blob: 6aa2f01cbb5f4f1735a27114f5163725ed27db25 (
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
|
<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>execline: the backtick command</title>
<meta name="Description" content="execline: the backtick command" />
<meta name="Keywords" content="execline command backtick" />
<!-- <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>backtick</tt> program </h1>
<p>
<tt>backtick</tt> runs a program and stores its output in an
environment variable, then executes another program.
</p>
<h2> Interface </h2>
<p>
In an <a href="execlineb.html">execlineb</a> script:
</p>
<pre>
backtick [ -i | -D <em>default</em> ] [ -n ] <em>variable</em> { <em>prog1...</em> } <em>prog2...</em>
</pre>
<ul>
<li> <tt>backtick</tt> reads <em>prog1...</em> in a
<a href="el_semicolon.html">block</a> and unquotes it. </li>
<li> It runs <em>prog1...</em> as a child process and saves its
output in memory. This output must not contain a null character. </li>
<li><tt>backtick</tt> execs into the modified <em>prog2...</em>, with
<em>variable</em> added to the environment with <em>prog1...</em>'s
output as a value. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-i</tt> : insist. If <em>prog1</em> crashes or exits non-zero,
<tt>backtick</tt> exits with an
<a href="exitcodes.html">approximation</a> of the same exit code. </li>
<li> <tt>-D <em>default</em></tt> : default value. If
<em>prog1</em> crashes or exits non-zero, <em>default</em> is used as
<em>variable</em>'s value. If neither the <tt>-i</tt> nor the <tt>-D</tt>
option have been given, <tt>backtick</tt> execs into
<em>prog2...</em> no matter what <em>prog1</em> does, with the null word as
<em>variable</em>'s value if <em>prog1</em> didn't write anything before
dying. </li>
<li> <tt>-n</tt> : chomp an ending newline off <em>prog1...</em>'s
output. </li>
</ul>
<h2> Notes </h2>
<ul>
<li> You can start <em>prog2...</em> with "import -u <em>variable</em>"
to perform variable substitution. </li>
</ul>
</body>
</html>
|
