Howto perform a fresh install of OCaml with OPAM
Posted at 03/20/17 - 04:03 PM

 I recently had to set up a fresh installation of OCaml, using OPAM, in my home directory on a Linux machine. I followed the hints given at for installing OPAM, and used a simple OPAM command to execute to install OCaml.

Here is the summary of my installation, in case you want to do the same by yourself. Note that this procedure:

  • does not require special rights (no root, no sudo)
  • assumes that you have a directory named $HOME/bin (if not, create it using the command mkdir $HOME/bin)

1. Make sure there is no command named ocamlc in your PATH variable


Execute, in a terminal window:

    type -p ocamlc

If there is no output, go on. If something is printer, then you need to set your PATH variable to a list of directories excluding the directory printed above. For instance:

    export PATH=$HOME/bin:/bin:/usr/bin


2. Fetch the binary for OPAM and install it in $HOME/bin


    wget -O - | sh -s $HOME/bin


If this does not work:

  1. find the correct binary at
  2. download it into $HOME/bin
  3. make it executable (chmod a+x)
  4. and rename (or link) it as opam

3. Then, initialize your OPAM environment and install the (for instance) 4.04.0 OCaml release


    $HOME/bin/opam init --comp=4.04.0

4. Install other OCaml packages


For instance:

    $HOME/bin/opam install merlin tuareg ocp-indent

5. Check your shell environment


OPAM has asked for the right to modify your shell startup file (typically .bashrc). Your .bashrc file should now contain something like:

    eval $(opam config env)

This is important: the OCaml commands are now located into $HOME/.opam/4.04.0/bin, and this directory should now occur in your PATH variable/.


To are now ready to use OCaml in a new shell terminal. Enjoy!



Author: Michel Mauny

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