Provided by: daemon_0.8.4-1_amd64 
NAME
daemon - turns other processes into daemons
SYNOPSIS
usage: daemon [options] [--] [cmd arg...]
options:
-h, --help - Print a help message then exit
-V, --version - Print a version message then exit
-v, --verbose[=level] - Set the verbosity level
-d, --debug[=level] - Set the debugging level
-C, --config=path - Specify the system configuration file
-N, --noconfig - Bypass the system configuration file
-n, --name=name - Guarantee a single named instance
-X, --command="cmd" - Specify the client command as an option
-P, --pidfiles=/dir - Override standard pidfile location
-F, --pidfile=/path - Override standard pidfile name and location
-u, --user=user[:[group]] - Run the client as user[:group]
-R, --chroot=path - Run the client with path as root
-D, --chdir=path - Run the client in directory path
-m, --umask=umask - Run the client with the given umask
-e, --env="var=val" - Set a client environment variable
-i, --inherit - Inherit environment variables
-U, --unsafe - Allow execution of unsafe executable
-S, --safe - Disallow execution of unsafe executable
-c, --core - Allow core file generation
--nocore - Disallow core file generation (default)
-r, --respawn - Respawn the client when it terminates
-a, --acceptable=# - Minimum acceptable client duration (seconds)
-A, --attempts=# - Respawn # times on error before delay
-L, --delay=# - Delay between respawn attempt bursts (seconds)
-M, --limit=# - Maximum number of respawn attempt bursts
--idiot - Idiot mode (trust root with the above)
-f, --foreground - Run the client in the foreground
-p, --pty[=noecho] - Allocate a pseudo terminal for the client
-B, --bind - Stop when the user's last logind session ends
-l, --errlog=spec - Send daemon's error output to syslog or file
-b, --dbglog=spec - Send daemon's debug output to syslog or file
-o, --output=spec - Send client's output to syslog or file
-O, --stdout=spec - Send client's stdout to syslog or file
-E, --stderr=spec - Send client's stderr to syslog or file
--ignore-eof - After SIGCHLD ignore any client output
--read-eof - After SIGCHLD read any client output (default)
--running - Check if a named daemon is running
--restart - Restart a named daemon client
--stop - Terminate a named daemon process
--signal=signame - Send a signal to a named daemon
--list - Print a list of named daemons
DESCRIPTION
daemon(1) turns other processes into daemons. There are many tasks that need to be
performed to correctly set up a daemon process. This can be tedious. daemon performs these
tasks for other processes.
The preparatory tasks that daemon performs for other processes are:
• First, revoke any setuid or setgid privileges that daemon may have been installed with
(by system administrators who laugh in the face of danger).
• Process command line options.
• Change the root directory if the --chroot option was supplied.
• Change the process uid and gid if the --user option was supplied. Only root can use
this option. Note that the uid of daemon itself is changed, rather than just changing
the uid of the client process.
• Read the system configuration file(s) (/etc/daemon.conf and /etc/daemon.conf.d/* by
default, or specified by the --config option), unless the --noconfig option was
supplied. Then read the user's personal configuration file(s) (~/.daemonrc and
~/.daemonrc.d/*), if any. Generic options that apply to all daemons are processed
first, then options that are specific to the daemon with the given name. Note: The
root directory and the user must be set before access to the configuration file(s) can
be attempted, so neither the --chroot nor --user options may appear in the
configuration file.
On BSD systems (except macOS), the system configuration file(s) are
/usr/local/etc/daemon.conf and /usr/local/etc/daemon.conf.d/* by default.
On macOS, when installed via macports, the system configuration file(s) are
/opt/local/etc/daemon.conf and /opt/local/etc/daemon.conf.d/*.
• Disable core file generation to prevent leaking potentially sensitive information in
daemons that are run by root (unless the --core option was supplied).
• Become a daemon process:
• If daemon was not invoked by init(8) (i.e. parent process id 1) or inetd(8) (i.e.
stdin is a socket):
• Ignore SIGHUP signals in case the current process session leader terminates
while attached to a controlling terminal, causing us to receive a SIGHUP
signal before we start our own process session below.
This can happen when daemon was invoked interactively via the shell builtin
exec. When this initial process terminates below, the terminal emulator that
invoked the shell also terminates, so daemon need to protect itself from that.
• Background the process to lose process group leadership.
• Start a new process session.
• Background the process again to lose process session leadership. Under SVR4,
this prevents the process from ever gaining a controlling terminal. This is
only necessary under SVR4, but is always done for simplicity. Note that
ignoring SIGHUP signals earlier means that when the newly created process
session leader terminates, then even if it has a controlling terminal open,
the newly backgrounded process won't receive the corresponding SIGHUP signal
that is sent to all processes in the process session's foreground process
group, because it inherited signal dispositions from the initial process.
• Change the current directory to the root directory so as not to hamper umounts.
• Clear the umask to enable explicit file creation modes.
• Close all open file descriptors. If daemon was invoked by inetd(8), stdin, stdout
and stderr are left open, because they are open to a socket.
• Open stdin, stdout and stderr to /dev/null, in case something requires them to be
open. Of course, this is not done if daemon was invoked by inetd(8).
• If the --name option was supplied, create and lock a file containing the process
id of the daemon process. The presence of this locked file prevents two instances
of a daemon with the same name from running at the same time. The default location
of the pidfile is /var/run for root (/etc on Solaris, /opt/local/var/run on macOS
when installed via macports), and /tmp for normal users. If the --pidfiles option
was supplied, its argument specifies the directory in which the pidfile will be
placed. If the --pidfile option was supplied, its argument specifies the name of
the pidfile and the directory in which it will be placed.
• If the --umask option was supplied, set the umask to its argument, which must be a
valid three-digit octal mode. Otherwise, set the umask to 022, to prevent clients from
accidentally creating group- or world-writable files.
• Set the current directory if the --chdir option was supplied.
• Spawn the client command and wait for it to terminate. The client command can be
specified as command line arguments, or as the argument of the --command option. If
both the --command option and command line arguments are present, the client command
is the result of appending the command line arguments to the argument of the --command
option.
• If the --output, --stdout and/or --stderr options were supplied, the client's standard
output and/or standard error are captured by daemon, and are sent to the respective
syslog destinations.
• When the client terminates, daemon respawns it if the --respawn option was supplied.
If the client ran for less than 300 seconds (or the value of the --acceptable option),
then daemon sees this as a failure. It will attempt to restart the client up to five
times (or the value of the --attempts option), before waiting for 300 seconds (or the
value of the --delay option). This gives the system administrator the chance to
correct whatever is preventing the client from running successfully without
overloading system resources. If the --limit option was supplied, daemon terminates
after the specified number of respawn attempt bursts. The default is zero, which
means never give up, never surrender.
When the client terminates, and the --respawn option wasn't supplied, daemon
terminates as well.
• If daemon receives a SIGTERM signal (e.g. from a separate invocation of daemon with
the --stop option), it propagates the signal to the client and then terminates.
• If daemon receives a SIGUSR1 signal (from a separate invocation of daemon with the
--restart option), it sends a SIGTERM signal to the client. If it was started with the
--respawn option, the client process will be restarted after it is terminated by the
SIGTERM signal.
• If the --foreground option was supplied, the client process is run as a foreground
process, and is not turned into a daemon at all. If daemon is connected to a terminal,
then the client process will also be connected to it. If daemon is not connected to a
terminal, but the client needs to be connected to a terminal, use the --pty option.
OPTIONS
-h, --help
Display a help message and exit.
-V, --version
Display a version message and exit.
-v[level], --verbose[=level]
Set the message verbosity level to level (or 1 if level is not supplied). This only
effects the --running and --list options.
-d[level], --debug[=level]
Set the debug message level to level (or 1 if level is not supplied). Level 1 traces
high-level function calls. Level 2 traces lower-level function calls and shows
configuration information. Level 3 adds environment variables. Level 9 adds every
return value from select(2). Debug messages are sent to the destination specified by
the --dbglog option (by default, the syslog(3) facility, daemon.debug).
-C path, --config=path
Specify the system configuration file to use. By default, /etc/daemon.conf is the
system configuration file, if it exists and is not group- or world-writable, and does
not exist in a group- or world-writable directory. The configuration file lets you
predefine options that apply to all clients, and to specifically named clients.
As well as the system configuration file, additional configuration files will be read
from the directory whose path matches the system configuration file with ".d" appended
to it (e.g. /etc/daemon.conf.d). Any file in that directory whose name starts with a
dot character (".") is ignored. The same checks as described above apply to these
files as well.
On BSD systems (except macOS), the system configuration file(s) are
/usr/local/etc/daemon.conf and /usr/local/etc/daemon.conf.d/* by default.
On macOS, when installed via macports, the system configuration file(s) are
/opt/local/etc/daemon.conf and /opt/local/etc/daemon.conf.d/*.
-N, --noconfig
Bypass the system configuration files, /etc/daemon.conf and /etc/daemon.conf.d/*. Only
the user's ~/.daemonrc and ~/.daemonrc.d/* configuration files will be read (if they
exist).
-n name, --name=name
Create and lock a pidfile (name.pid), ensuring that only one daemon with the given
name is active at the same time. The standard location of the pidfile is /var/run for
root (/etc on Solaris, /opt/local/var/run on macOS when installed via macports), and
/tmp for normal users. This location can be overridden with the --pidfiles option.
The name may only consist of the following characters:
-._abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
While a named daemon's client process is running, there will also be a separate
pidfile to record the process id of the client process. Its filename will be the same
as the daemon pidfile's, except that the filename extension will be .clientpid rather
than .pid. The only reason that there should be a .pid file, with no .clientpid file,
is during the delay between respawn attempts bursts.
-X "cmd", --command="cmd"
Specify the client command as an option. If a command is specified along with its name
in the configuration file, then a daemon can be invoked merely by mentioning its name:
daemon --name ftumch
Note: If the client command is specified with the --command option, either in the
configuration file, or on the command line, then any additional command line arguments
on the daemon command line are appended to the client command that is specified with
the --command option.
-P /dir, --pidfiles=/dir
Override the standard pidfile location. The standard pidfile location is /var/run for
root (/etc on Solaris, /opt/local/var/run on macOS when installed via macports), and
/tmp for normal users.
This option only affects the --name and --list options. Use this option if these
standard locations are unacceptable, but make sure that you don't forget where you put
your pidfiles. This option is best used in configuration files, or in shell scripts,
rather than on an interactive command line.
The pidfile location will be created automatically only if it is within the user's
home directory.
-F /path, --pidfile=/path
Override the standard pidfile name and location. The standard pidfile location is
described immediately above. The standard pidfile name is the argument of the --name
option followed by .pid. Use this option if the standard pidfile name and location are
unacceptable, but make sure that you don't forget where you put your pidfile. This
option is best used in configuration files, or in shell scripts, rather than on an
interactive command line.
The pidfile location will be created automatically only if it is within the user's
home directory.
-u user[:[group]], --user=user[:[group]]
Run the client as a different user (and group). This only works for root. If the
argument includes a :group specifier, daemon will assume the specified group and no
other. Otherwise, daemon will assume all groups that the specified user is in. For
backwards compatibility, "." may be used instead of ":" to separate the user and group
but since "." can appear in user and group names, ambiguities can arise such as using
--user=u.g when users u and u.g and group g all exist. With such an ambiguity, daemon
will assume the user u and group g. Use --user=u.g: instead for the other
interpretation.
-R path, --chroot=path
Change the root directory to path before running the client. On some systems, only
root can do this. Note that the path to the client program and to the configuration
file (if any) must be relative to the new root path.
-D path, --chdir=path
Change the current directory to path before running the client. The default current
directory is the root directory (possibly after chroot).
-m umask, --umask=umask
Change the umask to umask before running the client. umask must be a valid octal mode.
The default umask is 022.
-e "var=val", --env="var=val"
Set an environment variable for the client process. This option can be used any number
of times. If it is used, only the supplied environment variables are passed to the
client process. Otherwise, the client process inherits the current set of environment
variables.
-i, --inherit
Explicitly inherit environment variables. This is only needed when the --env option is
used. When this option is used, the --env option adds to the inherited environment,
rather than replacing it.
-U, --unsafe
Allow reading an unsafe configuration file, and allow the execution of an unsafe
executable. A configuration file or executable is considered to be unsafe if it is
group- or world-writable or is in a directory that is group- or world-writable
(following symbolic links). If an executable is a script that is interpreted by
another executable, then it is considered to be unsafe if the interpreter is unsafe.
If the interpreter is /usr/bin/env (with an argument that is a command name to be
searched for in $PATH), then that command must be safe. By default, daemon(1) will
refuse to read an unsafe configuration file or to execute an unsafe executable when
run by root. This option overrides that behaviour and hence should never be used.
-S, --safe
Disallow reading an unsafe configuration file, and disallow the execution of an unsafe
executable. By default, daemon(1) will allow reading an unsafe configuration file, and
allow the execution of an unsafe executable, when run by normal users. This option
overrides that behaviour.
-c, --core
Allow the client to create a core file. This should only be used for debugging, as it
could lead to security-related information disclosures by daemons run by root.
--nocore
By default, clients are prevented from creating a core file. If the --core option has
been used in a configuration file to apply to all named daemons, then this option can
be used to restore the default behaviour for specific named daemons.
-r, --respawn
Respawn the client when it terminates. Without this option, the termination of a
client process causes daemon itself to terminate as well.
-a #, --acceptable=#
Specify the minimum acceptable duration of a client process, in seconds. This option
can only be used with the --respawn option. If a client process terminates before this
threshold is reached, then it is considered to have failed. The default value is 300
seconds. It cannot be set to less than 10 seconds, except by root when used in
conjunction with the --idiot option.
-A #, --attempts=#
Specify the number of attempts to respawn before delaying. This option can only be
used with the --respawn option. The default value is 5. It cannot be set to more than
100 attempts, except by root when used in conjunction with the --idiot option.
-L #, --delay=#
Specify the delay in seconds between each burst of respawn attempts. This option can
only be used with the --respawn option. The default value is 300 seconds. It cannot be
set to less than 10 seconds except by root when used in conjunction with the --idiot
option.
-M #, --limit=#
Specify a limit to the number of respawn attempt bursts. This option can only be used
with the --respawn option. The default value is 0, which means no limit.
--idiot
Turn on idiot mode in which daemon will not enforce the minimum or maximum values
normally imposed on the --acceptable, --attempts and --delay options. The --idiot
option must appear before any of these options. Only the root user may use this
option, because it can turn a slight misconfiguration into a lot of wasted CPU energy
and log messages, somewhat akin to a self-inflicted denial of service.
Idiot mode also allows the root user to expand environment variable notation (e.g.
$VAR and ${VAR}) in command line option arguments, and in configuration files. By
default, internal environment variable expansion is only performed for normal users.
Note that this doesn't apply to any such expansion performed earlier by the shell that
invokes daemon(1). See the EXPANSION section below for more details.
-f, --foreground
Run the client in the foreground. The client is not turned into a daemon.
-p[noecho], --pty[=noecho]
Connect the client to a pseudo terminal. This option can only be used with the
--foreground option. This is the default when the --foreground option is supplied and
daemon's standard input is connected to a terminal. This option is only necessary when
the client process must be connected to a controlling terminal, but daemon itself has
been run without a controlling terminal (e.g. from cron(8) or a pipeline).
If the noecho argument is supplied with this option, the client's side of the pseudo
terminal will be set to noecho mode. Use this only if there really is a terminal
involved and input is being echoed twice.
-B, --bind
Automatically terminate the client process (and daemon(1) itself) as soon as the user
has no systemd-logind(8) (or elogind(8)) user sessions. In other words, automatically
terminate when the user logs out. If the user has no sessions to start with, the
client process will be terminated immediately.
This option is only available on Linux systems that have either systemd(1) (e.g.
Debian) or elogind(8) (e.g. Slackware). On systems with systemd(1), you could instead
use a systemd user service, particularly if your user account is not allowed to have
user services that linger.
-l spec, --errlog=spec
Send daemon's standard output and standard error to the syslog destination or file
that is specified by spec. If spec is a syslog destination of the form
"facility.priority", then output is sent to syslog(3). Otherwise, output is appended
to the file whose path is given in spec. By default, output is sent to the syslog
destination, daemon.err. See the MESSAGING section below for more details.
-b spec, --dbglog=spec
Send daemon's debug output to the syslog destination or file that is specified by
spec. If spec is a syslog destination of the form "facility.priority", then output is
sent to syslog(3). Otherwise, output is appended to the file whose path is given in
spec. By default, output is sent to the syslog destination daemon.debug. See the
MESSAGING section below for more details.
-o spec, --output=spec
Capture the client's standard output and standard error, and send it to the syslog
destination or file that is specified by spec. If spec is a syslog destination of the
form "facility.priority", then output is sent to syslog(3). Otherwise, output is
appended to the file whose path is given in spec. By default, output is discarded
unless the --foreground option is present, in which case, the client's stdout and
stderr are propagated to daemon's stdout and stderr, respectively. See the MESSAGING
section below for more details.
-O spec, --stdout=spec
Capture the client's standard output, and send it to the syslog destination or file
that is specified by spec. If spec is a syslog destination of the form
"facility.priority", then output is sent to syslog(3). Otherwise, stdout is appended
to the file whose path is given in spec. By default, stdout is discarded unless the
--foreground option is present, in which case, the client's stdout is propagated to
daemon's stdout. See the MESSAGING section below for more details.
-E spec, --stderr=spec
Capture the client's standard error, and send it to the syslog destination or file
that is specified by spec. If spec is a syslog destination of the form
"facility.priority", then stderr is sent to syslog(3). Otherwise, stderr is appended
to the file whose path is given in spec. By default, stderr is discarded unless the
--foreground option is present, in which case, the client's stderr is propagated to
daemon's stderr. See the MESSAGING section below for more details.
--ignore-eof
After receiving a SIGCHLD signal due to a stopped or restarted client process, don't
bother reading the client's output until the end-of-file is reached before reaping the
client process's termination status with wait(2). Normally, there will be little or no
output after the SIGCHLD signal, because the client process has just terminated.
However, the client process might have its own child processes keeping its output open
long after its own termination. When this happens, by default, the client process
remains as a zombie process until its child processes terminate and close the output.
Waiting for the client's child processes to terminate before considering the client
stopped, and before restarting a new invocation, might be desirable. If not, this
option can be used to consider the client process as being terminated as soon as the
SIGCHLD signal has been received, and reaping its termination status with wait(2)
immediately.
--read-eof
After receiving a SIGCHLD signal due to a stopped or restarted client process,
continue reading the client's output until the end-of-file is reached before reaping
the client process's termination status with wait(2). This is the default behaviour.
Normally, there will be little or no output after the SIGCHLD signal, because the
client process has just terminated. However, the client process might have its own
child processes keeping its output open long after its own termination. When this
happens, the client process remains as a zombie process until its child processes
terminate and close the output. Waiting for the client's child processes to terminate
before considering the client stopped, and before restarting a new invocation, might
be desirable. If so, but the --ignore-eof option has been used in a configuration file
to apply to all named daemons, then this option can be used to restore the default
behaviour for specific named daemons.
--running
Check whether or not a named daemon is running, then exit(3) with EXIT_SUCCESS if the
named daemon is running or EXIT_FAILURE if it isn't.
If the --verbose option is supplied, print a message before exiting. If both the named
daemon and its client process are running, the output will look like this, showing
both process IDs:
daemon: name is running (pid 7455) (clientpid 7457)
If the named daemon is running but its client process is not (there might be a delay
between respawn attempt bursts), the output will look like this, showing only the
daemon process's ID:
daemon: name is running (pid 7455) (client is not running)
If the named daemon is not running at all, the output will look like this:
daemon: name is not running
This option can only be used with the --name option. Note that the --chroot, --user,
--name, --pidfiles and --pidfile (and possibly --config) options must be the same as
for the target daemon.
--restart
Instruct a named daemon to terminate and restart its client process, by sending it a
SIGUSR1 signal. This will cause the named daemon to send its client process a SIGTERM
signal to stop it. If the named daemon had been started with the --restart option, the
named daemon will then restart its client process. Otherwise, this has the same effect
as the --stop option, and the named daemon's client process is not restarted.
This option can only be used with the --name option. Note that the --chroot, --user,
--name, --pidfiles and --pidfile (and possibly --config) options must be the same as
for the target daemon.
--stop
Stop a named daemon by sending it a SIGTERM signal. This will cause the named daemon
to send its client process a SIGTERM option and then exit.
This option can only be used with the --name option. Note that the --chroot, --user,
--name, --pidfiles and --pidfile (and possibly --config) options must be the same as
for the target daemon.
--signal=signame
Send the given signal to a named daemon's client process. The signal can be specified
either by number or by name (with or without the "sig" prefix). Any signal may be
sent. However, the named daemon's client process might be ignoring some signals. For
example, SIGHUP will be ignored by default unless the client process has installed a
signal handler for it.
The known list of signals are: hup, int, quit, ill, trap, abrt, iot, bus, fpe, kill,
usr1, segv, usr2, pipe, alrm, term, stkflt, cld, chld, cont, stop, tstp, ttin, ttou,
urg, xcpu, xfsz, vtalrm, prof, winch, poll, io, pwr, sys, emt and info. Not all of
them are available on all platforms.
--list
Print a list of the currently running named daemons whose pidfiles are in the
applicable pidfile directory which will either be the default (i.e. /var/run for root
(/etc on Solaris, /opt/local/var/run on macOS when installed via macports), and /tmp
for normal users), or it will be specified by the --pidfiles option. Then exit.
Without the --verbose option, this will only list the names of daemons whose pidfiles
are locked, as this implies that the corresponding daemon must still be running. Note
that pidfiles for daemons that were not started by daemon(1) might not be locked. An
unlocked pidfile might indicate that daemon(1) has died unexpectedly, or it might just
be a pidfile for a daemon that was not started by daemon(1). If this might lead to
confusion, you might want to consider using a dedicated pidfiles directory for named
daemons started by daemon(1), and leave the default pidfiles directories for other
daemons that were started independently of daemon(1).
With the --verbose option, the items in the list will look like the output of the
--running option with --verbose, but with more detail.
If there are no pidfiles at all, the output will look like this:
No named daemons are running
If a pidfile is locked, and there is a corresponding client pidfile, that indicates
that the named daemon and its client are both running, and the output will look like
this, showing both process IDs:
name is running (pid ####) (client pid ####)
If a pidfile is locked, but there is no client pidfile, that indicates that the named
daemon is running, but its client is not (e.g. during a delay between respawn attempt
bursts when the client is failing to start successfully), and the output will look
like one of the following three options:
When we can tell that the pidfile is for a process whose executable name is daemon:
name is running (pid ####) (client is not running)
When we can tell that the pidfile is for a process whose executable name is something
other than daemon (i.e. is independent of daemon(1)):
name is running (pid ####) (independent)
When it's not possible to determine the name of the executable associated with the
pidfile (i.e. On systems other than Linux without a /proc file system):
name is running (pid ####) (client is not running or is independent)
If a pidfile is not locked, and the applicable pidfiles directory is the default, that
indicates either that the daemon has unexpectedly terminated, or just that the pidfile
is for a daemon that was not started by daemon(1), and the output will look like this:
name is not running (or is independent)
If a pidfile is not locked, and the applicable pidfiles directory is not the default,
then it is assumed that all pidfiles are for daemons that were started by daemon(1),
and the output will look like this:
name is not running
As with all other programs, a -- argument signifies the end of options. Any options that
appear on the command line after -- are part of the client command.
EXPANSION
Some simple shell-like expansion is performed internally on the arguments of the command
line options with a text argument (but not the options with a numeric argument).
Environment variable notation, such as $VAR or ${VAR}, is expanded. Then user home
directory notation, such as ~ or ~user, is expanded. File name expansion (i.e. globbing)
is NOT performed internally. Neither are any of your login shell's other wonderful
expansions. This is very basic.
This might not be of much use on the command line, since daemon is normally invoked via a
shell, which will first perform all of its usual expansions. It might even be undesirable
to perform expansion internally after the shell has already done so (e.g. if you refer to
any directory names that actually contain the '$' character, or if you use any environment
variables whose values contain the '$' character, which is unlikely).
But it can be useful in configuration files. See the FILES section below for more details.
It can also be useful when daemon is invoked directly by another program without the use
of a shell.
By default, environment variable expansion is not performed for the root user, even if the
environment variable was defined in the configuration files. The --idiot option can be
used to change this behaviour, and allow the expansion of environment variables for the
root user. Home directory notation expansion is performed for all users.
FILES
/etc/daemon.conf, /etc/daemon.conf.d/* - system-wide default options
/usr/local/etc/daemon.conf, /usr/local/etc/daemon.conf.d/* - system-wide default options
on BSD systems (except macOS).
/opt/local/etc/daemon.conf, /opt/local/etc/daemon.conf.d/* - system-wide default options
on macOS when installed via macports.
~/.daemonrc, ~/.daemonrc.d/* - user-specific default options
Each line of the configuration file is either an environment variable definition, or a
configuration directive.
Environment variable definitions consist of the variable name, followed immediately by '='
and the value of the variable. They look like they do in shell, except that there is no
quoting or other shell syntax. Environment variable values can include simple environment
variable notation (e.g. $VAR or ${VAR}), and user home directory notation (e.g. ~ or
~user). These will be expanded internally by daemon. See the EXPANSION section above for
more details.
Note that any environment variables that are defined in the configuration file, which are
subsequently used explicitly in another environment variable definition or in an option
argument, will have these expansions performed multiple times. Avoid environment variables
whose values can change again if expansion is performed multiple times.
Example:
PATH=/usr/bin:/usr/sbin:$HOME/bin:~app/bin
PIDFILES=~/.run
Configuration directives consist of a client name (for options that apply to a single
client), or '*' (for generic options that apply to all clients), followed by spaces and/or
tabs, followed by a comma-separated list of options. Any option arguments must not contain
any commas. The commas that separate options can have spaces and tabs before and after
them. Option arguments that are text (but not numbers) can include simple environment
variable notation (e.g. $VAR or ${VAR}), and user home directory notation (e.g. ~ or
~user). These will be expanded internally by daemon. See the EXPANSION section above for
more details.
Blank lines and comments ('#' to end of the line) are ignored. Lines can be continued with
a '\' character at the end of the line.
Example:
* errlog=daemon.err,output=local0.err,core
test1 syslog=local0.debug,debug=9,verbose=9,respawn
test2 syslog=local0.debug,debug=9, \
verbose=9,respawn, \
pidfiles=$PIDFILES
The command line options are processed first, to look for a --config option. If no
--config option was supplied, the default configuration files, /etc/daemon.conf and
/etc/daemon.conf.d/*, are used. On BSD systems (except macOS), the default configuration
files are /usr/local/etc/daemon.conf and /usr/local/etc/daemon.conf.d/*. On macOS when
installed via macports, the default configuration files are /opt/local/etc/daemon.conf and
/opt/local/etc/daemon.conf.d/*. If the user has their own configuration files,
~/.daemonrc and ~/.daemonrc.d/*, they are also used.
If the configuration files contain any generic ('*') entries, their options are applied in
order of appearance. If the --name option was supplied, and the configuration files
contain any entries for the given name, those options are then applied in order of
appearance.
Finally, the command line options are applied again. This ensures that any generic options
apply to all clients by default. Client-specific options override generic options. User
options override system-wide options. Command line options override everything else.
Note that the configuration files are not opened and read until after any --chroot and/or
--user command line options are processed. This means that the configuration file paths
and the client's file path must be relative to the --chroot argument. It also means that
the configuration files and the client executable must be readable/executable by the user
specified by the --user argument. It also means that the --chroot and --user options must
not appear in the configuration file. Also note that the --name option must not appear on
the right hand side in the configuration file either.
MESSAGING
The --errlog, --dbglog, --output, --stdout and --stderr options all take an argument that
can be either a syslog destination of the form "facility.priority" or the path to a file.
Here are the lists of syslog facilities and priorities:
Facilities:
kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron,
local0, local1, local2, local3, local4, local5, local6, local7.
Priorities:
emerg, alert, crit, err, warning, notice (on some systems), info, debug.
If the path to a file is supplied instead, bear in mind the fact that daemon(1) changes to
the root directory by default, and so the file path should be an absolute path (or
relative to the --chroot and/or --chdir option argument). Otherwise, daemon(1) will
attempt to create the file relative to its current directory. You might not have
permissions to do that, or want to even if you do.
CAVEAT
Clients can only be restarted if they were started with the --respawn option. Using
--restart on a non-respawning daemon client is equivalent to using --stop. If you try to
restart a named daemon, and it stops instead, then it probably wasn't started with the
--respawn option.
Clients that are run in the foreground with a pseudo terminal don't respond to job control
(i.e. suspending with Control-Z doesn't work). This is because the client belongs to an
orphaned process group (it starts in its own process session), so the kernel won't send it
SIGSTOP signals. However, if the client is a shell that supports job control, then its
subprocesses can be suspended.
In KDE, if you use "exec daemon" (or just "exec" without daemon) in a shell, to run a KDE
application, you might find that the KDE application sometimes doesn't run. This problem
has only been seen with konsole(1), but it might happen with other KDE applications as
well. Capturing the standard error of the KDE application might show something like:
unnamed app(9697): KUniqueApplication: Registering failed!
unnamed app(9697): Communication problem with "konsole" , it probably crashed.
Error message was: "org.freedesktop.DBus.Error.ServiceUnknown" : " "The name
org.kde.konsole was not provided by any .service files"
A workaround seems to be to delay the termination of the initial daemon(1) process by at
least 0.4 seconds. To make this happen, set the environment variable
DAEMON_INIT_EXIT_DELAY_MSEC to the number of milliseconds by which to delay. For example:
DAEMON_INIT_EXIT_DELAY_MSEC=400. Or you could just avoid using exec when starting KDE
applications.
On Linux systems that have systemd(1) or elogind(8), you might find that your daemon
processes and their client processes are terminated when you logout, even though they are
in a different process session, and so should be unaffected. This is because systemd has
the ability to terminate all of your processes when you logout. Luckily, this feature is
turned off by default in some Linux distributions. However, if it is on, you can turn it
off by adding the following line to /etc/systemd/logind.conf (or
/etc/elogind/logind.conf):
KillUserProcesses=no
SEE ALSO
libslack(3), daemon(3), coproc(3), pseudo(3), init(8), inetd(8), fork(2), umask(2),
setsid(2), chdir(2), chroot(2), setrlimit(2), setgid(2), setuid(2), setgroups(2),
initgroups(3), syslog(3), kill(2), wait(2), systemd-logind(8), elogind(8)
AUTHOR
20230824 raf <raf@raf.org>