```1. linux2. bash 3. shell script3. tar4. gzip5. unzip6. fcrackzip7. password.txt``````#!/bin/bashx=1819while [ $x -gt -1  ]do  typ=`ls $x.*|cut -f2 -d.`  echo $x.$typ  case $typ in    gz)      out=`gzip -fkNd $x.$typ`      ;;    tar)      out=`tar -kxvf $x.$typ`      ;;    zip)      pas=`fcrackzip -Du $x.$typ -p password.txt|grep "=="|cut -f3 -d= |tr -d ' \n'`      #echo $x.$typ:$pas      out=`unzip -oP $pas $x.$typ`      ;;  esac  x=$(( $x - 1 ))done``````$ time bash loop.sh; more flag.txt1819.gz1818.tar1817.tar1816.gz1815.zip1814.tar......6.zip5.zip4.zip3.zip2.zip1.tar0.gz
real    0m17.057suser    0m13.506ssys     0m5.277srtcp{z1pPeD_4_c0uPl3_t00_M4Ny_t1m3s_a1b8c687}```