1No::Worries::Proc(3) User Contributed Perl Documentation No::Worries::Proc(3)
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6 No::Worries::Proc - process handling without worries
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9 use No::Worries::Proc qw(proc_run proc_create proc_monitor proc_detach);
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11 # simple interface to execute a command
12 $status = proc_run(command => [ "foo", "-x", 7 ]);
13 printf("foo exited with %d\n", $status);
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15 # idem but with output redirection and more information
16 %proc = proc_run(command => [ qw(uname -a) ], stdout => \$output);
17 printf("process %d output is %s\n", $proc->{pid}, $output);
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19 # start two process and wait for them to finish
20 $p1 = proc_create(
21 command => \@cmd1,
22 timeout => 5, # to be killed if still running after 5s
23 stderr => "/dev/null", # discard stderr
24 );
25 $p2 = proc_create(
26 command => \@cmd2,
27 stdout => \$output, # get stdout+stderr in $output
28 stderr => "", # merge stderr with stdout
29 );
30 proc_monitor([ $p1, $p2 ], timeout => 10);
31 printf("%d finished\n", $p1->{pid}) if $p1->{stop};
32 printf("%d finished\n", $p2->{pid}) if $p2->{stop};
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34 # detach ourself to run as a daemon
35 proc_detach(callback => sub { print("started with pid $_[0]\n")});
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38 This module eases process handling by providing high level functions to
39 start, monitor and stop processes. All the functions die() on error.
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41 It also provides the $No::Worries::Proc::Transient variable that
42 indicates, after a fork(), which process is transient and is about to
43 exec() or exit(). This is useful for instance in an END block:
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45 END {
46 # remove our pid file unless we are transient
47 pf_unset($pidfile) unless $No::Worries::Proc::Transient;
48 }
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51 This module provides the following functions (none of them being
52 exported by default):
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54 proc_output(COMMAND...)
55 execute the given command, capture its output (stdout only), check
56 its exit code (report an error if it is not zero) and return the
57 captured output; this is similar to Perl's qx() operator but
58 bypassing the shell and always checking the exit code
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60 proc_create(OPTIONS)
61 create a new process that will execute the given command and return
62 a hash reference representing this process (see the "PROCESS
63 STRUCTURE" sections for more information), to be given to
64 proc_monitor() or proc_terminate() afterwards; supported options:
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66 · "command": the command to execute, it must be an array
67 reference
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69 · "cwd": the current working directory of the new process
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71 · "timeout": the maximum number of seconds that the process is
72 allowed to take to run (can be fractional); after this, it may
73 be killed by proc_monitor()
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75 · "kill": how to "gently" kill the process, see below
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77 · "stdin": what to do with stdin, see below
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79 · "stdout": what to do with stdout, see below
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81 · "stderr": what to do with stderr, see below
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83 proc_terminate(PROC[, OPTIONS])
84 terminate the given process (PROC can be either a process structure
85 or simply a process id) by sending signals and waiting for the
86 process to finish; supported options:
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88 · "kill": how to "gently" kill the process, see below
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90 proc_monitor(PROCS[, OPTIONS])
91 monitor the given process(es) (as created by proc_create()); PROCS
92 can be either a single process or a reference to a list of
93 processes; supported options:
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95 · "timeout": the maximum number of seconds that proc_monitor()
96 should take, can be fractional
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98 · "bufsize": the buffer size to use for I/O operations (default:
99 8192)
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101 · "deaths": the minimum number of process deaths that
102 proc_monitor() will wait for before returning
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104 proc_run(OPTIONS)
105 execute the given process (i.e. create and monitor it until
106 termination) and return its status (i.e. $?) in scalar context or
107 the whole process structure in list context; supported options: the
108 ones of proc_create()
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110 proc_detach([OPTIONS])
111 detach the current process so that it becomes a daemon running in
112 the background (this implies forking and re-opening std*);
113 supported options:
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115 · "callback": code reference that will be executed by the parent
116 process just before exiting and will be given the child pid
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119 The process structure (hash) used in this module has the following
120 fields:
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122 · "command": the command being executed, as an array reference
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124 · "pid": the process id
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126 · "start": the start time, in fractional seconds
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128 · "stop": the stop time, in fractional seconds
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130 · "status": the status (i.e. $?)
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132 · "timeout": true if the process has been killed because of timeout
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135 When using the "stdin" option of proc_create(), the value can be:
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137 · a string: input will be read from the given file name
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139 · a scalar reference: input will be the scalar itself
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141 When using the "stdout" and "stderr" options of proc_create(), the
142 value can be:
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144 · a string: output will be written to the given file name
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146 · a scalar reference: output will be stored in the scalar
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148 · a code reference: each time new output is available, the code will
149 be called with two parameters: the process structure and the new
150 output
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152 In addition, "stderr" can also be given an empty string that means that
153 stderr should be merged with stdout.
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156 Both proc_create() and proc_terminate() can be given a "kill" option
157 that specifies how the process should be killed.
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159 The specification is a string containing a space separated list of
160 signal/grace couples, meaning: send the given signal and wait a bit for
161 the process to finish.
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163 If not specified, the default is "TERM/1 INT/1 QUIT/1", meaning:
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165 · send SIGTERM and wait up to 1 second for the process to finish
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167 · if the process is still alive, send SIGINT and wait up to 1 second
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169 · if the process is still alive, send SIGQUIT and wait up to 1 second
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171 · if the process is still alive, send SIGKILL (implicit)
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174 This module uses the following global variables (none of them being
175 exported):
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177 $Transient
178 true if the process is about to exec() or exit(), there is usually
179 no need to perform any cleanup (e.g. in an END block) for this kind
180 of process
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183 No::Worries.
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186 Lionel Cons <http://cern.ch/lionel.cons>
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188 Copyright (C) CERN 2012-2017
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192perl v5.28.1 2017-08-01 No::Worries::Proc(3)