o:$YARD::CodeObjects::MethodObject: @scope:
instance:@visibility: public:
@pathI"Kernel#spawn:EF:@parameters[�: @files[[I"process.c; T0: @current_file_has_commentsF:
@name:
spawn:@source_type:c:
@tags[�:@docstringIC:YARD::Docstring"�#spawn executes specified command and return its pid.
This method doesn't wait for end of the command.
The parent process should
use <code>Process.wait</code> to collect
the termination status of its child or
use <code>Process.detach</code> to register
disinterest in their status;
otherwise, the operating system may accumulate zombie processes.
spawn has bunch of options to specify process attributes:
env: hash
name => val : set the environment variable
name => nil : unset the environment variable
command...:
commandline : command line string which is passed to the standard shell
cmdname, arg1, ... : command name and one or more arguments (no shell)
[cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
options: hash
clearing environment variables:
:unsetenv_others => true : clear environment variables except specified by env
:unsetenv_others => false : don't clear (default)
process group:
:pgroup => true or 0 : make a new process group
:pgroup => pgid : join to specified process group
:pgroup => nil : don't change the process group (default)
resource limit: resourcename is core, cpu, data, etc. See Process.setrlimit.
:rlimit_resourcename => limit
:rlimit_resourcename => [cur_limit, max_limit]
current directory:
:chdir => str
umask:
:umask => int
redirection:
key:
FD : single file descriptor in child process
[FD, FD, ...] : multiple file descriptor in child process
value:
FD : redirect to the file descriptor in parent process
string : redirect to file with open(string, "r" or "w")
[string] : redirect to file with open(string, File::RDONLY)
[string, open_mode] : redirect to file with open(string, open_mode, 0644)
[string, open_mode, perm] : redirect to file with open(string, open_mode, perm)
[:child, FD] : redirect to the redirected file descriptor
:close : close the file descriptor in child process
FD is one of follows
:in : the file descriptor 0 which is the standard input
:out : the file descriptor 1 which is the standard output
:err : the file descriptor 2 which is the standard error
integer : the file descriptor of specified the integer
io : the file descriptor specified as io.fileno
file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
:close_others => false : inherit fds (default for system and exec)
:close_others => true : don't inherit (default for spawn and IO.popen)
If a hash is given as +env+, the environment is
updated by +env+ before <code>exec(2)</code> in the child process.
If a pair in +env+ has nil as the value, the variable is deleted.
# set FOO as BAR and unset BAZ.
pid = spawn({"FOO"=>"BAR", "BAZ"=>nil}, command)
If a hash is given as +options+,
it specifies
process group,
resource limit,
current directory,
umask and
redirects for the child process.
Also, it can be specified to clear environment variables.
The <code>:unsetenv_others</code> key in +options+ specifies
to clear environment variables, other than specified by +env+.
pid = spawn(command, :unsetenv_others=>true) # no environment variable
pid = spawn({"FOO"=>"BAR"}, command, :unsetenv_others=>true) # FOO only
The <code>:pgroup</code> key in +options+ specifies a process group.
The corresponding value should be true, zero or positive integer.
true and zero means the process should be a process leader of a new
process group.
Other values specifies a process group to be belongs.
pid = spawn(command, :pgroup=>true) # process leader
pid = spawn(command, :pgroup=>10) # belongs to the process group 10
The <code>:rlimit_</code><em>foo</em> key specifies a resource limit.
<em>foo</em> should be one of resource types such as <code>core</code>.
The corresponding value should be an integer or an array which have one or
two integers: same as cur_limit and max_limit arguments for
Process.setrlimit.
cur, max = Process.getrlimit(:CORE)
pid = spawn(command, :rlimit_core=>[0,max]) # disable core temporary.
pid = spawn(command, :rlimit_core=>max) # enable core dump
pid = spawn(command, :rlimit_core=>0) # never dump core.
The <code>:chdir</code> key in +options+ specifies the current directory.
pid = spawn(command, :chdir=>"/var/tmp")
The <code>:umask</code> key in +options+ specifies the umask.
pid = spawn(command, :umask=>077)
The :in, :out, :err, a fixnum, an IO and an array key specifies a redirection.
The redirection maps a file descriptor in the child process.
For example, stderr can be merged into stdout as follows:
pid = spawn(command, :err=>:out)
pid = spawn(command, 2=>1)
pid = spawn(command, STDERR=>:out)
pid = spawn(command, STDERR=>STDOUT)
The hash keys specifies a file descriptor
in the child process started by <code>spawn</code>.
:err, 2 and STDERR specifies the standard error stream (stderr).
The hash values specifies a file descriptor
in the parent process which invokes <code>spawn</code>.
:out, 1 and STDOUT specifies the standard output stream (stdout).
In the above example,
the standard output in the child process is not specified.
So it is inherited from the parent process.
The standard input stream (stdin) can be specified by :in, 0 and STDIN.
A filename can be specified as a hash value.
pid = spawn(command, :in=>"/dev/null") # read mode
pid = spawn(command, :out=>"/dev/null") # write mode
pid = spawn(command, :err=>"log") # write mode
pid = spawn(command, 3=>"/dev/null") # read mode
For stdout and stderr,
it is opened in write mode.
Otherwise read mode is used.
For specifying flags and permission of file creation explicitly,
an array is used instead.
pid = spawn(command, :in=>["file"]) # read mode is assumed
pid = spawn(command, :in=>["file", "r"])
pid = spawn(command, :out=>["log", "w"]) # 0644 assumed
pid = spawn(command, :out=>["log", "w", 0600])
pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600])
The array specifies a filename, flags and permission.
The flags can be a string or an integer.
If the flags is omitted or nil, File::RDONLY is assumed.
The permission should be an integer.
If the permission is omitted or nil, 0644 is assumed.
If an array of IOs and integers are specified as a hash key,
all the elements are redirected.
# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, [:out, :err]=>["log", "w"])
Another way to merge multiple file descriptors is [:child, fd].
\[:child, fd] means the file descriptor in the child process.
This is different from fd.
For example, :err=>:out means redirecting child stderr to parent stdout.
But :err=>[:child, :out] means redirecting child stderr to child stdout.
They differs if stdout is redirected in the child process as follows.
# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out])
\[:child, :out] can be used to merge stderr into stdout in IO.popen.
In this case, IO.popen redirects stdout to a pipe in the child process
and [:child, :out] refers the redirected stdout.
io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]])
p io.read #=> "out\nerr\n"
spawn closes all non-standard unspecified descriptors by default.
The "standard" descriptors are 0, 1 and 2.
This behavior is specified by :close_others option.
:close_others doesn't affect the standard descriptors which are
closed only if :close is specified explicitly.
pid = spawn(command, :close_others=>true) # close 3,4,5,... (default)
pid = spawn(command, :close_others=>false) # don't close 3,4,5,...
:close_others is true by default for spawn and IO.popen.
So IO.pipe and spawn can be used as IO.popen.
# similar to r = IO.popen(command)
r, w = IO.pipe
pid = spawn(command, :out=>w) # r, w is closed in the child process.
w.close
:close is specified as a hash value to close a fd individually.
f = open(foo)
system(command, f=>:close) # don't inherit f.
If a file descriptor need to be inherited,
io=>io can be used.
# valgrind has --log-fd option for log destination.
# log_w=>log_w indicates log_w.fileno inherits to child process.
log_r, log_w = IO.pipe
pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w)
log_w.close
p log_r.read
It is also possible to exchange file descriptors.
pid = spawn(command, :out=>:err, :err=>:out)
The hash keys specify file descriptors in the child process.
The hash values specifies file descriptors in the parent process.
So the above specifies exchanging stdout and stderr.
Internally, +spawn+ uses an extra file descriptor to resolve such cyclic
file descriptor mapping.
See <code>Kernel.exec</code> for the standard shell. ; F: @objectIu:YARD::StubProxyKernel#spawn; F:
@summary0:@ref_tags[�;[o: YARD::Tags::OverloadTag
:@tag_nameI"
overload; F:
@text0;;: @types0:@signatureI"(spawn([env,] command... [,options]); F;IC;"� ; F;Iu;Kernel#spawn; F;0;[�;[�: @allI"�; F; [[:[env,][,options]0;Iu;Kernel#spawn; Fo;
;I"
overload; F; 0;;; 0; I"(spawn([env,] command... [,options]); F;IC;"� ; F;Iu;Kernel#spawn; F;0;[�;[�; I"�; F; [[; 0;Iu;Kernel#spawn; F; I" $spawn executes specified command and return its pid.
This method doesn't wait for end of the command.
The parent process should
use <code>Process.wait</code> to collect
the termination status of its child or
use <code>Process.detach</code> to register
disinterest in their status;
otherwise, the operating system may accumulate zombie processes.
spawn has bunch of options to specify process attributes:
env: hash
name => val : set the environment variable
name => nil : unset the environment variable
command...:
commandline : command line string which is passed to the standard shell
cmdname, arg1, ... : command name and one or more arguments (no shell)
[cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
options: hash
clearing environment variables:
:unsetenv_others => true : clear environment variables except specified by env
:unsetenv_others => false : don't clear (default)
process group:
:pgroup => true or 0 : make a new process group
:pgroup => pgid : join to specified process group
:pgroup => nil : don't change the process group (default)
resource limit: resourcename is core, cpu, data, etc. See Process.setrlimit.
:rlimit_resourcename => limit
:rlimit_resourcename => [cur_limit, max_limit]
current directory:
:chdir => str
umask:
:umask => int
redirection:
key:
FD : single file descriptor in child process
[FD, FD, ...] : multiple file descriptor in child process
value:
FD : redirect to the file descriptor in parent process
string : redirect to file with open(string, "r" or "w")
[string] : redirect to file with open(string, File::RDONLY)
[string, open_mode] : redirect to file with open(string, open_mode, 0644)
[string, open_mode, perm] : redirect to file with open(string, open_mode, perm)
[:child, FD] : redirect to the redirected file descriptor
:close : close the file descriptor in child process
FD is one of follows
:in : the file descriptor 0 which is the standard input
:out : the file descriptor 1 which is the standard output
:err : the file descriptor 2 which is the standard error
integer : the file descriptor of specified the integer
io : the file descriptor specified as io.fileno
file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
:close_others => false : inherit fds (default for system and exec)
:close_others => true : don't inherit (default for spawn and IO.popen)
If a hash is given as +env+, the environment is
updated by +env+ before <code>exec(2)</code> in the child process.
If a pair in +env+ has nil as the value, the variable is deleted.
# set FOO as BAR and unset BAZ.
pid = spawn({"FOO"=>"BAR", "BAZ"=>nil}, command)
If a hash is given as +options+,
it specifies
process group,
resource limit,
current directory,
umask and
redirects for the child process.
Also, it can be specified to clear environment variables.
The <code>:unsetenv_others</code> key in +options+ specifies
to clear environment variables, other than specified by +env+.
pid = spawn(command, :unsetenv_others=>true) # no environment variable
pid = spawn({"FOO"=>"BAR"}, command, :unsetenv_others=>true) # FOO only
The <code>:pgroup</code> key in +options+ specifies a process group.
The corresponding value should be true, zero or positive integer.
true and zero means the process should be a process leader of a new
process group.
Other values specifies a process group to be belongs.
pid = spawn(command, :pgroup=>true) # process leader
pid = spawn(command, :pgroup=>10) # belongs to the process group 10
The <code>:rlimit_</code><em>foo</em> key specifies a resource limit.
<em>foo</em> should be one of resource types such as <code>core</code>.
The corresponding value should be an integer or an array which have one or
two integers: same as cur_limit and max_limit arguments for
Process.setrlimit.
cur, max = Process.getrlimit(:CORE)
pid = spawn(command, :rlimit_core=>[0,max]) # disable core temporary.
pid = spawn(command, :rlimit_core=>max) # enable core dump
pid = spawn(command, :rlimit_core=>0) # never dump core.
The <code>:chdir</code> key in +options+ specifies the current directory.
pid = spawn(command, :chdir=>"/var/tmp")
The <code>:umask</code> key in +options+ specifies the umask.
pid = spawn(command, :umask=>077)
The :in, :out, :err, a fixnum, an IO and an array key specifies a redirection.
The redirection maps a file descriptor in the child process.
For example, stderr can be merged into stdout as follows:
pid = spawn(command, :err=>:out)
pid = spawn(command, 2=>1)
pid = spawn(command, STDERR=>:out)
pid = spawn(command, STDERR=>STDOUT)
The hash keys specifies a file descriptor
in the child process started by <code>spawn</code>.
:err, 2 and STDERR specifies the standard error stream (stderr).
The hash values specifies a file descriptor
in the parent process which invokes <code>spawn</code>.
:out, 1 and STDOUT specifies the standard output stream (stdout).
In the above example,
the standard output in the child process is not specified.
So it is inherited from the parent process.
The standard input stream (stdin) can be specified by :in, 0 and STDIN.
A filename can be specified as a hash value.
pid = spawn(command, :in=>"/dev/null") # read mode
pid = spawn(command, :out=>"/dev/null") # write mode
pid = spawn(command, :err=>"log") # write mode
pid = spawn(command, 3=>"/dev/null") # read mode
For stdout and stderr,
it is opened in write mode.
Otherwise read mode is used.
For specifying flags and permission of file creation explicitly,
an array is used instead.
pid = spawn(command, :in=>["file"]) # read mode is assumed
pid = spawn(command, :in=>["file", "r"])
pid = spawn(command, :out=>["log", "w"]) # 0644 assumed
pid = spawn(command, :out=>["log", "w", 0600])
pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600])
The array specifies a filename, flags and permission.
The flags can be a string or an integer.
If the flags is omitted or nil, File::RDONLY is assumed.
The permission should be an integer.
If the permission is omitted or nil, 0644 is assumed.
If an array of IOs and integers are specified as a hash key,
all the elements are redirected.
# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, [:out, :err]=>["log", "w"])
Another way to merge multiple file descriptors is [:child, fd].
\[:child, fd] means the file descriptor in the child process.
This is different from fd.
For example, :err=>:out means redirecting child stderr to parent stdout.
But :err=>[:child, :out] means redirecting child stderr to child stdout.
They differs if stdout is redirected in the child process as follows.
# stdout and stderr is redirected to log file.
# The file "log" is opened just once.
pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out])
\[:child, :out] can be used to merge stderr into stdout in IO.popen.
In this case, IO.popen redirects stdout to a pipe in the child process
and [:child, :out] refers the redirected stdout.
io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]])
p io.read #=> "out\nerr\n"
spawn closes all non-standard unspecified descriptors by default.
The "standard" descriptors are 0, 1 and 2.
This behavior is specified by :close_others option.
:close_others doesn't affect the standard descriptors which are
closed only if :close is specified explicitly.
pid = spawn(command, :close_others=>true) # close 3,4,5,... (default)
pid = spawn(command, :close_others=>false) # don't close 3,4,5,...
:close_others is true by default for spawn and IO.popen.
So IO.pipe and spawn can be used as IO.popen.
# similar to r = IO.popen(command)
r, w = IO.pipe
pid = spawn(command, :out=>w) # r, w is closed in the child process.
w.close
:close is specified as a hash value to close a fd individually.
f = open(foo)
system(command, f=>:close) # don't inherit f.
If a file descriptor need to be inherited,
io=>io can be used.
# valgrind has --log-fd option for log destination.
# log_w=>log_w indicates log_w.fileno inherits to child process.
log_r, log_w = IO.pipe
pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w)
log_w.close
p log_r.read
It is also possible to exchange file descriptors.
pid = spawn(command, :out=>:err, :err=>:out)
The hash keys specify file descriptors in the child process.
The hash values specifies file descriptors in the parent process.
So the above specifies exchanging stdout and stderr.
Internally, +spawn+ uses an extra file descriptor to resolve such cyclic
file descriptor mapping.
See <code>Kernel.exec</code> for the standard shell.
@overload spawn([env,] command... [,options])
@overload spawn([env,] command... [,options]); F:@namespaceIu; Kernel; F:@docstring_extra0: @sourceI"y)/*
* call-seq:
* spawn([env,] command... [,options]) -> pid
* Process.spawn([env,] command... [,options]) -> pid
*
* spawn executes specified command and return its pid.
*
* This method doesn't wait for end of the command.
* The parent process should
* use <code>Process.wait</code> to collect
* the termination status of its child or
* use <code>Process.detach</code> to register
* disinterest in their status;
* otherwise, the operating system may accumulate zombie processes.
*
* spawn has bunch of options to specify process attributes:
*
* env: hash
* name => val : set the environment variable
* name => nil : unset the environment variable
* command...:
* commandline : command line string which is passed to the standard shell
* cmdname, arg1, ... : command name and one or more arguments (no shell)
* [cmdname, argv0], arg1, ... : command name, argv[0] and zero or more arguments (no shell)
* options: hash
* clearing environment variables:
* :unsetenv_others => true : clear environment variables except specified by env
* :unsetenv_others => false : don't clear (default)
* process group:
* :pgroup => true or 0 : make a new process group
* :pgroup => pgid : join to specified process group
* :pgroup => nil : don't change the process group (default)
* resource limit: resourcename is core, cpu, data, etc. See Process.setrlimit.
* :rlimit_resourcename => limit
* :rlimit_resourcename => [cur_limit, max_limit]
* current directory:
* :chdir => str
* umask:
* :umask => int
* redirection:
* key:
* FD : single file descriptor in child process
* [FD, FD, ...] : multiple file descriptor in child process
* value:
* FD : redirect to the file descriptor in parent process
* string : redirect to file with open(string, "r" or "w")
* [string] : redirect to file with open(string, File::RDONLY)
* [string, open_mode] : redirect to file with open(string, open_mode, 0644)
* [string, open_mode, perm] : redirect to file with open(string, open_mode, perm)
* [:child, FD] : redirect to the redirected file descriptor
* :close : close the file descriptor in child process
* FD is one of follows
* :in : the file descriptor 0 which is the standard input
* :out : the file descriptor 1 which is the standard output
* :err : the file descriptor 2 which is the standard error
* integer : the file descriptor of specified the integer
* io : the file descriptor specified as io.fileno
* file descriptor inheritance: close non-redirected non-standard fds (3, 4, 5, ...) or not
* :close_others => false : inherit fds (default for system and exec)
* :close_others => true : don't inherit (default for spawn and IO.popen)
*
* If a hash is given as +env+, the environment is
* updated by +env+ before <code>exec(2)</code> in the child process.
* If a pair in +env+ has nil as the value, the variable is deleted.
*
* # set FOO as BAR and unset BAZ.
* pid = spawn({"FOO"=>"BAR", "BAZ"=>nil}, command)
*
* If a hash is given as +options+,
* it specifies
* process group,
* resource limit,
* current directory,
* umask and
* redirects for the child process.
* Also, it can be specified to clear environment variables.
*
* The <code>:unsetenv_others</code> key in +options+ specifies
* to clear environment variables, other than specified by +env+.
*
* pid = spawn(command, :unsetenv_others=>true) # no environment variable
* pid = spawn({"FOO"=>"BAR"}, command, :unsetenv_others=>true) # FOO only
*
* The <code>:pgroup</code> key in +options+ specifies a process group.
* The corresponding value should be true, zero or positive integer.
* true and zero means the process should be a process leader of a new
* process group.
* Other values specifies a process group to be belongs.
*
* pid = spawn(command, :pgroup=>true) # process leader
* pid = spawn(command, :pgroup=>10) # belongs to the process group 10
*
* The <code>:rlimit_</code><em>foo</em> key specifies a resource limit.
* <em>foo</em> should be one of resource types such as <code>core</code>.
* The corresponding value should be an integer or an array which have one or
* two integers: same as cur_limit and max_limit arguments for
* Process.setrlimit.
*
* cur, max = Process.getrlimit(:CORE)
* pid = spawn(command, :rlimit_core=>[0,max]) # disable core temporary.
* pid = spawn(command, :rlimit_core=>max) # enable core dump
* pid = spawn(command, :rlimit_core=>0) # never dump core.
*
* The <code>:chdir</code> key in +options+ specifies the current directory.
*
* pid = spawn(command, :chdir=>"/var/tmp")
*
* The <code>:umask</code> key in +options+ specifies the umask.
*
* pid = spawn(command, :umask=>077)
*
* The :in, :out, :err, a fixnum, an IO and an array key specifies a redirection.
* The redirection maps a file descriptor in the child process.
*
* For example, stderr can be merged into stdout as follows:
*
* pid = spawn(command, :err=>:out)
* pid = spawn(command, 2=>1)
* pid = spawn(command, STDERR=>:out)
* pid = spawn(command, STDERR=>STDOUT)
*
* The hash keys specifies a file descriptor
* in the child process started by <code>spawn</code>.
* :err, 2 and STDERR specifies the standard error stream (stderr).
*
* The hash values specifies a file descriptor
* in the parent process which invokes <code>spawn</code>.
* :out, 1 and STDOUT specifies the standard output stream (stdout).
*
* In the above example,
* the standard output in the child process is not specified.
* So it is inherited from the parent process.
*
* The standard input stream (stdin) can be specified by :in, 0 and STDIN.
*
* A filename can be specified as a hash value.
*
* pid = spawn(command, :in=>"/dev/null") # read mode
* pid = spawn(command, :out=>"/dev/null") # write mode
* pid = spawn(command, :err=>"log") # write mode
* pid = spawn(command, 3=>"/dev/null") # read mode
*
* For stdout and stderr,
* it is opened in write mode.
* Otherwise read mode is used.
*
* For specifying flags and permission of file creation explicitly,
* an array is used instead.
*
* pid = spawn(command, :in=>["file"]) # read mode is assumed
* pid = spawn(command, :in=>["file", "r"])
* pid = spawn(command, :out=>["log", "w"]) # 0644 assumed
* pid = spawn(command, :out=>["log", "w", 0600])
* pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600])
*
* The array specifies a filename, flags and permission.
* The flags can be a string or an integer.
* If the flags is omitted or nil, File::RDONLY is assumed.
* The permission should be an integer.
* If the permission is omitted or nil, 0644 is assumed.
*
* If an array of IOs and integers are specified as a hash key,
* all the elements are redirected.
*
* # stdout and stderr is redirected to log file.
* # The file "log" is opened just once.
* pid = spawn(command, [:out, :err]=>["log", "w"])
*
* Another way to merge multiple file descriptors is [:child, fd].
* \[:child, fd] means the file descriptor in the child process.
* This is different from fd.
* For example, :err=>:out means redirecting child stderr to parent stdout.
* But :err=>[:child, :out] means redirecting child stderr to child stdout.
* They differs if stdout is redirected in the child process as follows.
*
* # stdout and stderr is redirected to log file.
* # The file "log" is opened just once.
* pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out])
*
* \[:child, :out] can be used to merge stderr into stdout in IO.popen.
* In this case, IO.popen redirects stdout to a pipe in the child process
* and [:child, :out] refers the redirected stdout.
*
* io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]])
* p io.read #=> "out\nerr\n"
*
* spawn closes all non-standard unspecified descriptors by default.
* The "standard" descriptors are 0, 1 and 2.
* This behavior is specified by :close_others option.
* :close_others doesn't affect the standard descriptors which are
* closed only if :close is specified explicitly.
*
* pid = spawn(command, :close_others=>true) # close 3,4,5,... (default)
* pid = spawn(command, :close_others=>false) # don't close 3,4,5,...
*
* :close_others is true by default for spawn and IO.popen.
*
* So IO.pipe and spawn can be used as IO.popen.
*
* # similar to r = IO.popen(command)
* r, w = IO.pipe
* pid = spawn(command, :out=>w) # r, w is closed in the child process.
* w.close
*
* :close is specified as a hash value to close a fd individually.
*
* f = open(foo)
* system(command, f=>:close) # don't inherit f.
*
* If a file descriptor need to be inherited,
* io=>io can be used.
*
* # valgrind has --log-fd option for log destination.
* # log_w=>log_w indicates log_w.fileno inherits to child process.
* log_r, log_w = IO.pipe
* pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w)
* log_w.close
* p log_r.read
*
* It is also possible to exchange file descriptors.
*
* pid = spawn(command, :out=>:err, :err=>:out)
*
* The hash keys specify file descriptors in the child process.
* The hash values specifies file descriptors in the parent process.
* So the above specifies exchanging stdout and stderr.
* Internally, +spawn+ uses an extra file descriptor to resolve such cyclic
* file descriptor mapping.
*
* See <code>Kernel.exec</code> for the standard shell.
*/
static VALUE
rb_f_spawn(int argc, VALUE *argv)
{
rb_pid_t pid;
char errmsg[CHILD_ERRMSG_BUFLEN] = { '\0' };
struct rb_exec_arg earg;
pid = rb_spawn_process(&earg, rb_exec_arg_prepare(&earg, argc, argv, TRUE), errmsg, sizeof(errmsg));
if (pid == -1) {
const char *prog = errmsg;
if (!prog[0] && !(prog = earg.prog) && earg.argc) {
prog = RSTRING_PTR(earg.argv[0]);
}
rb_sys_fail(prog);
}
#if defined(HAVE_FORK) || defined(HAVE_SPAWNV)
return PIDT2NUM(pid);
#else
return Qnil;
#endif
}; F