How to make dune run in crontab?

Learning
1

There’s a simple demo project js101,

bin/dune:

(executable
 (name main)
 (modes js)
 (preprocess (pps js_of_ocaml-ppx))
 (libraries js_of_ocaml js_of_ocaml-ppx))

bin/main.ml:

open Js_of_ocaml

let () =
  let console = Js.Unsafe.pure_js_expr "console" in
  let log_func = Js.Unsafe.get console "log" in
  let message = Js.string "Hello, JavaScript!" in
  Js.Unsafe.fun_call log_func [| Js.Unsafe.inject message |]

For some reason, we need to run it in crontab, so here’s the testjs.sh:

rm -rf /home/ubuntu/todel/js101/_build/;
cd /home/ubuntu/todel/js101/;
dune build;
cp /home/ubuntu/todel/js101/_build/default/bin/main.bc.js /home/ubuntu/todel/;
echo "done";

Here’s the crontab:

*/5 * * * * sh /home/ubuntu/todel/testjs.sh >> /home/ubuntu/todel/testjs.log

It seems that the script been triggered success with:

$ cat testjs.log 
done
done

However, there no main.bc.js file generated by the crontab.

~/todel$ ls
js101  testjs.log  testjs.sh

But when I run the script from terminal, it does there:

~/todel$ sh testjs.sh 
done                  

~/todel$ ls
js101  main.bc.js  testjs.log  testjs.sh
2

Maybe you forgot to load your opam env in your script?

Also I would use ˋset -eˋ and ˋset -x` to debug things further (though I’m not 100% sure if those are bash only switches)

3

You should also redirect stderr, otherwise you risk missing some error messages.

Cheers,
Nicolas

4

It seems that there’s some error with the so, the log shows:

+ export PATH=/home/ubuntu/.opam/ide-dev/bin:/usr/bin:/bin
+ export LD_LIBRARY_PATH=/home/ubuntu/.opam/ide-dev/lib/stublibs:
+ rm -rf /home/ubuntu/todel/js101/_build/
+ cd /home/ubuntu/todel/js101/
+ dune build
File "_none_", line 1:
Error: I/O error: dlljsoo_runtime_stubs.so: No such file or directory

I have set the LD_LIBRARY_PATH in the script:

set -e
set -x

export PATH="/home/ubuntu/.opam/ide-dev/bin:$PATH"
export LD_LIBRARY_PATH="/home/ubuntu/.opam/ide-dev/lib/stublibs:$LD_LIBRARY_PATH"

rm -rf /home/ubuntu/todel/js101/_build/;
cd /home/ubuntu/todel/js101/;
dune build;
cp /home/ubuntu/todel/js101/_build/default/bin/main.bc.js /home/ubuntu/todel/;
echo "done";

And the so exists:

$ ls -l /home/ubuntu/.opam/ide-dev/lib/stublibs/dlljsoo_runtime_stubs.so
-rwxr-xr-x 1 ubuntu ubuntu 56808 May 30 15:31 /home/ubuntu/.opam/ide-dev/lib/stublibs/dlljsoo_runtime_stubs.so

Update: It seems that we only need set CAML_LD_LIBRARY_PATH