SYSRC(8)

NAME
sysrc - safely edit system rc files

SYNOPSIS
sysrc [-cdDeFhinNqvx] [-f file] [-j jail | -R dir] name[=value] ...
sysrc [-cdDeFhinNqvx] [-f file] [-j jail | -R dir] -a | -A

DESCRIPTION
The sysrc utility retrieves 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.

The following options are available:

-a  Dump a list of all non-default configuration variables.

-A  Dump a list of all configuration variables (incl. defaults).

-c  Check if the value will change when assigning a new value. If verbose (see “-v”) prints a message stating whether a change would occur. Exits with success if no change is necessary, else returns error status.

-d  Print a description of the given variable.

-D  Show default value(s) only (this is the same as setting RC_CONFS to NULL or passing `-f' with a NULL file-argument).

-e  Print query results as sh(1) compatible syntax (for example, ‘var=value’). Ignored if either ‘-n’ or ‘-F’ is specified.

-f file
    Operate on the specified file(s) instead of the files obtained by reading the ‘rc_conf_files’ entry in the RC_DEFAULTS file. This option can be specified multiple times for additional files.

-F  Show only the last rc.conf(5) file each directive is in.

-h  Print a short usage message to stderr and exit.

--help
    Print a full usage statement to stderr and exit.

-i  Ignore unknown variables.

-j jail
    The jid or name of the jail to operate within (overrides ‘-R dir’; requires jexec(8)).

-n  Show only variable values, not their names.

-N  Show only variable names, not their values.

-q  Quiet. Ignore previous occurrences of -v flag.

-R dir
    Operate within the root directory (‘dir’) rather than (‘/’).

-v  Verbose. Print the pathname of the specific rc.conf(5) file where the directive was found.

--version
    Print version information to stdout and exit.

-x  Remove variable(s) from specified file(s).

This utility works similar to sysctl(8). It shares the `-e' and `-n' options (detailed above) and also has the same ‘name[=value]’ syntax for querying/setting configuration options.

However, while sysctl(8) serves to query/modify MIBs in the entrant kernel, sysrc instead works on values in the system rc.conf(5) configuration files.

The list of system configuration files is configured in the file ‘/etc/defaults/rc.conf’ within the variable ‘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 sysrc sources the configuration files before returning the value of the given variable.

When supplied a variable name, sysrc will return the value of the variable. If the variable does not appear in any of the configured ‘rc_conf_files’, an error is printed and error status is returned.

When changing values of a given variable, it does not matter if the variable appears in any of the ‘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 ‘rc_conf_files’ variable. Otherwise, sysrc 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 sysrc be called repeatedly).

ENVIRONMENT
The following environment variables are referenced by sysrc:

RC_CONFS
    Override default ‘rc_conf_files’ (even if set to NULL).

RC_DEFAULTS
    Location of ‘/etc/defaults/rc.conf’ file.

DEPENDENCIES
The following standard commands are required by sysrc:

awk(1), cat(1), chmod(1), env(1), grep(1), jls(1), mktemp(1), mv(1), rm(1), sh(1), stat(1), tail(1), chown(8) and jexec(8).

FILES
/etc/defaults/rc.conf
/etc/rc.conf
/etc/rc.conf.local

EXAMPLES
Below are some simple examples of how sysrc can be used to query certain values from the rc.conf(5) collection of system configuration files:

sysrc sshd_enable
    returns the value of $sshd_enable, usually YES or NO.

sysrc defaultrouter
    returns IP address of default router (if configured).

Working on other files, such as crontab(5):

sysrc -f /etc/crontab MAILTO
    returns the value of the MAILTO setting (if configured).

In addition to the above syntax, sysrc also supports inline sh(1) PARAMETER expansion for changing the way values are reported, shown below:

sysrc 'hostname%%.*'
    returns $hostname up to (but not including) first `.'.

sysrc 'network_interfaces%%[$IFS]*'
    returns first word of $network_interfaces.

sysrc 'ntpdate_flags##*[$IFS]'
    returns last word of $ntpdate_flags (time server address).

sysrc usbd_flags-"default"
    returns $usbd_flags or default if unset or NULL.

sysrc cloned_interfaces+"alternate"
    returns alternate if $cloned_interfaces is set.

sysrc '#kern_securelevel'
    returns length in characters of $kern_securelevel.

sysrc 'hostname?'
    returns NULL and error status 2 if $hostname is unset (or if set, returns the value of $hostname with no error status).

sysrc 'hostname:?'
    returns NULL and error status 2 if $hostname is unset or NULL (or if set and non-NULL, returns value without error status).

LIMITATIONS
The sysrc utility presently does not support the ‘rc.conf.d’ collection of system configuration files (which requires a service name to be known during execution).

This will be corrected by a future enhancement.

SEE ALSO
jls(1), rc.conf(5), jail(8), jexec(8), rc(8), sysctl(8)

HISTORY
A sysrc utility first appeared in FreeBSD 9.2.

AUTHORS
Devin Teske <dteske@FreeBSD.org>

THANKS TO
Brandon Gooch, Garrett Cooper, Julian Elischer, Pawel Jakub Dawidek, Cyrille Lefevre, Ross West, Stefan Esser, Marco Steinbach, and Jilles Tjoelker for suggestions and help.