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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.

The erlexec application has been in production use by Erlang and Elixir systems, and is stable.

See for more information.


If you find this project useful, please donate to:

  • Bitcoin: 12pt8TcoMWMkF6iY66VJQk95ntdN4pFihg
  • Ethereum: 0x268295486F258037CF53E504fcC1E67eba014218


Linux, Solaris, FreeBSD, OpenBSD, 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 either make sure that libcap-dev[el] library is installed or make sure that the user running the port program has sudo rights.

OS-specific libcap-dev installation instructions:

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

# NOTE: for disabling optimized build of exec-port, do the following instead:
$ OPTIMIZE=0 make

By default port program's implementation uses poll(2) call for event demultiplexing. If you prefer to use select(2), set the following environment variable:

$ USE_POLL=0 make


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