Open3 grants you access to stdin, stdout, stderr and a thread to wait the child process when running another program.
Example:
require "open3" include Open3 stdin, stdout, stderr, wait_thr = popen3('nroff -man')
::popen3 can also take a block which will receive stdin, stdout, stderr and wait_thr as parameters. This ensures stdin, stdout and stderr are closed and the process is terminated once the block exits.
Example:
require "open3" Open3.popen3('nroff -man') { |stdin, stdout, stderr, wait_thr| ... }
Open stdin, stdout, and stderr streams and start external executable. In addition, a thread for waiting the started process is noticed. The thread has a thread variable :pid which is the pid of the started process.
Non-block form:
stdin, stdout, stderr, wait_thr = Open3.popen3(cmd) pid = wait_thr[:pid] # pid of the started process. ... stdin.close # stdin, stdout and stderr should be closed in this form. stdout.close stderr.close exit_status = wait_thr.value # Process::Status object returned.
Block form:
Open3.popen3(cmd) { |stdin, stdout, stderr, wait_thr| ... }
The parameter cmd
is passed directly to Kernel#spawn.
wait_thr.value waits the termination of the process. The block form also waits the process when it returns.
Closing stdin, stdout and stderr does not wait the process.
# File open3.rb, line 62 def popen3(*cmd) pw = IO::pipe # pipe[0] for read, pipe[1] for write pr = IO::pipe pe = IO::pipe pid = spawn(*cmd, STDIN=>pw[0], STDOUT=>pr[1], STDERR=>pe[1]) wait_thr = Process.detach(pid) pw[0].close pr[1].close pe[1].close pi = [pw[1], pr[0], pe[0], wait_thr] pw[1].sync = true if defined? yield begin return yield(*pi) ensure [pw[1], pr[0], pe[0]].each{|p| p.close unless p.closed?} wait_thr.join end end pi end