I saw this question and attempted to test the same but unfortunately couldn't get it to work with either a zip or gz. my js ended up looking like:
var cmdStr="unzip -j /folder/folder/folder/tester.zip -d folder/folder/folder";
i also read elsewhere that decompressing a file is possible in the data loading activity, by choosing 'pre-process the file' then inputting gunzip -c <%= vars.sourceFile %>
again couldn't get this to work
lastly i tried gunzip in a js activity, code was like:
execCommand('cd /folder/folder/folder \n gunzip "tester.csv.gz" ');
but again couldn't get it to work. am sure i am doing something basic wrong but error message just says error while evaluating so not sure what.
turns out it was just an issue with our configuration that prevented me seeing the decompress/decrypt dropdown on the data loading activity - all sorted now
script looks fine.
Can you check if you are authorized to run execCommand on ACC?