getenv(3c) [opensolaris man page]
getenv(3C) Standard C Library Functions getenv(3C) NAME
getenv - return value for environment name SYNOPSIS
#include <stdlib.h> char *getenv(const char *name); DESCRIPTION
The getenv() function searches the environment list (see environ(5)) for a string of the form name=value and, if the string is present, returns a pointer to the value in the current environment. RETURN VALUES
If successful, getenv() returns a pointer to the value in the current environment; otherwise, it returns a null pointer. USAGE
The getenv() function can be safely called from a multithreaded application. Care must be exercised when using both getenv() and putenv(3C) in a multithreaded application. These functions examine and modify the environment list, which is shared by all threads in an application. The system prevents the list from being accessed simultaneously by two different threads. It does not, however, prevent two threads from successively accessing the environment list using getenv() or putenv(3C). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
exec(2), putenv(3C), attributes(5), environ(5), standards(5) SunOS 5.11 24 Jul 2002 getenv(3C)
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putenv(3C) Standard C Library Functions putenv(3C) NAME
putenv - change or add value to environment SYNOPSIS
#include <stdlib.h> int putenv(char *string); DESCRIPTION
The putenv() function makes the value of the environment variable name equal to value by altering an existing variable or creating a new one. In either case, the string pointed to by string becomes part of the environment, so altering the string will change the environment. The string argument points to a string of the form name=value. The space used by string is no longer used once a new string-defining name is passed to putenv(). The putenv() function uses malloc(3C) to enlarge the environment. putenv() is called, environment variables are not in alphabetical order. RETURN VALUES
Upon successful completion, putenv() returns 0. Otherwise, it returns a non-zero value and sets errno to indicate the error. ERRORS
The putenv() function may fail if: ENOMEM Insufficient memory was available. USAGE
The putenv() function can be safely called from multithreaded programs. Caution must be exercised when using this function and getenv(3C) in multithreaded programs. These functions examine and modify the environment list, which is shared by all threads in a program. The system prevents the list from being accessed simultaneously by two different threads. It does not, however, prevent two threads from successively accessing the environ- ment list using putenv() or getenv(). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
exec(2), getenv(3C), malloc(3C), attributes(5), environ(5), standards(5) WARNINGS
The string argument should not be an automatic variable. It should be declared static if it is declared within a function because it can- not be automatically declared. A potential error is to call putenv() with a pointer to an automatic variable as the argument and to then exit the calling function while string is still part of the environment. SunOS 5.10 7 Aug 2004 putenv(3C)