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Execute and control OS processes from Erlang/OTP.

This project implements an Erlang application with a C++ port program that gives light-weight Erlang processes fine-grain control over execution of OS processes.

The following features are supported:

  • Start/stop OS commands and get their OS process IDs, and termination reason (exit code, signal number, core dump status).
  • Manage/monitor externally started OS processes.
  • Execute OS processes synchronously and asynchronously.
  • Set OS command's working directory, environment, process group, effective user, process priority.
  • Provide custom termination command for killing a process or relying on default SIGTERM/SIGKILL behavior.
  • Specify custom timeout for SIGKILL after the termination command or SIGTERM was executed and the running OS child process is still alive.
  • Link an Erlang processes to OS processes (via intermediate Erlang Pids that are linked to an associated OS process).
  • Monitor termination of OS processes.
  • Terminate all processes beloging to an OS process group.
  • Kill processes belonging to an OS process group at process exit.
  • Communicate with an OS process via its STDIN.
  • Redirect STDOUT and STDERR of an OS process to a file, erlang process, or a custom function. When redirected to a file, the file can be open in append/truncate mode, and given creation access mask.
  • Run interactive processes with psudo-terminal pty support.
  • Execute OS processes under different user credentials (using Linux capabilities).
  • Perform proper cleanup of OS child processes at port program termination time.

This application provides significantly better control over OS processes than built-in erlang:open_port/2 command with a {spawn, Command} option, and performs proper OS child process cleanup when the emulator exits.

See for more information.


Linux, Solaris, FreeBSD, MacOS X




Make sure you have rebar ( or installed locally and the rebar script is in the path.

If you are deploying the application on Linux and would like to take advantage of exec-port running tasks using effective user IDs different from the real user ID that started exec-port, then make sure that libcap-dev[el] library is installed.

OS-specific libcap-dev installation instructions:

  • Fedora, CentOS: "yum install libcap-devel"
  • Ubuntu: "apt-get install libcap-dev"
$ git clone
$ make

# NOTE: for enabling optimized build of exec-port, do the following instead:
$ OPTIMIZE=true make


The program is distributed under BSD license. Copyright (c) 2003 Serge Aleynikov