pwd: /out/package
ppid: 504
   1: WRITELN echo 123 > 1.txt
   2: WRITELN echo 222 > 2.txt
   3: WRITELN echo 321 > 4.txt
   4: WRITELN cat<1.txt 2.txt>3.txt 4.txt
   5: WRITELN cat 1.txt
   6: WRITELN cat 2.txt
   7: WRITELN cat 3.txt
   8: WRITELN cat 4.txt
   9: WRITELN ls
  10: WRITELN exit