getenv

NAME

<span class="Nm" id="getenv">getenv</span>, <span class="Nm" id="putenv">putenv</span>, <span class="Nm" id="setenv">setenv</span>, <span class="Nm" id="unsetenv">unsetenv</span>

INTERFACE

#include <stdlib.h> char* getenv ( const char *name ) int setenv ( const char *name, const char *value, int overwrite ) int putenv ( const char *string ) void unsetenv ( const char *name )

DESCRIPTION

These functions set, unset and fetch environment variables from the host <span class="Em">environment</span> <span class="Em">list</span>. For compatibility with differing environment conventions, the given arguments name and value may be appended and prepended, respectively, with an equal sign "<span class="Dq"><span class="Li">=</span>.</span>"

The getenv function obtains the current value of the environment variable, name.

The setenv function inserts or resets the environment variable name in the current environment list. If the variable name does not exist in the list, it is inserted with the given value. If the variable does exist, the argument overwrite is tested; if overwrite is zero, the variable is not reset, otherwise it is reset to the given value.

The putenv function takes an argument of the form ``name=value&#039;&#039; and is equivalent to:

setenv(name, value, 1);

The unsetenv function deletes all instances of the variable name pointed to by name from the list.