.\" Copyright (c) 2011-2015 Devin Teske
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.\" $FreeBSD$
.\"
.Dd March 4, 2015
.Dt SYSRC 8
.Os
.Sh NAME
.Nm sysrc
.Nd safely edit system rc files
.Sh SYNOPSIS
.Nm
.Op Fl cdDeFhinNqvx
.Op Fl f Ar file
.Op Fl j Ar jail | Fl R Ar dir
.Ar name Ns Op Ns Oo +|- Oc Ns = Ns Ar value
.Ar ...
.Nm
.Op Fl cdDeFhinNqvx
.Op Fl f Ar file
.Op Fl j Ar jail | Fl R Ar dir
.Fl a | A
.Sh DESCRIPTION
The
.Nm
utility retrieves
.Xr rc.conf 5
variables from the collection of system rc files and allows processes with
appropriate privilege to change values in a safe and effective manner.
.Pp
The following options are available:
.Bl -tag -width indent+
.It Fl a
Dump a list of all non-default configuration variables.
.It Fl A
Dump a list of all configuration variables
.Pq incl. defaults .
.It Fl c
Check only.
For querying, return success if all requested variables are set
.Pq even if NULL ,
otherwise return error status.
For assignments, return success if no changes are required, otherwise failure.
If verbose
.Pq see Dq Fl v
prints a message stating whether variables are set and/or changes are required.
.It Fl d
Print a description of the given variable.
.It Fl D
Show default value(s) only (this is the same as setting RC_CONFS to NULL or
passing `-f' with a NULL file-argument).
.It Fl e
Print query results as
.Xr sh 1
compatible syntax
.Pq for example, Ql var=value .
Ignored if either
.Ql Fl n
or
.Ql Fl F
is specified.
.It Fl f Ar file
Operate on the specified file(s) instead of the files obtained by reading the
.Sq rc_conf_files
entry in the
.Ev RC_DEFAULTS
file.
This option can be specified multiple times for additional files.
.It Fl F
Show only the last
.Xr rc.conf 5
file each directive is in.
.It Fl h
Print a short usage message to stderr and exit.
.It Fl -help
Print a full usage statement to stderr and exit.
.It Fl i
Ignore unknown variables.
.It Fl j Ar jail
The
.Ar jid
or name of the
.Ar jail
to operate within
.Pq overrides So Fl R Ar dir Sc ; requires Xr jexec 8 .
.It Fl n
Show only variable values, not their names.
.It Fl N
Show only variable names, not their values.
.It Fl q
Quiet.
Disable verbose and hide certain errors.
.It Fl R Ar dir
Operate within the root directory
.Sq Ar dir
rather than
.Sq / .
.It Fl v
Verbose.
Print the pathname of the specific
.Xr rc.conf 5
file where the directive was found.
.It Fl -version
Print version information to stdout and exit.
.It Fl x
Remove variable(s) from specified file(s).
.El
.Pp
This utility has a similar syntax to
.Xr sysctl 8 .
It shares the `-e' and `-n' options
.Pq detailed above
and also has the same
.Ql name[=value]
syntax for making queries/assignments.
In addition
.Pq but unlike Xr sysctl 8 ,
.Ql name+=value
is supported for adding items to values
.Pq see APPENDING VALUES
and
.Ql name-=value
is supported for removing items from values
.Pq see SUBTRACTING VALUES .
.Pp
However, while
.Xr sysctl 8
serves to query/modify MIBs in the entrant kernel,
.Nm
instead works on values in the system
.Xr rc.conf 5
configuration files.
.Pp
The list of system configuration files is configured in the file
.Ql /etc/defaults/rc.conf
within the variable
.Ql rc_conf_files ,
which by-default contains a space-separated list of pathnames.
On all FreeBSD
systems, this defaults to the value "/etc/rc.conf /etc/rc.conf.local".
Each
pathname is sourced in-order upon startup.
It is in the same fashion that
.Nm
sources the configuration files before returning the value of the given
variable.
.Pp
When supplied a variable name,
.Nm
will return the value of the variable.
If the variable does not appear in any
of the configured
.Ql rc_conf_files ,
an error is printed and error status is returned.
.Pp
When changing values of a given variable, it does not matter if the variable
appears in any of the
.Ql rc_conf_files
or not.
If the variable does not appear in any of the files, it is appended to
the end of the first pathname in the
.Ql rc_conf_files
variable.
Otherwise,
.Nm
will replace only the last-occurrence in the last-file found to contain the
variable.
This gets the value to take effect next boot without heavily
modifying these integral files (yet taking care not to allow the file to
grow unwieldy should
.Nm
be called repeatedly).
.Sh APPENDING VALUES
When using the
.Ql key+=value
syntax to add items to existing values,
the first character of the value is taken as the delimiter separating items
.Pq usually Qo \  Qc or Qo , Qc .
For example, in the following statement:
.Bl -tag -width indent+
.It \ 
.Nm
cloned_interfaces+=" gif0"
.El
.Pp
the first character is a space, informing
.Nm
that existing values are to be considered separated by whitespace.
If
.Ql gif0
is not found in the existing value for
.Va cloned_interfaces ,
it is added
.Pq with delimiter only if existing value is non-NULL .
.Pp
For convenience, if the first character is alpha-numeric
.Pq letters A-Z, a-z, or numbers 0-9 ,
.Nm
uses the default setting of whitespace as separator.
For example, the above and below statements are equivalent since
.Dq gif0
starts with an alpha-numeric character
.Pq the letter Li g :
.Pp
.Bl -tag -width indent+
.It \ 
.Nm
cloned_interfaces+=gif0
.El
.Pp
Take the following sequence for example:
.Bl -tag -width indent+
.It \ 
.Nm
cloned_interfaces= # start with NULL
.It \ 
.Nm
cloned_interfaces+=gif0
.Dl # NULL -> `gif0' Pq NB: no preceding delimiter
.It \ 
.Nm
cloned_interfaces+=gif0 # no change
.It \ 
.Nm
cloned_interfaces+="tun0 gif0"
.Dl # `gif0' -> `gif0 tun0' Pq NB: no duplication
.El
.Pp
.Nm
prevents the same value from being added if already there.
.Sh SUBTRACTING VALUES
When using the
.Ql key-=value
syntax to remove items from existing values,
the first character of the value is taken as the delimiter separating items
.Pq usually Qo \  Qc or Qo , Qc .
For example, in the following statement:
.Pp
.Dl Nm cloned_interfaces-=" gif0"
.Pp
the first character is a space, informing
.Nm
that existing values are to be considered separated by whitespace.
If
.Ql gif0
is found in the existing value for
.Va cloned_interfaces ,
it is removed
.Pq extra delimiters removed .
.Pp
For convenience, if the first character is alpha-numeric
.Pq letters A-Z, a-z, or numbers 0-9 ,
.Nm
uses the default setting of whitespace as separator.
For example, the above and below statements are equivalent since
.Dq gif0
starts with an alpha-numeric character
.Pq the letter Li g :
.Pp
.Bl -tag -width indent+
.It \ 
.Nm
cloned_interfaces-=gif0
.El
.Pp
Take the following sequence for example:
.Bl -tag -width indent+
.It \ 
.Nm
foo="bar baz" # start
.It \ 
.Nm
foo-=bar # `bar baz' -> `baz'
.It \ 
.Nm
foo-=baz # `baz' -> NULL
.El
.Pp
.Nm
removes all occurrences of all items provided
and collapses extra delimiters between items.
.Sh ENVIRONMENT
The following environment variables are referenced by
.Nm :
.Bl -tag -width ".Ev RC_DEFAULTS"
.It Ev RC_CONFS
Override default
.Ql rc_conf_files
.Pq even if set to NULL .
.It Ev RC_DEFAULTS
Location of
.Ql /etc/defaults/rc.conf
file.
.El
.Sh DEPENDENCIES
The following standard commands are required by
.Nm :
.Pp
.Xr awk 1 ,
.Xr cat 1 ,
.Xr chmod 1 ,
.Xr env 1 ,
.Xr grep 1 ,
.Xr jls 1 ,
.Xr mktemp 1 ,
.Xr mv 1 ,
.Xr rm 1 ,
.Xr sh 1 ,
.Xr stat 1 ,
.Xr tail 1 ,
.Xr chown 8
and
.Xr jexec 8 .
.Sh FILES
.Bl -tag -width ".Pa /etc/defaults/rc.conf" -compact
.It Pa /etc/defaults/rc.conf
.It Pa /etc/rc.conf
.It Pa /etc/rc.conf.local
.El
.Sh EXAMPLES
Below are some simple examples of how
.Nm
can be used to query certain values from the
.Xr rc.conf 5
collection of system configuration files:
.Pp
.Nm
sshd_enable
.Dl returns the value of $sshd_enable, usually YES or NO .
.Pp
.Nm
defaultrouter
.Dl returns IP address of default router Pq if configured .
.Pp
Working on other files, such as
.Xr crontab 5 :
.Pp
.Nm
-f /etc/crontab MAILTO
.Dl returns the value of the MAILTO setting Pq if configured .
.Pp
Appending to existing values:
.Pp
.Nm
\&cloned_interfaces+=gif0
.Dl appends Qo gif0 Qc to $cloned_interfaces Pq see APPENDING VALUES .
.Pp
.Nm
\&cloned_interfaces-=gif0
.Dl removes Qo gif0 Qc from $cloned_interfaces Pq see SUBTRACTING VALUES .
.Pp
In addition to the above syntax,
.Nm
also supports inline
.Xr sh 1
PARAMETER expansion for changing the way values are reported, shown below:
.Pp
.Nm
\&'hostname%%.*'
.Dl returns $hostname up to (but not including) first `.' .
.Pp
.Nm
\&'network_interfaces%%[$IFS]*'
.Dl returns first word of $network_interfaces .
.Pp
.Nm
\&'ntpdate_flags##*[$IFS]'
.Dl returns last word of $ntpdate_flags (time server address) .
.Pp
.Nm
usbd_flags-"default"
.Dl returns $usbd_flags or "default" if unset or NULL .
.Pp
.Nm
cloned_interfaces+"alternate"
.Dl returns "alternate" if $cloned_interfaces is set .
.Pp
.Nm
\&'#kern_securelevel'
.Dl returns length in characters of $kern_securelevel .
.Pp
.Nm
\&'hostname?'
.Dl returns NULL and error status 2 if $hostname is unset Pq or if set, returns the value of $hostname with no error status .
.Pp
.Nm
\&'hostname:?'
.Dl returns NULL and error status 2 if $hostname is unset or NULL Pq or if set and non-NULL, returns value without error status .
.Sh LIMITATIONS
The
.Nm
utility presently does not support the
.Ql rc.conf.d
collection of system configuration files
.Pq which requires a service name to be known during execution .
.Pp
This will be corrected by a future enhancement.
.Sh SEE ALSO
.Xr jls 1 ,
.Xr rc.conf 5 ,
.Xr jail 8 ,
.Xr jexec 8 ,
.Xr rc 8 ,
.Xr sysctl 8
.Sh HISTORY
A
.Nm
utility first appeared in
.Fx 9.2 .
.Sh AUTHORS
.An Devin Teske Aq dteske@FreeBSD.org
.Sh THANKS TO
Brandon Gooch, Garrett Cooper, Julian Elischer, Pawel Jakub Dawidek,
Cyrille Lefevre, Ross West, Stefan Esser, Marco Steinbach, Jilles Tjoelker,
Allan Jude, and Lars Engels for suggestions, help, and testing.