.\" 	$NetBSD: rc.subr.8,v 1.31 2012/12/18 13:14:34 wiz Exp $
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.\" by Luke Mewburn.
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.Dd December 17, 2012
.Dt RC.SUBR 8
.Os
.Sh NAME
.Nm rc.subr
.Nd functions used by system shell scripts
.Sh SYNOPSIS
.Bl -item
.It
.Li . /etc/rc.subr
.It
.Ic backup_file Ar action Ar file Ar current Ar backup
.It
.Ic basename Ar file Op Ar suffix
.It
.Ic checkyesno Ar var
.It
.Ic check_pidfile Ar pidfile Ar procname Op Ar interpreter
.It
.Ic check_process Ar procname Op Ar interpreter
.It
.Ic collapse_backslash_newline
.It
.Ic dirname Ar file
.It
.Ic err Ar exitval Ar message
.It
.Ic load_rc_config Ar command
.It
.Ic load_rc_config_var Ar command Ar var
.It
.Ic mount_critical_filesystems Ar type
.It
.Ic no_rc_postprocess Ar command Op Ar arguments
.It
.Ic print_rc_metadata Ar string
.It
.Ic print_rc_normal Oo Fl n Oc Ar string
.It
.Ic rc_usage Ar command Op Ar ...
.It
.Ic reverse_list Ar item Op Ar ...
.It
.Ic run_rc_command Ar argument [parameters]
.It
.Ic run_rc_script Ar file Ar argument
.It
.Ic stop_boot
.It
.Ic twiddle
.It
.Ic wait_for_pids Op Ar pid Op Ar ...
.It
.Ic warn Ar message
.It
.Ic yesno_to_truefalse Ar var
.El
.Sh DESCRIPTION
.Nm
contains commonly used shell script functions which are used by
various scripts such as
.Xr rc 8 ,
and the periodic system services which are controlled by
.Xr daily.conf 5 ,
.Xr monthly.conf 5 ,
.Xr security.conf 5 ,
and
.Xr weekly.conf 5 .
.Pp
The
.Nm
functions are accessed by sourcing
.Pa /etc/rc.subr
into the current shell.
.Pp
The following shell functions are available:
.Bl -tag -width 4n
.It Ic backup_file Ar action Ar file Ar current Ar backup
Make a backup copy of
.Ar file
into
.Ar current .
If the
.Xr rc.conf 5
variable
.Sy backup_uses_rcs
is
.Sq YES ,
use
.Xr rcs 1
to archive the previous version of
.Ar current ,
otherwise save the previous version of
.Ar current
as
.Ar backup .
.Pp
.Ar action
may be one of the following:
.Bl -tag -width remove
.It Sy add
.Ar file
is now being backed up by or possibly re-entered into this backup mechanism.
.Ar current
is created, and if necessary, the
.Xr rcs 1
files are created as well.
.It Sy update
.Ar file
has changed and needs to be backed up.
If
.Ar current
exists, it is copied to
.Ar backup
or checked into
.Xr rcs 1
(if the repository file is old),
and then
.Ar file
is copied to
.Ar current .
.It Sy remove
.Ar file
is no longer being tracked by this backup mechanism.
If
.Xr rcs 1
is being used, an empty file is checked in and
.Ar current
is removed,
otherwise
.Ar current
is moved to
.Ar backup .
.El
.Ic basename Ar file Op Ar suffix
Just like
.Xr basename 1 ,
except implemented using shell built-in commands, and usable before the
.Pa /usr/bin
direcory is available.
.It Ic checkyesno Ar var
Return 0 if
.Ar var
is defined to
.Sq YES ,
.Sq TRUE ,
.Sq ON ,
or
.Sq 1 .
Return 1 if
.Ar var
is defined to
.Sq NO ,
.Sq FALSE ,
.Sq OFF ,
or
.Sq 0 .
Otherwise, warn that
.Ar var
is not set correctly.
The values are case insensitive.
.Pp
Note that the warning message shown by this function when
.Ar var
is not set references a manual page where the user can find more information.
Its name is picked up from the
.Sy rcvar_manpage
variable.
.It Ic check_pidfile Ar pidfile Ar procname Op Ar interpreter
Parses the first word of the first line of
.Ar pidfile
for a PID, and ensures that the process with that PID
is running and its first argument matches
.Ar procname .
Prints the matching PID if successful, otherwise nothing.
If
.Ar interpreter
is provided, parse the first line of
.Ar procname ,
ensure that the line is of the form
.Dl #! interpreter [...]
and use
.Ar interpreter
with its optional arguments and
.Ar procname
appended as the process string to search for.
.It Ic check_process Ar procname Op Ar interpreter
Prints the PIDs of any processes that are running with a first
argument that matches
.Ar procname .
.Ar interpreter
is handled as per
.Ic check_pidfile .
.It Ic collapse_backslash_newline
Copy input to output, collapsing
.Ao backslash Ac Ns Ao newline Ac
to nothing, but leaving other backslashes alone.
.Ic dirname Ar file
Just like
.Xr dirname 1 ,
except implemented using shell built-in commands, and usable before the
.Pa /usr/bin
direcory is available.
.It Ic err Ar exitval Ar message
Display an error message to
.Em stderr ,
log it to the system log
using
.Xr logger 1 ,
and
.Cm exit
with an exit value of
.Ar exitval .
The error message consists of the script name
(from
.Sy $0 ) ,
followed by
.Dq ": ERROR: " ,
and then
.Ar message .
.It Ic load_rc_config Ar command
Source in the
.Xr rc.conf 5
configuration files for
.Ar command .
First,
.Pa /etc/rc.conf
is sourced if it has not yet been read in.
Then,
.Pa /etc/rc.conf.d/ Ns Ar command
is sourced if it is an existing file.
The latter may also contain other variable assignments to override
.Ic run_rc_command
arguments defined by the calling script, to provide an easy
mechanism for an administrator to override the behaviour of a given
.Xr rc.d 8
script without requiring the editing of that script.
.It Ic load_rc_config_var Ar command Ar var
Read the
.Xr rc.conf 5
variable
.Ar var
for
.Ar command
and set in the current shell, using
.Ic load_rc_config
in a sub-shell to prevent unwanted side effects from other variable
assignments.
.It Ic mount_critical_filesystems Ar type
Go through a list of critical file systems,
as found in the
.Xr rc.conf 5
variable
.Sy critical_filesystems_ Ns Ar type ,
mounting each one that
is not currently mounted.
.It Ic no_rc_postprocess Ar command Op Ar arguments
Execute the specified command with the specified arguments,
in such a way that its output bypasses the post-processor that
.Xr rc 8
uses for most commands.
This implies that the output will not appear in the
.Pa /var/run/rc.log
file, and will appear on the console regardless of the
value of
.Va rc_silent .
This is expected to be useful for interactive commands,
and this mechanism is automatically used by
.Ic run_rc_command
when a script contains the
.Xr rcorder 8
keyword
.Dq interactive .
.Pp
If invoked from a context that does not appear to be under the control of
.Xr rc 8 ,
then the command is executed without special treatment.
.It Ic print_rc_metadata Ar string
Print the specified
.Ar string
in such a way that it should be handled as meta-data by the
.Xr rc 8
post-processor.
If invoked from a context that does not appear to be under the control of
.Xr rc 8 ,
then the
.Ar string
is discarded.
.Pp
Any
.Xr rc.d 8
script may invoke this function with an argument that begins with
.Dq note: ,
followed by one line of arbitrary text;
the text will be logged by
.Xr rc 8
but will not be displayed on the console.
.Pp
The use of arguments that do not begin with
.Dq note:
is reserved for internal use by
.Xr rc 8
and
.Nm .
.It Ic print_rc_normal Oo Fl n Oc Ar string
Print the specified
.Ar string
in such a way that it should be handled as normal output by the
.Xr rc 8
post-processor.
If invoked from a context that does not appear to be under the control of
.Xr rc 8 ,
then the
.Ar string
is printed to standard output.
.Pp
If the
.Fl n
flag is specified, then the string is printed without a newline.
.Pp
Intended use cases include:
.Bl -bullet
.It
An rc.d script can use
.Dq Sy print_rc_normal Fl n
to print a partial line in such a way that it appears
immediately instead of being buffered by
.Xr rc 8 Ap s
post-processor.
.It
An rc.d script that is run via the
.Sy no_rc_postprocess
function (so most of its output is invisible to
.Xr rc 8 Ap s
post-processor) can use
.Sy print_rc_normal
to force some of its output to be seen by the post-processor.
.El
.It Ic rc_usage Ar command Op Ar ...
Print a usage message for
.Sy $0 ,
with
.Ar commands
being the list of valid arguments
prefixed by
.Dq "[fast|force|one]" .
.It Ic reverse_list Ar item Op Ar ...
Print the list of
.Ar items
in reverse order.
.It Ic run_rc_command Ar argument Op Ar parameter ...
Run the
.Ar argument
method for the current
.Xr rc.d 8
script, based on the settings of various shell variables.
.Ic run_rc_command
is extremely flexible, and allows fully functional
.Xr rc.d 8
scripts to be implemented in a small amount of shell code.
The optional set of parameters is passed verbatim to the command, but not to its
pre/post hooks.
.Pp
.Ar argument
is searched for in the list of supported commands, which may be one
of:
.Bl -tag -width restart -offset indent
.It Sy start
Start the service.
This should check that the service is to be started as specified by
.Xr rc.conf 5 .
Also checks if the service is already running and refuses to start if
it is.
This latter check is not performed by standard
.Nx
scripts if the system is starting directly to multi-user mode, to
speed up the boot process.
.It Sy stop
If the service is to be started as specified by
.Xr rc.conf 5 ,
stop the service.
This should check that the service is running and complain if it's not.
.It Sy restart
Perform a
.Sy stop
then a
.Sy start .
Defaults to displaying the process ID of the program (if running).
.It Sy rcvar
Display which
.Xr rc.conf 5
variables are used to control the startup of the service (if any).
.El
.Pp
If
.Sy pidfile
or
.Sy procname
is set, also support:
.Bl -tag -width restart -offset indent
.It Sy poll
Wait for the command to exit.
.It Sy status
Show the status of the process.
.El
.Pp
Other supported commands are listed in the optional variable
.Sy extra_commands .
.Pp
.Ar argument
may have one of the following prefixes which alters its operation:
.Bl -tag -width "Prefix" -offset indent
.It Sy fast
Skip the check for an existing running process,
and sets
.Sy rc_fast=YES .
.It Sy force
Skip the checks for
.Sy rcvar
being set to yes,
and sets
.Sy rc_force=YES .
This ignores
.Ar argument Ns Sy _precmd
returning non-zero, and ignores any of the
.Sy required_*
tests failing, and always returns a zero exit status.
.It Sy one
Skip the checks for
.Sy rcvar
being set to yes, but performs all the other prerequisite tests.
.El
.Pp
.Ic run_rc_command
uses the following shell variables to control its behaviour.
Unless otherwise stated, these are optional.
.Bl -tag -width procname -offset indent
.It Sy name
The name of this script.
This is not optional.
.It Sy rcvar
The value of
.Sy rcvar
is checked with
.Ic checkyesno
to determine if this method should be run.
.It Sy rcvar_manpage
The manual page containing information about
.Sy rcvar .
It will be part of the warning message shown when
.Sy rcvar
is undefined.
Defaults to
.Xr rc.conf 5 .
.It Sy command
Full path to the command.
Not required if
.Ar argument Ns Sy _cmd
is defined for each supported keyword.
.It Sy command_args
Optional arguments and/or shell directives for
.Sy command .
.It Sy command_interpreter
.Sy command
is started with
.Dl #! command_interpreter [...]
which results in its
.Xr ps 1
command being
.Dl command_interpreter [...] command
so use that string to find the PID(s) of the running command
rather than
.Ql command .
.It Sy extra_commands
Extra commands/keywords/arguments supported.
.It Sy pidfile
Path to pid file.
Used to determine the PID(s) of the running command.
If
.Sy pidfile
is set, use
.Dl check_pidfile $pidfile $procname
to find the PID.
Otherwise, if
.Sy command
is set, use
.Dl check_process $procname
to find the PID.
.It Sy procname
Process name to check for.
Defaults to the value of
.Sy command .
.It Sy required_dirs
Check for the existence of the listed directories
before running the default start method.
.It Sy required_files
Check for the readability of the listed files
before running the default start method.
.It Sy required_vars
Perform
.Ic checkyesno
on each of the list variables
before running the default start method.
.It Sy ${name}_chdir
Directory to
.Ic cd
to before running
.Sy command ,
if
.Sy ${name}_chroot
is not provided.
.It Sy ${name}_chroot
Directory to
.Xr chroot 8
to before running
.Sy command .
Only supported after
.Pa /usr
is mounted.
.It Sy ${name}_env
List of additional or modified environment variables to set
when starting
.Sy command .
.It Sy ${name}_flags
Arguments to call
.Sy command
with.
This is usually set in
.Xr rc.conf 5 ,
and not in the
.Xr rc.d 8
script.
The environment variable
.Sq Ev flags
can be used to override this.
.It Sy ${name}_nice
.Xr nice 1
level to run
.Sy command
as.
Only supported after
.Pa /usr
is mounted.
.It Sy ${name}_user
User to run
.Sy command
as, using
.Xr chroot 8 .
if
.Sy ${name}_chroot
is set, otherwise
uses
.Xr su 1 .
Only supported after
.Pa /usr
is mounted.
.It Sy ${name}_group
Group to run the chrooted
.Sy command
as.
.It Sy ${name}_groups
Comma separated list of supplementary groups to run the chrooted
.Sy command
with.
.It Ar argument Ns Sy _cmd
Shell commands which override the default method for
.Ar argument .
.It Ar argument Ns Sy _precmd
Shell commands to run just before running
.Ar argument Ns Sy _cmd
or the default method for
.Ar argument .
If this returns a non-zero exit code, the main method is not performed.
If the default method is being executed, this check is performed after
the
.Sy required_*
checks and process (non-)existence checks.
.It Ar argument Ns Sy _postcmd
Shell commands to run if running
.Ar argument Ns Sy _cmd
or the default method for
.Ar argument
returned a zero exit code.
.It Sy sig_stop
Signal to send the processes to stop in the default
.Sy stop
method.
Defaults to
.Dv SIGTERM .
.It Sy sig_reload
Signal to send the processes to reload in the default
.Sy reload
method.
Defaults to
.Dv SIGHUP .
.El
.Pp
For a given method
.Ar argument ,
if
.Ar argument Ns Sy _cmd
is not defined, then a default method is provided by
.Sy run_rc_command :
.Bl -tag -width "argument" -offset indent
.It Sy Argument
.Sy Default method
.It Sy start
If
.Sy command
is not running and
.Ic checkyesno Sy rcvar
succeeds, start
.Sy command .
.It Sy stop
Determine the PIDs of
.Sy command
with
.Ic check_pidfile
or
.Ic check_process
(as appropriate),
.Ic kill Sy sig_stop
those PIDs, and run
.Ic wait_for_pids
on those PIDs.
.It Sy reload
Similar to
.Sy stop ,
except that it uses
.Sy sig_reload
instead, and doesn't run
.Ic wait_for_pids .
.It Sy restart
Runs the
.Sy stop
method, then the
.Sy start
method.
.It Sy status
Show the PID of
.Sy command ,
or some other script specific status operation.
.It Sy poll
Wait for
.Sy command
to exit.
.It Sy rcvar
Display which
.Xr rc.conf 5
variable is used (if any).
This method always works, even if the appropriate
.Xr rc.conf 5
variable is set to
.Sq NO .
.El
.Pp
The following variables are available to the methods
(such as
.Ar argument Ns Sy _cmd )
as well as after
.Ic run_rc_command
has completed:
.Bl -tag -width "rc_flags" -offset indent
.It Sy rc_arg
Argument provided to
.Sy run_rc_command ,
after fast and force processing has been performed.
.It Sy rc_flags
Flags to start the default command with.
Defaults to
.Sy ${name}_flags ,
unless overridden by the environment variable
.Sq Ev flags .
This variable may be changed by the
.Ar argument Ns Sy _precmd
method.
.It Sy rc_pid
PID of
.Sy command
(if appropriate).
.It Sy rc_fast
Not empty if
.Dq fast
prefix was used.
.It Sy rc_force
Not empty if
.Dq force
prefix was used.
.El
.It Ic run_rc_script Ar file Ar argument
Start the script
.Ar file
with an argument of
.Ar argument ,
and handle the return value from the script.
.Pp
Various shell variables are unset before
.Ar file
is started:
.Bd -ragged -offset indent
.Sy name ,
.Sy command ,
.Sy command_args ,
.Sy command_interpreter ,
.Sy extra_commands ,
.Sy pidfile ,
.Sy rcvar ,
.Sy required_dirs ,
.Sy required_files ,
.Sy required_vars ,
.Ar argument Ns Sy _cmd ,
.Ar argument Ns Sy _precmd .
.Ar argument Ns Sy _postcmd .
.Ed
.Pp
The startup behaviour of
.Ar file
depends upon the following checks:
.Bl -enum
.It
If
.Ar file
ends in
.Pa .sh ,
it is sourced into the current shell.
.It
If
.Ar file
appears to be a backup or scratch file
(e.g., with a suffix of
.Sq ~ ,
.Sq # ,
.Sq .OLD ,
or
.Sq .orig ) ,
ignore it.
.It
If
.Ar file
is not executable, ignore it.
.It
If the
.Xr rc.conf 5
variable
.Sy rc_fast_and_loose
is empty,
source
.Ar file
in a sub shell,
otherwise source
.Ar file
into the current shell.
.It
If
.Ar file
contains the
.Xr rcorder 8
keyword
.Dq interactive ,
then the command is executed using
.Ic no_rc_postprocess .
.El
.It Ic stop_boot
Prevent booting to multiuser mode.
If the
.Sy autoboot
variable is
.Sq yes ,
then a
.Sy SIGTERM
signal is sent to the parent
process (which is assumed to be
.Xr rc 8 ) .
Otherwise, the shell exits with status
.Li 1 .
.It Ic twiddle
Display one of the characters
.Sq \&/ , \&- , \&\e , \&| ,
followed by a backspace.
Repeated calls to this function will create the appearance of a spinning
symbol, as a different character is displayed on each call.
Output is to
.Pa /dev/tty ,
so this function may be useful even inside a script whose output
has been redirected.
.It Ic wait_for_pids Op Ar pid Op Ar ...
Wait until all of the provided
.Ar pids
don't exist any more, printing the list of outstanding
.Ar pids
every two seconds.
.It Ic warn Ar message
Display a warning message to
.Em stderr
and log it to the system log
using
.Xr logger 1 .
The warning message consists of the script name
(from
.Sy $0 ) ,
followed by
.Dq ": WARNING: " ,
and then
.Ar message .
.It Ic yesno_to_truefalse Ar var
Change the value of the specified variable from any of the
forms acceptable to the
.Ic checkyesno
function, to
.Dq true
or
.Dq false .
.El
.Sh FILES
.Bl -tag -width /etc/rc.subr -compact
.It Pa /etc/rc.subr
The
.Nm
file resides in
.Pa /etc .
.El
.Sh SEE ALSO
.Xr rc.conf 5 ,
.Xr rc 8
.Sh HISTORY
.Nm
appeared in
.Nx 1.3 .
The
.Xr rc.d 8
support functions appeared in
.Nx 1.5 .
Support for the
.Xr rc 8
post-processor appeared in
.Nx 6.0 .