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 name="viewport" content="width=device-width, initial-scale=1.0" />
<meta name="color-scheme" content="dark light" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<meta http-equiv="Content-Language" content="en" />
<title>execline: the cd command</title>
<meta name="Description" content="execline: the cd command" />
<meta name="Keywords" content="execline command cd chdir cd" />
<!-- <link rel="stylesheet" type="text/css" href="//skarnet.org/default.css" /> -->
</head>
<body>
<p>
<a href="index.html">execline</a><br />
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
</p>
<h1> The <tt>cd</tt> program </h1>
<p>
<tt>cd</tt> changes the current working directory to a
given directory, then executes a program.
</p>
<h2> Interface </h2>
<pre>
cd <em>dir</em> <em>prog...</em>
</pre>
<p>
<tt>cd</tt> performs a
<a href="https://pubs.opengroup.org/onlinepubs/9799919799/functions/chdir.html">chdir()</a>
system call on <em>dir</em>, then execs into <em>prog...</em>.
</p>
<h2> Notes </h2>
<ul>
<li> This <tt>cd</tt> program will never be invoked by a shell, unless its full path
is explicitly given to the shell command line. So it is perfectly acceptable and valid
to have a <tt>cd</tt> binary in the filesystem. No confusion will be possible: shells
will invoke their builtin
<a href="https://pubs.opengroup.org/onlinepubs/9799919799/utilities/cd.html">cd</a>
utility, and execline scripts will invoke the <tt>cd</tt> binary. </li>
<li> Previous versions of POSIX also required a conformant <tt>cd</tt> binary to exist
in the filesystem, for no reason at all. So, in previous execline versions,
a <tt>posix-cd</tt> binary was present, and <tt>cd</tt> could be installed as a symlink
to it when execline was configured with the <tt>--enable-pedantic-posix</tt> option.
This allowed distributions to make execline binaries, including <tt>cd</tt>, available
in PATH, while strictly conforming to POSIX. This requirement has now been relaxed by
POSIX, so the needlessly complex <tt>posix-cd</tt> program was replaced with this
simpler <tt>cd</tt>, that can now be made available in PATH without breaking strict
conformance. </li>
</ul>
</body>
</html>
|
