Re: Logging stdout/stderr/stdin of an spawn process (Open4::spawn)
- From: Ed Hames <ehames@xxxxxxxxx>
- Date: Tue, 6 May 2008 13:17:42 -0700 (PDT)
On Apr 29, 12:05 pm, Edgardo Hames <eha...@xxxxxxxxx> wrote:
I need to log all the input (typed by the user) and the stdout/stderr
of a process. The #script method below should behave pretty much like
the Unix script application. This way, my application can issue
several commands, show their output to the user an let them whatever
is needed.
def script cmd, log
# prepare $stdin to save its content into log
# prepare $stdout to save its content into log
# prepare $stderr to save its content into log
status = Open4::spawn cmd, 'stdin' => $stdin, 'stdout' =>
$stdout, 'stderr' => $stderr
end
I finally managed to do it. Open4::spawn allows any object to be used
as stdin/stdout/stderr as long as they support 'each', 'read', or
'to_s' or '<<'. So I just created a wrapper class that encapsulates
two descriptors logging al I/O operations.
Best regards,
Edgardo
# BEGIN SCRIPT
require 'rubygems'
require 'open4'
class LoggingIO
def initialize io, log
@io = io
@log = log
end
def gets(sep_string=$/)
res = @io.gets(sep_string)
log res
res
end
def << obj
res = @io << obj
log obj
res
end
def log obj
str = obj ? obj.to_s : "(nil)\n"
@log << str
end
private :log
end
def execute cmd, logfile = nil
log = nil
stdin = $stdin
stdout = $stdout
stderr = $stderr
if (logfile)
log = File.open(logfile, 'a+')
stdin = LoggingIO.new($stdin, log)
stdout = LoggingIO.new($stdout, log)
stderr = LoggingIO.new($stderr, log)
end
status = Open4::spawn cmd, 'stdin' => stdin, 'stdout' =>
stdout, 'stderr' => stderr
log.close if log
status
end
# END SCRIPT
.
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