os161 / man / libc / system.html
system.html
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<title>system</title>
<body bgcolor=#ffffff>
<h2 align=center>system</h2>
<h4 align=center>OS/161 Reference Manual</h4>

<h3>Name</h3>
<p>
system - run command as subprocess
</p>

<h3>Library</h3>
<p>
Standard C Library (libc, -lc)
</p>

<h3>Synopsis</h3>
<p>
<tt>#include &lt;stdlib.h&gt;</tt><br>
<br>
<tt>int</tt><br>
<tt>system(const char *</tt><em>command</em><tt>);</tt>
</p>

<h3>Description</h3>
<p>
The <tt>system</tt> routine executes <em>command</em> as if it were
typed into the shell.
</p>

<h3>Return Values</h3>
<p>
On success, system returns the exit status returned from
<A HREF=../syscall/waitpid.html>waitpid</A>.
On error, -1 is returned, and <A HREF=../syscall/errno.html>errno</A>
is set according to the error encountered.
</p>

<h3>Errors</h3>
<p>
Any of the errors from <A HREF=../syscall/fork.html>fork</A> or
<A HREF=../syscall/waitpid.html>waitpid</A>. Errors generated during
<A HREF=../syscall/execv.html>execv</A> cannot readily be reported
back in detail.
</p>

<h3>Restrictions</h3>
<p>
In OS/161 there may be no shell and when there is the shell's behavior
and syntax is not specified. For this reason we make no assumptions
about the shell's operation, and assume <tt>system</tt> cannot
reliably use the shell to parse and execute <em>command</em>.
Instead, <tt>system</tt> does this itself, in a way which may not
necessarily be compatible with the shell as it finally appears. You
may want to change <tt>system</tt> to invoke the shell in a suitable
fashion when/if a shell is available.
</p>

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