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PUTENV(3)                  Library Functions Manual                  PUTENV(3)



NAME
       putenv - change or add value to environment

SYNOPSIS
       int putenv(string)
       char *string;

DESCRIPTION
       string  points  to a string of the form `name=value' putenv() 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 space used by string is no
       longer used once a new string-defining name is passed to putenv().

SEE ALSO
       execve(2V), getenv(3V), malloc(3V), environ(5V).

DIAGNOSTICS
       putenv() returns non-zero if it was unable to obtain enough space using
       malloc(3V) for an expanded environment, otherwise zero.

WARNINGS
       putenv()  manipulates the environment pointed to by environ, and can be
       used in conjunction with getenv().  However, envp (the  third  argument
       to main) is not changed.

       This routine uses malloc(3V) to enlarge the environment.

       After putenv() is called, environmental variables are not in alphabeti-
       cal order.

       A potential error is to call putenv() with an automatic variable as the
       argument,  then exit the calling function while string is still part of
       the environment.



                               21 February 1989                      PUTENV(3)