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  • If I run random=$(bash -c "RANDOM=640; echo $RANDOM") shouldn't it return the same each time? Or is it because the $(bash ... isn't treated as a new instance of bash? Commented Nov 17, 2017 at 17:47
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    doublequotes is probably not what you want there Commented Nov 17, 2017 at 17:55
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    Watch what happens if you do: set -x; FOO=42; bash -c "FOO=999; echo $FOO". The double-quotes are allowing the outer shell to replace $RANDOM with the outer shell's random; the inner bash shell is simply echoing an integer. Commented Nov 17, 2017 at 17:56
  • @thrig I need double quotes because in my case it is actually random=$(bash -c "RANDOM=$mac; echo $RANDOM") Commented Nov 17, 2017 at 17:56
  • Of course it should be bash -c 'RANDOM=42; echo "$RANDOM" "$RANDOM" "$RANDOM"'. Commented Nov 18, 2017 at 0:58