GETENV(3) BSD Library Functions Manual GETENV(3)

NAME
     ggeetteennvv, ppuutteennvv, sseetteennvv, uunnsseetteennvv - environment variable functions

LLIIBBRRAARRYY
     Standard C Library (libc, -lc)

SYNOPSIS
     ##iinncclluuddee <>

     char *
     ggeetteennvv(const char *name);

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

     int
     ppuutteennvv(const char *string);

     void
     uunnsseetteennvv(const char *name);

DESCRIPTION
     These functions set, unset and fetch environment variables from the host
     environment list.  For compatibility with differing environment conven-
     tions, the given arguments name and value may be appended and prepended,
     respectively, with an equal sign ``=''.

     The ggeetteennvv() function obtains the current value of the environment vari-
     able, name.

     The sseetteennvv() 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 ppuutteennvv() function takes an argument of the form ``name=value'' and is
     equivalent to:

           setenv(name, value, 1);

     The uunnsseetteennvv() function deletes all instances of the variable name
     pointed to by name from the list.

RETURN VALUES
     The ggeetteennvv() function returns the value of the environment variable as a
     NUL-terminated string.  If the variable name is not in the current envi-
     ronment, NULL is returned.

     The sseetteennvv() and ppuutteennvv() functions return the value 0 if successful;
     otherwise the value -1 is returned and the global variable errno is set
     to indicate the error.

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

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

STANDARDS     The ggeetteennvv() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

BUGS
     Successive calls to sseetteennvv() or ppuutteennvv() assigning a differently sized
     value to the same name will result in a memory leak.  The FreeBSD seman-
     tics for these functions (namely, that the contents of value are copied
     and that old values remain accessible indefinitely) make this bug
     unavoidable.  Future versions may eliminate one or both of these semantic
     guarantees in order to fix the bug.

HISTORY     The functions sseetteennvv() and uunnsseetteennvv() appeared in Version 7 AT&T UNIX.
     The ppuutteennvv() function appeared in 4.3BSD-Reno.

BSD                            December 11, 1993                           BSD