<!-- Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009, 2013 The President and Fellows of Harvard College. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. --> <html> <head> <title>getenv</title> <body bgcolor=#ffffff> <h2 align=center>getenv</h2> <h4 align=center>OS/161 Reference Manual</h4> <h3>Name</h3> <p> getenv - retrieve an environment variable </p> <h3>Library</h3> <p> Standard C Library (libc, -lc) </p> <h3>Synopsis</h3> <p> <tt>#include <stdlib.h></tt><br> <br> <tt>char *</tt><br> <tt>getenv(const char *</tt><em>variable</em><tt>);</tt> </p> <h3>Description</h3> <p> <tt>getenv</tt> retrieves the value of the environment variable <em>variable</em> from the current process environment. Unless you implement <tt>execve</tt> and environment variable passing, the environment used is a default environment compiled into libc. </p> <h3>Return Values</h3> <p> On success, <tt>getenv</tt> returns a pointer to the value of the requested variable. This pointer points to internal storage and the contents should not be modified. The contents will in turn be stable until/unless the process environment is modified. If the requested variable is not found, <tt>getenv</tt> returns <tt>NULL</tt>. </p> <h3>See Also</h3> <p> <A HREF=execvp.html>execvp</A> </p> </body> </html>