KENV(1)                 FreeBSD General Commands Manual                KENV(1)

NAME
     kenv - list or modify the kernel environment

SYNOPSIS
     kenv [-l | -s] [-hNq]
     kenv [-qv] variable[=value]
     kenv [-q] -u variable

DESCRIPTION
     The kenv utility will list all variables in the kernel environment if
     invoked without arguments.

     If the -l option is specified, then the static environment provided by
     loader(8) will be listed instead.  Similarly, the -s option will list the
     static environment defined by the kernel config.  Both of the -l and -s
     options are dependent on the kernel being configured to preserve early
     kernel environments.  The default kernel configuration does not preserve
     these environments.

     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.

EXAMPLES
     Show kernel probe hints variable names and filter for the uart device

           $ kenv -h -N | grep uart
           hint.uart.0.at
           hint.uart.0.flags
           hint.uart.0.irq
           hint.uart.0.port
           hint.uart.1.at
           hint.uart.1.irq
           hint.uart.1.port

     Show the value of a specific variable:

           $ kenv hint.uart.1.at
           isa

     Same as above but adding the name of the variable in the report:

           $ kenv -v hint.uart.1.at
           hint.uart.1.at="isa"

     Try to delete a variable and suppress warnings if any:

           $ kenv -q -u hint.uart.1.at

     Set the value of the verbose_loading variable

           $ kenv verbose_loading="YES"
           verbose_loading="YES"

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

HISTORY
     The kenv utility appeared in FreeBSD 4.1.1.

FreeBSD 13.1-RELEASE-p6          June 20, 2021         FreeBSD 13.1-RELEASE-p6