$echo $
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$BASH_ALIASES $HISTFILE $OSTYPE
$BASH_ARGC $HISTFILESIZE $PATH
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$BASH_COMMAND $HOSTNAME $PS1
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$BASH_COMPLETION_COMPAT_DIR $i $PS4
$BASH_COMPLETION_DIR $IFS $PWD
$BASH_LINENO $L3_HOME $RANDOM
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