I can kind of explain it, perlvar says
The process number of the Perl running this script. You should consider this variable read-only, although it will be altered across fork() calls. (Mnemonic: same as shells.)
When you do, ``, you're doing a fork. If you do it twice in one statement (as in perl -Tle"`dir $$`, `dir $$`"), $$ will be tainted after the first fork.

update: well, if any variable triggers this then it may very well be a bug. perl -Tle"$a=1;`dir $a`, `dir $a`" Though there is always do ;) perl -Tle"$a=1;`dir $a`, do{`dir $a`}"

update: yeah, i was reachin' with the fork theory :)(and, btw, i couldn't find a perlbug report on this)

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In reply to Re: Taint bug with backticks in variable assignments by PodMaster
in thread Taint bug with backticks in variable assignments by shotgunefx

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