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NAME    [Toc]    [Back]

     getenv, putenv,  setenv,  unsetenv  -  environment  variable

SYNOPSIS    [Toc]    [Back]

     #include <stdlib.h>

     char *
     getenv(const char *name);

     setenv(const char *name, const char *value, int overwrite);

     putenv(const char *string);

     unsetenv(const char *name);

DESCRIPTION    [Toc]    [Back]

     These  functions set, unset, and fetch environment variables
from the host
     environment list.  For compatibility with differing environment conventions,
  the  given  arguments name and value 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  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 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    [Toc]    [Back]

     The functions setenv() and putenv() return zero if  successful; otherwise
     the  global  variable errno is set to indicate the error and
-1 is returned.

     If getenv() is successful, the  string  returned  should  be
considered readonly.

ERRORS    [Toc]    [Back]

     [ENOMEM]   The  function setenv() or putenv() failed because
they were unable
 to allocate memory for the environment.

SEE ALSO    [Toc]    [Back]

     csh(1), sh(1), execve(2), environ(7)

STANDARDS    [Toc]    [Back]

     The getenv() function conforms to ANSI  X3.159-1989  (``ANSI

HISTORY    [Toc]    [Back]

     The  functions setenv() and unsetenv() appeared in Version 7
     The putenv() function appeared in 4.3BSD-Reno.

OpenBSD     3.6                        December     11,      1993
[ Back ]
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