1.\" Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved. 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 3. Berkeley Software Design Inc's name may not be used to endorse or 12.\" promote products derived from this software without specific prior 13.\" written permission. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd January 14, 2021 30.Dt DAEMON 8 31.Os 32.Sh NAME 33.Nm daemon 34.Nd run detached from the controlling terminal 35.Sh SYNOPSIS 36.Nm 37.Op Fl cfHrS 38.Op Fl p Ar child_pidfile 39.Op Fl P Ar supervisor_pidfile 40.Op Fl t Ar title 41.Op Fl u Ar user 42.Op Fl m Ar output_mask 43.Op Fl o Ar output_file 44.Op Fl s Ar syslog_priority 45.Op Fl T Ar syslog_tag 46.Op Fl l Ar syslog_facility 47.Op Fl R Ar restart_delay_seconds 48.Ar command arguments ... 49.Sh DESCRIPTION 50The 51.Nm 52utility detaches itself from the controlling terminal and 53executes the program specified by its arguments. 54Privileges may be lowered to the specified user. 55The output of the daemonized process may be redirected to syslog and to a 56log file. 57.Pp 58The options are as follows: 59.Bl -tag -width indent 60.It Fl c 61Change the current working directory to the root 62.Pq Dq Pa / . 63.It Fl f 64Redirect standard input, standard output and standard error to 65.Pa /dev/null . 66When this option is used together with any of the options related to file 67or syslog output, the standard file descriptors are first redirected to 68.Pa /dev/null , 69then stdout and/or stderr is redirected to a file or to syslog as 70specified by the other options. 71.It Fl H 72Close 73.Pa output_file 74and re-open it when signal SIGHUP is received, for interoperability with 75.Xr newsyslog 1 76and similar log rotation / archival mechanisms. If 77.Fl o 78is not specified, this flag is ignored. 79.It Fl S 80Enable syslog output. 81This is implicitly applied if other syslog parameters are provided. 82The default values are daemon, notice, and daemon for facility, priority, and 83tag, respectively. 84.It Fl o Ar output_file 85Append output from the daemonized process to 86.Pa output_file . 87If the file does not exist, it is created with permissions 0600. 88When this option is used together with options 89.Fl c 90and 91.Fl H 92the absolute path needs to be provided to ensure 93.Nm 94can re-open the file after a SIGHUP. 95.It Fl m Ar output_mask 96Redirect output from the child process stdout (1), stderr (2), or both (3). 97This value specifies what is sent to syslog and the log file. 98The default is 3. 99.It Fl p Ar child_pidfile 100Write the ID of the created process into the 101.Ar child_pidfile 102using the 103.Xr pidfile 3 104functionality. 105The program is executed in a spawned child process while the 106.Nm 107waits until it terminates to keep the 108.Ar child_pidfile 109locked and removes it after the process exits. 110The 111.Ar child_pidfile 112owner is the user who runs the 113.Nm 114regardless of whether the 115.Fl u 116option is used or not. 117.It Fl P Ar supervisor_pidfile 118Write the ID of the 119.Nm 120process into the 121.Ar supervisor_pidfile 122using the 123.Xr pidfile 3 124functionality. 125The program is executed in a spawned child process while the 126.Nm 127waits until it terminates to keep the 128.Ar supervisor_pidfile 129locked and removes it after the process exits. 130The 131.Ar supervisor_pidfile 132owner is the user who runs the 133.Nm 134regardless of whether the 135.Fl u 136option is used or not. 137.It Fl r 138Supervise and restart the program after a one-second delay if it has 139been terminated. 140.It Fl R Ar restart_delay_seconds 141Supervise and restart the program after the specified delay 142if it has been terminated. 143.It Fl t Ar title 144Set the title for the daemon process. 145The default is the daemonized invocation. 146.It Fl u Ar user 147Login name of the user to execute the program under. 148Requires adequate superuser privileges. 149.It Fl s Ar syslog_priority 150These priorities are accepted: emerg, alert, crit, err, warning, 151notice, info, and debug. 152The default is notice. 153.It Fl l Ar syslog_facility 154These facilities are accepted: auth, authpriv, console, cron, daemon, 155ftp, kern, lpr, mail, news, ntp, security, syslog, user, uucp, and 156local0, ..., local7. 157The default is daemon. 158.It Fl T Ar syslog_tag 159Set the tag which is appended to all syslog messages. 160The default is daemon. 161.El 162.Pp 163If any of the options 164.Fl p , 165.Fl P , 166.Fl r , 167.Fl o , 168.Fl s , 169.Fl T , 170.Fl m , 171.Fl S , 172or 173.Fl l 174are specified, the program is executed in a spawned child process. 175The 176.Nm 177waits until it terminates to keep the pid file(s) locked and removes them 178after the process exits or restarts the program. 179In this case if the monitoring 180.Nm 181receives software termination signal (SIGTERM) it forwards it to the 182spawned process. 183Normally it will cause the child to exit, remove the pidfile(s) 184and then terminate. 185.Pp 186If neither file or syslog output are selected, all output is redirected to the 187.Nm 188process and written to stdout. 189The 190.Fl f 191option may be used to suppress the stdout output completely. 192.Pp 193The 194.Fl P 195option is useful combined with the 196.Fl r 197option as 198.Ar supervisor_pidfile 199contains the ID of the supervisor 200not the child. 201This is especially important if you use 202.Fl r 203in an rc script as the 204.Fl p 205option will give you the child's ID to signal when you attempt to 206stop the service, causing 207.Nm 208to restart the child. 209.Sh EXIT STATUS 210The 211.Nm 212utility exits 1 if an error is returned by the 213.Xr daemon 3 214library routine, 2 if 215.Ar child_pidfile 216or 217.Ar supervisor_pidfile 218is requested, but cannot be opened, 3 if process is already running (pidfile 219exists and is locked), 4 if 220.Ar syslog_priority 221is not accepted, 5 if 222.Ar syslog_facility 223is not accepted, 6 if 224.Ar output_mask 225is not within the accepted range, 7 if 226.Ar output_file 227cannot be opened for appending, and otherwise 0. 228.Sh DIAGNOSTICS 229If the command cannot be executed, an error message is printed to 230standard error. 231The exact behavior depends on the logging parameters and the 232.Fl f 233flag. 234.Sh SEE ALSO 235.Xr nohup 1 , 236.Xr setregid 2 , 237.Xr setreuid 2 , 238.Xr daemon 3 , 239.Xr exec 3 , 240.Xr pidfile 3 , 241.Xr termios 4 , 242.Xr tty 4 243.Sh HISTORY 244The 245.Nm 246utility first appeared in 247.Fx 4.7 . 248