It looks like one of the scripts is running under
/bin/sh but uses extended features of bash, possibly
<(. You presumably have ash as
/bin/sh; that's legitimate (and ash is measurably faster and uses less memory than bash, which is why many distributions don't put bash as
/bin/sh), but occasionally you run into scripts that rely on bash yet start with
That you have
$SHELL set to bash is irrelevant, each script is executed by the shell indicated on the first line (the shebang, here
#!/bin/sh). I've had a quick look at the RVM scripts, and it looks like all the ones that rely on bash extensions correctly start with
#!/usr/bin/env bash. Do you have a prior existing
~/.rvm? If so, try moving it out of the way.
You can get an execution trace for a shell script by running the shell with the
-x option. So run
bash -x ./rvm and see where the error occurs. If the error occurs in a script called indirectly from the main
rvm script, try adding
set -x in the other scripts as well (immediately below the
#! line), to see an execution trace for them. This should help locate the offending script.