putenv(3C)           COMPATIBILITY FUNCTIONS           putenv(3C)



NAME
     putenv - change or add value to environment

SYNOPSIS
     #include <stdlib.h>

     int putenv (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.   Because  of  this  limitation,  string  should  be
     declared static if it is declared within a function.

SEE ALSO
     exec(2), getenv(3C), malloc(3C), environ(5).

DIAGNOSTICS
     putenv returns non-zero if it was unable  to  obtain  enough
     space  via  malloc  for  an  expanded environment, otherwise
     zero.

NOTES
     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(3C) to enlarge the environment.
     After putenv is called, environmental variables are  not  in
     alphabetical  order.  A potential error is to call the func-
     tion 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.


















          Last change: C Programming Language Utilities         1