  643  vi t1.txt
  644  grep Thomas <t1.txt 
  645  grep Thomas <t1.txt >erg.txt
  646  cat erg.txt 
  647  clear
  648  greb Thomas <t1.txt >erg.txt
  649  greb Thomas <t1.txt >erg.txt 2>err.txt
  650  cat err.txt 
  651  greb Thomas <t1.txt >erg.txt 2>/dev/null 
  652  clear
  653  find / -name susi.txt 
  654  find / -name susi.txt 2>/dev/null
  655  clear
  656  find / -name susi.txt 2>err.txt
  657  rm err.txt 
  658  clear
  659  cat file1.txt 
  660  ls
  661  clear
  662  cat t1.txt 
  663  clea
  664  clear
  665  cat <t1.txt 
  666  cat <t1.txt | grep Thomas
  667  cat <t1.txt | grep Thomas | grep Hallo
  668  clear

