setenv(3STDC)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | STANDARDS | NOTE | ATTRIBUTES

NAME

getenv, putenv, setenv, unsetenv- fetch and set environment variables

SYNOPSIS

#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 environment list. For compatibility with differing environment conventions, the name and value arguments given may be appended and prepended, respectively, with an equal sign. The getenv function obtains the current value of the environment variable, name. If the variable name is not in the current environment, a null pointer is returned.

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 overwrite argument 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 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.

RETURN VALUES

The setenv and putenv functions return zero if successful; otherwise -1 is returned. The setenv or putenv functions fail if they were unable to allocate memory for the environment.

STANDARDS

The getenv function conforms to ANSI-C .

NOTE

These functions are reentrant, but the environment is global to the actor.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | STANDARDS | NOTE | ATTRIBUTES