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.Dd January 14, 2021 28.Dt DAEMON 8 29.Os 30.Sh NAME 31.Nm daemon 32.Nd run detached from the controlling terminal 33.Sh SYNOPSIS 34.Nm 35.Op Fl cfHrS 36.Op Fl p Ar child_pidfile 37.Op Fl P Ar supervisor_pidfile 38.Op Fl t Ar title 39.Op Fl u Ar user 40.Op Fl m Ar output_mask 41.Op Fl o Ar output_file 42.Op Fl s Ar syslog_priority 43.Op Fl T Ar syslog_tag 44.Op Fl l Ar syslog_facility 45.Op Fl R Ar restart_delay_seconds 46.Ar command arguments ... 47.Sh DESCRIPTION 48The 49.Nm 50utility detaches itself from the controlling terminal and 51executes the program specified by its arguments. 52Privileges may be lowered to the specified user. 53The output of the daemonized process may be redirected to syslog and to a 54log file. 55.Pp 56The options are as follows: 57.Bl -tag -width indent 58.It Fl c , Fl -change-dir 59Change the current working directory to the root 60.Pq Dq Pa / . 61.It Fl f , Fl -close-fds 62Redirect standard input, standard output and standard error to 63.Pa /dev/null . 64When this option is used together with any of the options related to file 65or syslog output, the standard file descriptors are first redirected to 66.Pa /dev/null , 67then stdout and/or stderr is redirected to a file or to syslog as 68specified by the other options. 69.It Fl H , Fl -sighup 70Close 71.Pa output_file 72and re-open it when signal SIGHUP is received, for interoperability with 73.Xr newsyslog 1 74and similar log rotation / archival mechanisms. If 75.Fl -output-file 76is not specified, this flag is ignored. 77.It Fl S , Fl -syslog 78Enable syslog output. 79This is implicitly applied if other syslog parameters are provided. 80The default values are daemon, notice, and daemon for facility, priority, and 81tag, respectively. 82.It Fl o , Fl -output-file Ar output_file 83Append output from the daemonized process to 84.Pa output_file . 85If the file does not exist, it is created with permissions 0600. 86When this option is used together with options 87.Fl -change-dir 88and 89.Fl -sighup 90the absolute path needs to be provided to ensure 91.Nm 92can re-open the file after a SIGHUP. 93.It Fl m , Fl -output-mask Ar output_mask 94Redirect output from the child process stdout (1), stderr (2), or both (3). 95This value specifies what is sent to syslog and the log file. 96The default is 3. 97.It Fl p , Fl -child-pidfile Ar child_pidfile 98Write the ID of the created process into the 99.Ar child_pidfile 100using the 101.Xr pidfile 3 102functionality. 103The program is executed in a spawned child process while the 104.Nm 105waits until it terminates to keep the 106.Ar child_pidfile 107locked and removes it after the process exits. 108The 109.Ar child_pidfile 110owner is the user who runs the 111.Nm 112regardless of whether the 113.Fl -user 114option is used or not. 115.It Fl P , Fl -supervisor-pidfile Ar supervisor_pidfile 116Write the ID of the 117.Nm 118process into the 119.Ar supervisor_pidfile 120using the 121.Xr pidfile 3 122functionality. 123The program is executed in a spawned child process while the 124.Nm 125waits until it terminates to keep the 126.Ar supervisor_pidfile 127locked and removes it after the process exits. 128The 129.Ar supervisor_pidfile 130owner is the user who runs the 131.Nm 132regardless of whether the 133.Fl -user 134option is used or not. 135.It Fl r , Fl -restart 136Supervise and restart the program after a one-second delay if it has 137been terminated. 138.It Fl R , Fl -restart-delay Ar restart_delay_seconds 139Supervise and restart the program after the specified delay 140if it has been terminated. 141.It Fl t , Fl -title Ar title 142Set the title for the daemon process. 143The default is the daemonized invocation. 144.It Fl u , Fl -user Ar user 145Login name of the user to execute the program under. 146Requires adequate superuser privileges. 147.It Fl s , Fl -syslog-priority Ar syslog_priority 148These priorities are accepted: emerg, alert, crit, err, warning, 149notice, info, and debug. 150The default is notice. 151.It Fl l , Fl -syslog-facility Ar syslog_facility 152These facilities are accepted: auth, authpriv, console, cron, daemon, 153ftp, kern, lpr, mail, news, ntp, security, syslog, user, uucp, and 154local0, ..., local7. 155The default is daemon. 156.It Fl T , Fl -syslog-tag Ar syslog_tag 157Set the tag which is appended to all syslog messages. 158The default is daemon. 159.El 160.Pp 161If any of the options 162.Fl -child-pidfile , 163.Fl -output-mask , 164.Fl -restart , 165.Fl -restart-delay , 166.Fl -supervisor-pidfile , 167.Fl -syslog , 168.Fl -syslog-facility 169.Fl -syslog-priority , 170.Fl -syslog-tag , 171or 172.Fl -output , 173are specified, the program is executed in a spawned child process. 174The 175.Nm 176waits until it terminates to keep the pid file(s) locked and removes them 177after the process exits or restarts the program. 178In this case if the monitoring 179.Nm 180receives software termination signal (SIGTERM) it forwards it to the 181spawned process. 182Normally it will cause the child to exit, remove the pidfile(s) 183and then terminate. 184.Pp 185If neither file or syslog output are selected, all output is redirected to the 186.Nm 187process and written to stdout. 188The 189.Fl -close-fds 190option may be used to suppress the stdout output completely. 191.Pp 192The 193.Fl -supervisor-pidfile 194option is useful combined with the 195.Fl -restart 196option as 197.Ar supervisor_pidfile 198contains the ID of the supervisor 199not the child. 200This is especially important if you use 201.Fl -restart 202in an rc script as the 203.Fl -child-pidfile 204option will give you the child's ID to signal when you attempt to 205stop the service, causing 206.Nm 207to restart the child. 208.Sh EXIT STATUS 209The 210.Nm 211utility exits 1 if an error is returned by the 212.Xr daemon 3 213library routine, 2 if 214.Ar child_pidfile 215or 216.Ar supervisor_pidfile 217is requested, but cannot be opened, 3 if process is already running (pidfile 218exists and is locked), 4 if 219.Ar syslog_priority 220is not accepted, 5 if 221.Ar syslog_facility 222is not accepted, 6 if 223.Ar output_mask 224is not within the accepted range, 7 if 225.Ar output_file 226cannot be opened for appending, and otherwise 0. 227.Sh DIAGNOSTICS 228If the command cannot be executed, an error message is printed to 229standard error. 230The exact behavior depends on the logging parameters and the 231.Fl -close-fds 232flag. 233.Sh SEE ALSO 234.Xr nohup 1 , 235.Xr setregid 2 , 236.Xr setreuid 2 , 237.Xr daemon 3 , 238.Xr exec 3 , 239.Xr pidfile 3 , 240.Xr termios 4 , 241.Xr tty 4 242.Sh HISTORY 243The 244.Nm 245utility first appeared in 246.Fx 4.7 . 247