ACCUMULO_JAVA_PREFIX in accumulo shell script not expanding correctly

[dlmarion]

The * subscript in ACCUMULO_JAVA_PREFIX at

accumulo/assemble/bin/accumulo

Line 86 in 38c261d

JAVA=("${ACCUMULO_JAVA_PREFIX[*]}" "$JAVA")

is expanding the array to a single word separated by IFS. In testing, I believe @ should be used here instead.

Versions (OS, Maven, Java, and others, as appropriate):

• Affected version(s) of this project: 2.10

To Reproduce
I wrote a script to test this out. The following fails:

ACCUMULO_JAVA_PREFIX=(
        '/usr/bin/numactl'
        '--all'
)

CMD=("${ACCUMULO_JAVA_PREFIX[*]}" "/usr/bin/java")

echo "${CMD[@]}"
exec "${CMD[@]}" "--version"

Changing * to @ on the line starting with CMD= allows the script to succeed.

[ctubbsii]

This may be intended. It is hard for me to remember exactly the reason for making this a scalar, but I think it's related to the fact that it's not possible to export an array in bash.

The workaround (and perhaps the intended behavior) is for the user to write their own prefix command that incorporates all the flags and options they need, and executes with "$@".

So, for example, instead of doing ACCUMULO_JAVA_PREFIX="numactl --all", you could instead do ACCUMULO_JAVA_PREFIX="mynumactl.sh" and the contents of mynumactl.sh would be numactl --all "$@".

[ctubbsii]

I will continue to look into this to see if there's something we should do to change this, so you can use an array. But there are trade-offs here that make no option perfect. If we use an array, you can't export it, and if you unintentionally set a scalar when we expect an array, we might not parse it correctly. If we expect a scalar and split it on IFS, then that could be a huge problem for quoting, requiring a bunch of convoluted quoting escapes, and assumptions about how the args are flattened when our script uses the environment variable. There's a good chance that the best option is to leave it as-is, and interpret it as a single scalar, requiring users to put multiple arguments into a script as suggested above.

[ctubbsii]

As it turns out, you can jump through hoops to effectively export an array variable, but it's not pretty (note: this still won't work without the patch in #3701, and the workaround above is still needed. I only mention this here because it provides a means to demonstrate that users can do some wild things and set these variables to things we don't expect, so we want to try to take that into account):

BASH_ENV=<(echo "declare -a ACCUMULO_JAVA_PREFIX='(numactl --all)'") bin/accumulo

If you set the variable as an array in the environment, but then try to set it as a scalar in the script, then the scalar will only override the first item in the array. This can result in some confusing behavior. I added a sensible check with declare -p in my PR #3701 to fix this.