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1 | package MooseX::Daemonize::Core; |
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2 | use strict; # cause Perl::Critic errors are annoying |
3 | use MooseX::Getopt; # to load the NoGetopt metaclass |
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4 | use Moose::Role; |
5 | |
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6 | use POSIX (); |
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7 | |
8 | has is_daemon => ( |
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9 | # NOTE: |
10 | # this should never be accessible |
11 | # from the command line |
12 | # - SL |
13 | metaclass => 'NoGetopt', |
14 | isa => 'Bool', |
15 | is => 'rw', |
16 | default => sub { 0 }, |
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17 | ); |
18 | |
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19 | has ignore_zombies => ( |
20 | metaclass => 'Getopt', |
21 | isa => 'Bool', |
22 | is => 'rw', |
23 | default => sub { 0 }, |
24 | ); |
25 | |
26 | has no_double_fork => ( |
27 | metaclass => 'Getopt', |
28 | isa => 'Bool', |
29 | is => 'rw', |
30 | default => sub { 0 }, |
31 | ); |
32 | |
33 | has dont_close_all_files => ( |
34 | metaclass => 'Getopt', |
35 | isa => 'Bool', |
36 | is => 'rw', |
37 | default => sub { 0 }, |
38 | ); |
39 | |
40 | sub _get_options { |
41 | my ($self, %options) = @_; |
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42 | # backwards compatibility.. old code might be calling daemon_fork/_detach with options |
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43 | foreach my $opt (qw( ignore_zombies no_double_fork dont_close_all_files )) { |
44 | $self->$opt( $options{ $opt } ) if ( defined $options{ $opt } ); |
45 | } |
46 | } |
47 | |
48 | |
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49 | sub daemon_fork { |
50 | my ($self, %options) = @_; |
51 | |
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52 | $self->_get_options( %options ); |
53 | |
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54 | $SIG{CHLD} = 'IGNORE' |
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55 | if $self->ignore_zombies;; |
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56 | |
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57 | if (my $pid = fork) { |
58 | return $pid; |
59 | } |
60 | else { |
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61 | $self->is_daemon(1); |
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62 | return; |
63 | } |
64 | } |
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65 | |
66 | sub daemon_detach { |
67 | my ($self, %options) = @_; |
68 | |
69 | return unless $self->is_daemon; # return if parent ... |
70 | |
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71 | $self->_get_options( %options ); |
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72 | # now we are in the daemon ... |
73 | |
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74 | (POSIX::setsid) # set session id |
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75 | || confess "Cannot detach from controlling process"; |
76 | |
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77 | unless ( $self->no_double_fork ) { |
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78 | $SIG{'HUP'} = 'IGNORE'; |
79 | fork && exit; |
80 | } |
81 | |
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82 | chdir '/'; # change to root directory |
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83 | umask 0; # clear the file creation mask |
84 | |
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85 | unless ( $self->dont_close_all_files ) { |
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86 | # get the max number of possible file descriptors |
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87 | my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX ); |
88 | $openmax = 64 if !defined($openmax) || $openmax < 0; |
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89 | |
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90 | # close them all |
91 | POSIX::close($_) foreach (0 .. $openmax); |
92 | } |
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93 | |
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94 | # fixup STDIN ... |
95 | |
96 | open(STDIN, "+>/dev/null") |
97 | or confess "Could not redirect STDOUT to /dev/null"; |
98 | |
99 | # fixup STDOUT ... |
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100 | |
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101 | if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) { |
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102 | open STDOUT, ">", $stdout_file |
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103 | or confess "Could not redirect STDOUT to $stdout_file : $!"; |
104 | } |
105 | else { |
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106 | open(STDOUT, "+>&STDIN") |
107 | or confess "Could not redirect STDOUT to /dev/null"; |
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108 | } |
109 | |
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110 | # fixup STDERR ... |
111 | |
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112 | if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) { |
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113 | open STDERR, ">", $stderr_file |
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114 | or confess "Could not redirect STDERR to $stderr_file : $!"; |
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115 | } |
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116 | else { |
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117 | open(STDERR, "+>&STDIN") |
118 | or confess "Could not redirect STDERR to /dev/null"; ; |
119 | } |
120 | |
121 | # do a little house cleaning ... |
122 | |
123 | # Avoid 'stdin reopened for output' |
124 | # warning with newer perls |
125 | open( NULL, '/dev/null' ); |
126 | <NULL> if (0); |
127 | |
128 | # return success |
129 | return 1; |
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130 | } |
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131 | |
132 | sub daemonize { |
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133 | my ($self, %options) = @_; |
134 | $self->daemon_fork(%options); |
135 | $self->daemon_detach(%options); |
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136 | } |
137 | |
138 | 1; |
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139 | |
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140 | __END__ |
141 | |
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142 | =pod |
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143 | |
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144 | =head1 NAME |
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145 | |
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146 | MooseX::Daemonize::Core - A Role with the core daemonization features |
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147 | |
148 | =head1 SYNOPSIS |
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149 | |
150 | package My::Daemon; |
151 | use Moose; |
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152 | |
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153 | with 'MooseX::Daemonize::Core'; |
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154 | |
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155 | sub start { |
156 | my $self = shift; |
157 | # daemonize me ... |
158 | $self->daemonize; |
159 | # return from the parent,... |
160 | return unless $self->is_daemon; |
161 | # but continue on in the child (daemon) |
162 | } |
163 | |
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164 | =head1 DESCRIPTION |
165 | |
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166 | This is the basic daemonization Role, it provides a few methods (see |
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167 | below) and the minimum features needed to properly daemonize your code. |
168 | |
169 | =head2 Important Notes |
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170 | |
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171 | None of the methods in this role will exit the parent process for you, |
172 | it only forks and detaches your child (daemon) process. It is your |
173 | responsibility to exit the parent process in some way. |
174 | |
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175 | There is no PID or PID file management in this role, that is your |
176 | responsibility (see some of the other roles in this distro for that). |
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177 | |
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178 | =head1 ATTRIBUTES |
179 | |
180 | =over |
181 | |
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182 | =item I<is_daemon (is => rw, isa => Bool)> |
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183 | |
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184 | This attribute is used to signal if we are within the |
185 | daemon process or not. |
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186 | |
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187 | =item I<no_double_fork (is => rw, isa => Bool)> |
188 | |
189 | Setting this attribute to true will cause this method to not perform the |
190 | typical double-fork, which is extra added protection from your process |
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191 | accidentally acquiring a controlling terminal. More information can be |
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192 | found above, and by Googling "double fork daemonize". |
193 | |
194 | If you the double-fork behavior off, you might want to enable the |
195 | I<ignore_zombies>. |
196 | |
197 | =item I<ignore_zombies (is => rw, isa => Bool)> |
198 | |
199 | Setting this attribute to a true value will result in setting the C<$SIG{CHLD}> |
200 | handler to C<IGNORE>. This tells perl to clean up zombie processes. By |
201 | default, and for the most part you don't I<need> it, only when you turn off |
202 | the double fork behavior (with the I<no_double_fork> attribute) |
203 | do you sometimes want this behavior. |
204 | |
205 | =item I<dont_close_all_files (is => rw, isa => Bool)> |
206 | |
207 | Setting this attribute to true will cause it to skip closing all the |
208 | filehandles. This is useful if you are opening things like sockets |
209 | and such in the pre-fork. |
210 | |
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211 | =back |
212 | |
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213 | =head1 METHODS |
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214 | |
215 | =over |
216 | |
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217 | =item B<daemon_fork (?%options)> |
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218 | |
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219 | This forks off the child process to be daemonized. Just as with |
220 | the built in fork, it returns the child pid to the parent process, |
221 | 0 to the child process. It will also set the is_daemon flag |
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222 | appropriately. |
223 | |
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224 | The C<%options> argument remains for backwards compatibility, but |
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225 | it is suggested that you use the attributes listed above instead. |
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226 | |
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227 | =item B<daemon_detach (?%options)> |
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228 | |
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229 | This detaches the new child process from the terminal by doing |
230 | the following things. |
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231 | |
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232 | The C<%options> argument remains for backwards compatibility, but |
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233 | it is suggested that you use the attributes listed above instead. |
234 | |
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235 | =over 4 |
236 | |
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237 | =item Becomes a session leader |
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238 | |
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239 | This detaches the program from the controlling terminal, it is |
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240 | accomplished by calling POSIX::setsid. |
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241 | |
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242 | =item Performing the double-fork |
243 | |
244 | See below for information on how to change this part of the process. |
245 | |
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246 | =item Changes the current working directory to "/" |
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247 | |
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248 | This is standard daemon behavior, if you want a different working |
249 | directory then simply change it later in your daemons code. |
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250 | |
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251 | =item Clears the file creation mask. |
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252 | |
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253 | =item Closes all open file descriptors. |
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254 | |
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255 | See the I<dont_close_all_files> attribute for information on how to |
256 | change this part of the process. |
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257 | |
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258 | =item Reopen STDERR, STDOUT & STDIN to /dev/null |
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259 | |
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260 | This behavior can be controlled slightly though the MX_DAEMON_STDERR |
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261 | and MX_DAEMON_STDOUT environment variables. It will look for a filename |
262 | in either of these variables and redirect STDOUT and/or STDERR to those |
263 | files. This is useful for debugging and/or testing purposes. |
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264 | |
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265 | B<NOTE> |
266 | |
267 | If called from within the parent process (the is_daemon flag is set to |
268 | false), this method will simply return and do nothing. |
269 | |
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270 | =item B<daemonize (?%options)> |
271 | |
272 | This will simply call C<daemon_fork> followed by C<daemon_detach>. |
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273 | |
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274 | The C<%options> argument remains for backwards compatibility, but |
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275 | it is suggested that you use the attributes listed above instead. |
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276 | |
277 | =item meta() |
278 | |
279 | The C<meta()> method from L<Class::MOP::Class> |
280 | |
281 | =back |
282 | |
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283 | =back |
284 | |
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285 | =head1 STUFF YOU SHOULD READ |
286 | |
287 | =over 4 |
288 | |
289 | =item Note about double fork |
290 | |
291 | Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012> |
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292 | in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>, |
293 | it is not the definitive statement on the issue, but it's clear and well |
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294 | written enough so I decided to reproduce it here. |
295 | |
296 | The first fork accomplishes two things - allow the shell to return, |
297 | and allow you to do a setsid(). |
298 | |
299 | The setsid() removes yourself from your controlling terminal. You |
300 | see, before, you were still listed as a job of your previous process, |
301 | and therefore the user might accidentally send you a signal. setsid() |
302 | gives you a new session, and removes the existing controlling terminal. |
303 | |
304 | The problem is, you are now a session leader. As a session leader, if |
305 | you open a file descriptor that is a terminal, it will become your |
306 | controlling terminal (oops!). Therefore, the second fork makes you NOT |
307 | be a session leader. Only session leaders can acquire a controlling |
308 | terminal, so you can open up any file you wish without worrying that |
309 | it will make you a controlling terminal. |
310 | |
311 | So - first fork - allow shell to return, and permit you to call setsid() |
312 | |
313 | Second fork - prevent you from accidentally reacquiring a controlling |
314 | terminal. |
315 | |
316 | That said, you don't always want this to be the behavior, so you are |
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317 | free to specify otherwise using the I<no_double_fork> attribute. |
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318 | |
319 | =item Note about zombies |
320 | |
321 | Doing the double fork (see above) tends to get rid of your zombies since |
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322 | by the time you have double forked your daemon process is then owned by |
323 | the init process. However, sometimes the double-fork is more than you |
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324 | really need, and you want to keep your daemon processes a little closer |
325 | to you. In this case you have to watch out for zombies, you can avoid then |
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326 | by just setting the I<ignore_zombies> attribute (see above). |
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327 | |
328 | =back |
329 | |
330 | =head1 ENVIRONMENT VARIABLES |
331 | |
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332 | These variables are best just used for debugging and/or testing, but |
333 | not used for actual logging. For that, you should reopen STDOUT/ERR on |
334 | your own. |
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335 | |
336 | =over 4 |
337 | |
338 | =item B<MX_DAEMON_STDOUT> |
339 | |
340 | A filename to redirect the daemon STDOUT to. |
341 | |
342 | =item B<MX_DAEMON_STDERR> |
343 | |
344 | A filename to redirect the daemon STDERR to. |
345 | |
346 | =back |
347 | |
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348 | =head1 DEPENDENCIES |
349 | |
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350 | L<Moose::Role>, L<POSIX> |
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351 | |
352 | =head1 INCOMPATIBILITIES |
353 | |
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354 | None reported. |
355 | |
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356 | =head1 BUGS AND LIMITATIONS |
357 | |
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358 | No bugs have been reported. |
359 | |
360 | Please report any bugs or feature requests to |
361 | C<bug-acme-dahut-call@rt.cpan.org>, or through the web interface at |
362 | L<http://rt.cpan.org>. |
363 | |
364 | =head1 SEE ALSO |
365 | |
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366 | L<Proc::Daemon> |
367 | |
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368 | This code is based B<HEAVILY> on L<Proc::Daemon>, we originally |
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369 | depended on it, but we needed some more flexibility, so instead |
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370 | we just stole the code. |
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371 | |
372 | =head1 AUTHOR |
373 | |
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374 | Stevan Little C<< <stevan.little@iinteractive.com> >> |
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375 | |
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376 | =head1 LICENCE AND COPYRIGHT |
377 | |
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378 | Copyright (c) 2007-2011, Chris Prather C<< <perigrin@cpan.org> >>. All rights |
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379 | reserved. |
380 | |
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381 | Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood. |
382 | |
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383 | This module is free software; you can redistribute it and/or |
384 | modify it under the same terms as Perl itself. See L<perlartistic>. |
385 | |
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386 | =head1 DISCLAIMER OF WARRANTY |
387 | |
388 | BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY |
389 | FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN |
390 | OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES |
391 | PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER |
392 | EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
393 | WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE |
394 | ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH |
395 | YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL |
396 | NECESSARY SERVICING, REPAIR, OR CORRECTION. |
397 | |
398 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING |
399 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR |
400 | REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE |
401 | LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, |
402 | OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE |
403 | THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING |
404 | RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A |
405 | FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF |
406 | SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF |
407 | SUCH DAMAGES. |
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408 | |
409 | =cut |