</title>
<meta name="Description" content="execline: the loopwhilex command" />
<meta name="Keywords" content="execline command loopwhilex" />
<!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> -->
</head>
<body>
<p>
<a href="index.html">execline</a><br />
<a href="http://skarnet.org/software/">Software</a><br />
<a href="http://skarnet.org/">skarnet.org</a>
</p>
<h1> The <tt>loopwhilex</tt> program </h1>
<p>
<tt>loopwhilex</tt> performs a conditional loop.
</p>
<h2> Interface </h2>
<pre>
loopwhilex [ -n ] [ -x <em>exitcodes</em> ] <em>prog...</em>
</pre>
<ul>
<li> <tt>loopwhilex</tt> runs <em>prog...</em> as a child process and
waits for it to complete. </li>
<li> As long as <em>prog</em> exits zero, <tt>loopwhile</tt> runs it again. </li>
<li> <tt>loopwhilex</tt> then exits 0. If <em>prog</em> was killed by a signal,
<tt>loopwhilex</tt> exits that signal's number instead. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-x</tt> <em>exitcodes</em> : <em>exitcodes</em> must be a comma-separated
list of valid exit codes. If this option is given, <tt>loopwhilex</tt> will run
<em>prog...</em> as long as its exit code is <em>not</em> listed in <em>breakcodes</em>. </li>
<li> <tt>-n</tt> : negate the test: run <em>prog...</em> as long as it exits non-zero
(or exits a code that <em>is</em> listed in <em>breakcodes</em>). </li>
</ul>
<h2> Notes </h2>
<ul>
<li> <tt>loopwhilex <em>prog</em>...</tt> is equivalent to <tt>loopwhilex -n -x 0 <em>prog...</em></tt>. </li>
<li> Be careful: execline <strong>maintains no state</strong>, in particular it
uses <strong>no real variables</strong>, and environment will
be of no use here since every instance of <em>prog...</em> runs as a separate
child process. To avoid being stuck in an infinite loop, <em>prog...</em>
should modify some external state - for instance, the filesystem. </li>
</ul>
</body>
</html>
|
