Class | POSIX::Spawn::Child |
In: |
lib/posix/spawn/child.rb
|
Parent: | Object |
POSIX::Spawn::Child includes logic for executing child processes and reading/writing from their standard input, output, and error streams. It‘s designed to take all input in a single string and provides all output (stderr and stdout) as single strings and is therefore not well-suited to streaming large quantities of data in and out of commands.
Create and run a process to completion:
>> child = POSIX::Spawn::Child.new('git', '--help')
Retrieve stdout or stderr output:
>> child.out => "usage: git [--version] [--exec-path[=GIT_EXEC_PATH]]\n ..." >> child.err => ""
Check process exit status information:
>> child.status => #<Process::Status: pid=80718,exited(0)>
To write data on the new process‘s stdin immediately after spawning:
>> child = POSIX::Spawn::Child.new('bc', :input => '40 + 2') >> child.out "42\n"
Q: Why use POSIX::Spawn::Child instead of popen3, hand rolled fork/exec code, or Process::spawn?
BUFSIZE | = | (32 * 1024) | Maximum buffer size for reading |
err | [R] | All data written to the child process‘s stderr stream as a String. |
out | [R] | All data written to the child process‘s stdout stream as a String. |
runtime | [R] | Total command execution time (wall-clock time) |
status | [R] | A Process::Status object with information on how the child exited. |
Spawn a new process, write all input and read all output, and wait for the program to exit. Supports the standard spawn interface as described in the POSIX::Spawn module documentation:
new([env], command, [argv1, ...], [options])
The following options are supported in addition to the standard POSIX::Spawn options:
:input => str Write str to the new process's standard input. :timeout => int Maximum number of seconds to allow the process to execute before aborting with a TimeoutExceeded exception. :max => total Maximum number of bytes of output to allow the process to generate before aborting with a MaximumOutputExceeded exception.
Returns a new Child instance whose underlying process has already executed to completion. The out, err, and status attributes are immediately available.