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diff --git a/doc/case.html b/doc/case.html new file mode 100644 index 0000000..5340c07 --- /dev/null +++ b/doc/case.html @@ -0,0 +1,93 @@ +<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 case command</title> + <meta name="Description" content="execline: the case command" /> + <meta name="Keywords" content="execline command case regex grep" /> + <!-- <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>case</tt> program </h1> + +<p> +<tt>case</tt> compares a value against a series of regular expressions, +and executes into a program depending on the first expression the value +matches. +</p> + +<h2> Interface </h2> + +<p> + In an <a href="execlineb.html">execlineb</a> script: +</p> + +<pre> + case [ -E | -e | -i | -n ] <em>value</em> + { + [ regex { <em>prog...</em> } ] + [ regex { <em>prog...</em> } ] + ... + } + <em>progdefault...</em> +</pre> + +<ul> + <li> <tt>case</tt> reads an argument <em>value</em> and a sequence of +directives in a <a href="el_semicolon.html">block</a>. </li> + <li> Each directive is a regular expression followed by a block. </li> + <li> <tt>case</tt> matches <em>value</em> against the regular expressions +in the order they are given. </li> + <li> As soon as <em>value</em> matches a <em>regex</em>, <tt>case</tt> +executes into the <em>prog...</em> command line that immediately follows +the matched regex. </li> + <li> If <em>value</em> matches no <em>regex</em>, <tt>case</tt> +eventually execs into <em>progdefault...</em>. </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-e</tt> : Interpret the <em>regex</em> words as +<a href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03">basic +regular expressions</a>. </li> + <li> <tt>-E</tt> : Interpret the <em>regex</em> words as +<a href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04">extended +regular expressions</a>. This is the default. </li> + <li> <tt>-i</tt> : Perform case-insensitive matches. </li> + <li> <tt>-n</tt> : Do not transmit the matching expression and +subexpressions to <em>prog...</em> via the environment. This is the default. </li> + <li> <tt>-N</tt> : Make the matching expression and +subexpressions available to <em>prog</em>'s environment. </li> +</ul> + +<h2> Subexpression matching </h2> + +<p> + If the <tt>-N</tt> option has been given, and <em>value</em> matches a <em>regex</em>, +then <tt>case</tt> will run <em>prog</em> with a modified environment: +</p> + +<ul> + <li> The <tt>0</tt> variable will contain the <em>regex</em> that <em>value</em> matched. </li> + <li> The <tt>#</tt> variable will contain the number of subexpressions in <em>regex</em>. </li> + <li> For every integer <em>i</em> between 1 and the number of subexpressions (included), the +variable <em>i</em> contains the part of <em>value</em> that matched the <em>i</em>th subexpression +in <em>regex</em>. </li> +</ul> + +<p> + To retrieve that information into your command line in an execline script, you can use the +<a href="elgetpositionals.html">elgetpositionals</a> program. +</p> + +</body> +</html> |