Cannot run /bin/mpirun

[cbordage]

When I run /bin/mpirun, I get the following error

A prefix was supplied to mpirun that only contained slashes.

But if I run mpirun, it works.

On my distribution (archlinux), which mpirun returns /bin/mpirun (/bin is a symbolic link to /usr/bin).

[jsquyres]

What version of Open MPI are you using?

[bgoglin]

He was using 3.1.1 but the relevant code seemed identical in master.

[jsquyres]

This is likely a simple string parsing problem. Any chance you can look into it?

[rhc54]

When you specify a full path to mpirun, OMPI considers that as equivalent to passing --prefix on the cmd line. Probably an issue of parsing that option incorrectly - it isn't used or tested much.

[jsquyres]

FWIW, I use /path/to/mpirun all the time. 😁

But there's probably some corner case in the string parsing that isn't handled properly (e.g., in the case of /bin/mpirun, the prefix is just /, which is what mpirun is nominally complaining about).

[ggouaillardet]

/bin is always trimmed from the end of the prefix.

For example /usr/bin/mpirun -> prefix is /usr

In this case, /bin/mpirun -> prefix is / -> abort.

@jsquyres @rhc54 @bosilca @hjelmn any recollection on why we abort when the prefix is / ?

If mpirun is in /bin/mpirun, what should be the prefix ? / (and no abort) ? /bin ? something else ?

[rhc54]

I think the prefix would have to be / and we shouldn't abort. This assumes that the libraries will be under /lib or /lib64 etc. I'm not sure what to do if they were put somewhere else - in this case, there is a symlink used to point at the real location in /usr, so it is possible the corresponding symlinksfor libraries wasn't made. Suspect we'd just have to declare that a busted environment.

[jsquyres]

Yeah, I'm not really sure why we have that error (i.e., that there's a prefix that is only /). That might just be over-zealous...?

[AntoineMazuyer]

Hi all,

I also have the same issue using Manjaro (arch based) distribution. I am not sure a busted environment is to blame.

[lahwaacz]

The /bin -> /usr/bin symlink in Arch provides compatibility for things which hardcode paths through /bin. The which tool is not such thing - if which mpirun produces /bin/mpirun, it's because you have /bin in your $PATH. If you remove it, then which mpirun produces /usr/bin/mpirun. Also note that the default $PATH in Arch is just /usr/local/sbin:/usr/local/bin:/usr/bin.