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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-18 20:03:23 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-18 20:03:23 +0000 |
| commit | f316a2ed52195135a35e32d7096e876357c48c69 (patch) | |
| tree | 5f4486b9a5a213a69e66ef574d6bc643a207981c /doc/shift.html | |
| download | execline-f316a2ed52195135a35e32d7096e876357c48c69.tar.xz | |
initial commit: rc for execline-2.0.0.0
Diffstat (limited to 'doc/shift.html')
| -rw-r--r-- | doc/shift.html | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/doc/shift.html b/doc/shift.html new file mode 100644 index 0000000..775e472 --- /dev/null +++ b/doc/shift.html @@ -0,0 +1,68 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>execline: the shift program</title> + <meta name="Description" content="execline: the shift program" /> + <meta name="Keywords" content="execline command shift" /> + <!-- <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/">www.skarnet.org</a> +</p> + +<h1> The <tt>shift</tt> program </h1> + +<p> +<tt>shift</tt> shifts the positional parameters of an execline script. +</p> + +<h2> Interface </h2> + +<pre> + shift [ -n <em>argn</em> ] [ -b <em>blockn</em> ] <em>prog...</em> +</pre> + +<ul> + <li> <tt>shift</tt> shifts <em>argn</em> positional parameters, +then <em>blockn</em> blocks. It then execs <em>prog...</em>. </li> + <li> By default, <em>argn</em> and <em>blockn</em> are both zero; +but if neither the <tt>-n</tt> nor the <tt>-b</tt> option is given, +then <em>argn</em> is 1 and <em>blockn</em> is 0. </li> +</ul> + +<h2> Details </h2> + +<ul> + <li> <tt>shift</tt> reads the number of "positional parameters" in the +<tt>#</tt> environment variable. Let <em>n</em> be that number. </li> + <li> If the <tt>#</tt> environment variable is not set or does not +contain a valid number, or one of the <tt>0</tt>, <tt>1</tt>, ..., +<tt><em>n</em></tt> environment variables is not set, <tt>shift</tt> +exits 100 with an error message. </li> + <li> <tt>shift</tt> calculates a shift value <em>m</em>, corresponding +to <em>argn</em> arguments followed by enough arguments to make +<em>blockn</em> blocks. </li> + <li> It shifts the positional parameters <em>m</em> times: the +value of the <tt><em>m</em>+1</tt> variable becomes the value of the +<tt>1</tt> variable, <tt><em>m</em>+2</tt> becomes <tt>2</tt> and so on, +and <tt>#</tt> is set to <em>n</em>-<em>m</em> (floored at zero). </li> + <li> <tt>shift</tt> then execs into <em>prog...</em>. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> <tt>shift</tt> is a standard shell builtin. Be careful if you +want to use it outside of an execline script. </li> + <li> The <tt>-b</tt> option is only useful to implement execline +commands in the execline language. You shouldn't normally have to +use it. </li> +</ul> + +</body> +</html> |