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# tail perl -ne '$i=$.%5; $a[$i]=$_; END{print @a[$i+1..$#a,0..$i]}' file ... perl -pe '$a[$i=$.%5]=$_}{print@a[$i+1..@a,0..$i]' file perl -pe '$_[$==$.%5]=$_}{print@_[$=+1..@_,0..$=]' file
echo foo | perl -wpe 'your code here' file