kenv(1) [freebsd man page]

KENV(1) 						    BSD General Commands Manual 						   KENV(1)

NAME

     kenv -- dump or modify the kernel environment

SYNOPSIS

     kenv [-hNq]
     kenv [-qv] variable[=value]
     kenv [-q] -u variable

DESCRIPTION

     The kenv utility will dump the kernel environment if invoked without arguments.  If the -h option is specified, it will limit the report to
     kernel probe hints.  If an optional variable name is specified, kenv will only report that value.	If the -N option is specified, kenv will
     only display variable names and not their values.	If the -u option is specified, kenv will delete the given environment variable.  If the
     environment variable is followed by an optional value, kenv will set the environment variable to this value.

     If the -q option is set, warnings normally printed as a result of being unable to perform the requested operation will be suppressed.

     If the -v option is set, the variable name will be printed out for the environment variable in addition to the value when kenv is executed
     with a variable name.

     Variables can be added to the kernel environment using the /boot/loader.conf file, or also statically compiled into the kernel using the
     statement

	   env filename

     in the kernel config file.  The file can contain lines of the form

	   name = value # this is a comment

     where whitespace around name and '=', and everything after a '#' character, are ignored.  Almost any printable character except '=' is
     acceptable as part of a name.  Quotes are optional and necessary only if the value contains whitespace.

SEE ALSO

     kenv(2), config(5), loader.conf(5), loader(8)

HISTORY

     The kenv utility appeared in FreeBSD 4.1.1.

BSD
								   May 11, 2012 							       BSD

KENV(2)                                                       BSD System Calls Manual                                                      KENV(2)

NAME

     kenv -- kernel environment

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <kenv.h>

     int
     kenv(int action, const char *name, char *value, int len);

DESCRIPTION

     The kenv() system call manipulates kernel environment variables.  It supports the well known userland actions of getting, setting and unset-
     ting environment variables, as well as the ability to dump all of the entries in the kernel environment.

     The action argument can be one of the following:

     KENV_GET    Returns the value associated with the named kernel environment variable.  If the variable is not found, -1 is returned and the
                 global variable errno is set to ENOENT.  Only the number of bytes available in value are copied out.

     KENV_SET    Sets or adds a new kernel environment variable.  This option is only available to the superuser.

     KENV_UNSET  Unsets the kernel environment variable name.  If the variable does not exist, -1 is returned and the global variable errno is set
                 to EINVAL.  This option is only available to the superuser.

     KENV_DUMP   Dumps as much of the kernel environment as will fit in value.  If value is NULL, kenv() will return the number of bytes required
                 to copy out the entire environment.

     The name argument is the name of the environment variable to be affected.  In the case of KENV_DUMP it is ignored.

     The value argument contains either the value to set the environment variable name to in the case of KENV_SET, or it points to the location
     where kenv() should copy return data to in the case of KENV_DUMP and KENV_GET.  If value is NULL in the case of KENV_DUMP, kenv() will return
     the number of bytes required to copy out the entire environment.

     The len argument indicates how many bytes of storage value points to.

RETURN VALUES

     The kenv() system call returns 0 if successful in the case of KENV_SET and KENV_UNSET, and the number of bytes copied into value in the case
     of KENV_DUMP and KENV_GET.  If an error occurs, a value of -1 is returned and the global variable errno is set to indicate the error.

ERRORS

     The kenv() system call will fail if:

     [EINVAL]           The action argument is not a valid option, or the length of the value is less than 1 for a KENV_SET.

     [ENOENT]           no value could be found for name for a KENV_SET or KENV_UNSET.

     [EPERM]            a user other than the superuser attempted to set or unset a kernel environment variable.

     [EFAULT]           bad address was encountered while attempting to copy in user arguments, or copy out value(s).

     [ENAMETOOLONG]     the name of a variable supplied by the user is longer than KENV_MNAMELEN or the value of a variable is longer than
                        KENV_MVALLEN.

SEE ALSO

     kenv(1)

AUTHORS

     This manual page was written by Chad David <davidc@FreeBSD.org>.

     The kenv() system call was written by Maxime Henrion <mux@FreeBSD.org>.

BSD                                                               April 17, 2002                                                               BSD