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 September 18, 2023 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 73.Dv SIGHUP 74is received, for interoperability with 75.Xr newsyslog 1 76and similar log rotation / archival mechanisms. If 77.Fl -output-file 78is not specified, this flag is ignored. 79.It Fl l , Fl -syslog-facility Ar syslog_facility 80These facilities are accepted: 81.Cm auth , authpriv , console , cron , daemon , 82.Cm ftp , kern , lpr , mail , news , ntp , security , 83.Cm syslog , user , uucp , 84and 85local facilities from 86.Cm local0 87to 88.Cm local7 . 89The default is 90.Cm daemon . 91.It Fl m , Fl -output-mask Ar output_mask 92Redirect output from the child process stdout 93.Pq Cm 1 , 94stderr 95.Pq Cm 2 , 96or both 97.Pq Cm 3 . 98This value specifies what is sent to syslog and the log file. 99The default is 100.Cm 3 . 101.It Fl o , Fl -output-file Ar output_file 102Append output from the daemonized process to 103.Pa output_file . 104If the file does not exist, it is created with permissions 0600. 105When this option is used together with options 106.Fl -change-dir 107and 108.Fl -sighup 109the absolute path needs to be provided to ensure 110.Nm 111can re-open the file after a 112.Dv SIGHUP . 113.It Fl P , Fl -supervisor-pidfile Ar supervisor_pidfile 114Write the ID of the 115.Nm 116process into the 117.Ar supervisor_pidfile 118using the 119.Xr pidfile 3 120functionality. 121The program is executed in a spawned child process while the 122.Nm 123waits until it terminates to keep the 124.Ar supervisor_pidfile 125locked and removes it after the process exits. 126The 127.Ar supervisor_pidfile 128owner is the user who runs the 129.Nm 130regardless of whether the 131.Fl -user 132option is used or not. 133.It Fl p , Fl -child-pidfile Ar child_pidfile 134Write the ID of the created process into the 135.Ar child_pidfile 136using the 137.Xr pidfile 3 138functionality. 139The program is executed in a spawned child process while the 140.Nm 141waits until it terminates to keep the 142.Ar child_pidfile 143locked and removes it after the process exits. 144The 145.Ar child_pidfile 146owner is the user who runs the 147.Nm 148regardless of whether the 149.Fl -user 150option is used or not. 151.It Fl R , Fl -restart-delay Ar restart_delay_seconds 152Supervise and restart the program after the specified delay 153if it has been terminated. 154.It Fl r , Fl -restart 155Supervise and restart the program after a one-second delay if it has 156been terminated. 157.It Fl S , Fl -syslog 158Enable syslog output. 159This is implicitly applied if other syslog parameters are provided. 160The default values are daemon, notice, and daemon for facility, priority, and 161tag, respectively. 162.It Fl s , Fl -syslog-priority Ar syslog_priority 163These priorities are accepted: 164.Cm emerg , alert , crit , err , warning , 165.Cm notice , info , 166and 167.Cm debug . 168The default is 169.Cm notice . 170.It Fl T , Fl -syslog-tag Ar syslog_tag 171Set the tag which is appended to all syslog messages. 172The default is 173.Cm daemon . 174.It Fl t , Fl -title Ar title 175Set the title for the daemon process. 176The default is the daemonized invocation. 177.It Fl u , Fl -user Ar user 178Login name of the user to execute the program under. 179Environment variables 180.Ev HOME , USER , 181and 182.Ev SHELL 183are set accordingly. 184Requires adequate superuser privileges. 185.El 186.Pp 187If any of the options 188.Fl -child-pidfile , 189.Fl -output-mask , 190.Fl -restart , 191.Fl -restart-delay , 192.Fl -supervisor-pidfile , 193.Fl -syslog , 194.Fl -syslog-facility 195.Fl -syslog-priority , 196.Fl -syslog-tag , 197or 198.Fl -output , 199are specified, the program is executed in a spawned child process. 200The 201.Nm 202waits until it terminates to keep the pid file(s) locked and removes them 203after the process exits or restarts the program. 204In this case if the monitoring 205.Nm 206receives software termination signal 207.Pq Dv SIGTERM 208it forwards it to the 209spawned process. 210Normally it will cause the child to exit, remove the pidfile(s) 211and then terminate. 212.Pp 213If neither file or syslog output are selected, all output is redirected to the 214.Nm 215process and written to stdout. 216The 217.Fl -close-fds 218option may be used to suppress the stdout output completely. 219.Pp 220The 221.Fl -supervisor-pidfile 222option is useful combined with the 223.Fl -restart 224option as 225.Ar supervisor_pidfile 226contains the ID of the supervisor 227not the child. 228This is especially important if you use 229.Fl -restart 230in an rc script as the 231.Fl -child-pidfile 232option will give you the child's ID to signal when you attempt to 233stop the service, causing 234.Nm 235to restart the child. 236.Sh EXIT STATUS 237The 238.Nm 239utility exits 1 if an error is returned by the 240.Xr daemon 3 241library routine, 2 if 242.Ar child_pidfile 243or 244.Ar supervisor_pidfile 245is requested, but cannot be opened, 3 if process is already running (pidfile 246exists and is locked), 4 if 247.Ar syslog_priority 248is not accepted, 5 if 249.Ar syslog_facility 250is not accepted, 6 if 251.Ar output_mask 252is not within the accepted range, 7 if 253.Ar output_file 254cannot be opened for appending, and otherwise 0. 255.Sh DIAGNOSTICS 256If the command cannot be executed, an error message is printed to 257standard error. 258The exact behavior depends on the logging parameters and the 259.Fl -close-fds 260flag. 261.Sh SEE ALSO 262.Xr nohup 1 , 263.Xr setregid 2 , 264.Xr setreuid 2 , 265.Xr daemon 3 , 266.Xr exec 3 , 267.Xr pidfile 3 , 268.Xr termios 4 , 269.Xr tty 4 270.Sh HISTORY 271The 272.Nm 273utility first appeared in 274.Fx 4.7 . 275