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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/if.html | |
| download | execline-f316a2ed52195135a35e32d7096e876357c48c69.tar.xz | |
initial commit: rc for execline-2.0.0.0
Diffstat (limited to 'doc/if.html')
| -rw-r--r-- | doc/if.html | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/doc/if.html b/doc/if.html new file mode 100644 index 0000000..2157a07 --- /dev/null +++ b/doc/if.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 if command</title> + <meta name="Description" content="execline: the if command" /> + <meta name="Keywords" content="execline command if" /> + <!-- <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>if</tt> program </h1> + +<p> +<tt>if</tt> performs conditional execution. +</p> + +<h2> Interface </h2> + +<p> + In an <a href="execlineb.html">execlineb</a> script: +</p> + +<pre> + if [ -X ] [ -n ] [ -t | -x <em>exitcode</em> ] { <em>prog1...</em> } <em>prog2...</em> +</pre> + +<ul> + <li> <tt>if</tt> reads <em>prog1...</em> in a +<a href="el_semicolon.html">block</a>. It forks and executes it, +then waits for it to complete. </li> + <li> If <em>prog1</em> crashes, <tt>if</tt> exits 1 with a special +error message. </li> + <li> If <em>prog1</em> exits a non-zero status, +<tt>if</tt> exits 1.</li> + <li> Else <tt>if</tt> execs into <em>prog2</em>. </li> +</ul> + +<h2> Options </h2> + +<ul> + <li> <tt>-X</tt> : treat a crash of <em>prog1</em> as a non-zero ("false") exit. + <li> <tt>-n</tt> : negate the test (exit on true, exec into <em>prog2</em> on false) </li> + <li> <tt>-x</tt> <em>exitcode</em> : exit <em>exitcode</em> instead of 1 if the test fails. </li> + <li> <tt>-t</tt> : exit 0 instead of 1 if the test fails. +This is equivalent to <tt>-x 0</tt>. </li> +</ul> + +<h2> Notes </h2> + +<ul> + <li> <tt>if</tt> will exit if <em>prog1...</em> exits false. To use it in +an execline script that must run <em>prog3...</em> no matter the result of +the test, use a <tt>foreground</tt> wrapper: +<pre> foreground { if { <em>prog1...</em> } <em>prog2...</em> } <em>prog3...</em> </pre> +(in <a href="execlineb.html">execlineb</a> syntax) </li> + <li> <tt>if <em>prog1...</em> "" <em>prog2...</em></tt> is +equivalent to <tt>sh -c '<em>prog1...</em> && exec <em>prog2...</em>'</tt>. </li> +</ul> + +</body> +</html> |