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The most common POSIX system calls</TITLE>
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<H1><A NAME="SECTION0010100000000000000000">
8.1 <tt class=module>posix</tt> --
         The most common POSIX system calls</A>
</H1>

<P>
  
<p class=availability>Availability: <span
 class=platform>Unix</span>.</p>

<P>
This module provides access to operating system functionality that is
standardized by the C Standard and the POSIX standard (a thinly
disguised Unix interface).

<P>
<b>Do not import this module directly.</b>  Instead, import the
module <tt class=module><a href="module-os.html">os</a></tt>, which provides a <i>portable</i> version of this
interface.  On Unix, the <tt class=module><a href="module-os.html">os</a></tt> module provides a superset of
the <tt class=module>posix</tt> interface.  On non-Unix operating systems the
<tt class=module>posix</tt> module is not available, but a subset is always
available through the <tt class=module><a href="module-os.html">os</a></tt> interface.  Once <tt class=module><a href="module-os.html">os</a></tt> is
imported, there is <i>no</i> performance penalty in using it instead
of <tt class=module>posix</tt>.  In addition, <tt class=module><a href="module-os.html">os</a></tt><a name="l2h-1439"></a>
provides some additional functionality, such as automatically calling
<tt class=function>putenv()</tt> when an entry in <tt>os.environ</tt> is changed.

<P>
The descriptions below are very terse; refer to the corresponding
Unix manual (or POSIX documentation) entry for more information.
Arguments called <var>path</var> refer to a pathname given as a string.

<P>
Errors are reported as exceptions; the usual exceptions are given for
type errors, while errors reported by the system calls raise
<tt class=exception>error</tt> (a synonym for the standard exception
<tt class=exception>OSError</tt>), described below.

<P>

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