Bash Sub Shells

2010-03-02 148 words 1 min read

Taken from <a href="" target="_blank">here.

<span class=\"c\">#!/bin/bash</span>

<span class="nv">server_cmd</span><span class="o">=</span>server <span class="nv">pid_file</span><span class="o">=</span><span class="k">$(</span>basename <span class="nv">$server_cmd</span> .sh<span class="k">)</span>.pid <span class="nv">log_file</span><span class="o">=</span><span class="k">$(</span>basename <span class="nv">$server_cmd</span> .sh<span class="k">)</span>.log

<span class="o">(</span> <span class="nb">echo</span> <span class="s2">"Starting server"</span> <span class="nb">echo</span> <span class="s2">"Doing some init work"</span> <span class="nv">$server_cmd</span> <span class="c"># server becomes a daemon</span>

&lt;span class=\"k\">while &lt;/span>&lt;span class=\"nb\">true&lt;/span>

<span class="nb"> </span><span class="k">do</span> <span class="k"> if</span> <span class="o">[[</span> -f <span class="nv">$pid_file</span> <span class="o">]]</span>; <span class="k">then</span> <span class="k"> </span>sleep 15 <span class="k">else</span> <span class="k"> </span><span class="nb">break</span> <span class="nb"> </span><span class="k">fi</span> <span class="k"> done</span> <span class="k"> </span>mail -s <span class="s2">"Server exitted"</span> <<<CRAP

<span class="o">)</span> 2>&1 >> <span class="nv">$log_file</span> &

<span class="nb">echo</span> <span class="s2">"Server started"</span>

Now this was something which is not new that you can run multiple commands together with &#8221;()&#8221; or that you can run a command in the background with &#8221;&&#8221;, but putting it together in this fashion is really good. I am impressed.

Tags: bash Linux shell


Authored By Amit Agarwal

Amit Agarwal, Linux and Photography are my hobbies.Creative Commons Attribution 4.0 International License.

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