clearenv(3)

1CLEARENV(3)                Library Functions Manual                CLEARENV(3)
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NAME

6       clearenv - clear the environment
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SYNOPSIS

9       #include <stdlib.h>
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11       int clearenv(void);
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DESCRIPTION

14       The  clearenv() function clears the environment of all name-value pairs
15       and sets the value of the external variable environ to NULL.
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RETURN VALUE

19       The clearenv() function returns zero on success, and a  non-zero  value
20       on failure.
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AVAILABILITY

24       Not in libc4, libc5. In glibc since glibc 2.0.
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CONFORMING TO

28       Various  Unix variants (DG/UX, HP-UX, QNX, ...).  POSIX.9 (bindings for
29       FORTRAN77).  POSIX.1-1996 did not accept clearenv() and  putenv(),  but
30       changed  its mind and scheduled these functions for some later issue of
31       this standard (cf. B.4.6.1).  However, POSIX.1-2001 only adds putenv(),
32       and rejected clearenv().
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NOTES

36       Used  in  security-conscious  applications.  If  it  is unavailable the
37       assignment
38                   environ = NULL;
39       will probably do.
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41       The DG/UX and Tru64 manpages write: If environ  has  been  modified  by
42       anything  other  than  the putenv(), getenv(), or clearenv() functions,
43       then clearenv() will return an error and the process  environment  will
44       remain unchanged.
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