Shell Programming and Scripting

    
  elm,mail
  elm,lisp,composer,cd,ls,cd,ls,cd,ls,zcat,|,tar,-xvf,ls,cd,ls,cd,ls,vi,ls,cd,ls,vi,elm,-f,ls,rm,ls,cd,ls,vi,vi,ls,vi,ls,cd,ls,elm,cd,ls,cd,ls,vi,vi,vi,ls,vi,ls,i,vi,ls,cp,cd,fg,ls,rm,cd,ls,-l,exit
  elm,mail,biff,elm,biff,elm,elm
  elm,ls
  elm,grep,mail,man,man,-k,fg,look,fg,elm,finger,elm,finger,cd,ls,cd,cd,ls,cd,ls,cd,ls,-l,date,more,ls,-l,more,ls,more,ls,rm,ls,cd,ls,mail,elm,look,fg,fg,cd,cd,ls,cd,ls,cd,ls,cd,ls,vi,man,ls,cd,cd,ls,vi,echo,man,-k,man,ls,cd,ls,biff,ls,elm,fg,exit
  elm,biff,biff,mail,elm,date,rlogin,-l,fg,elm,ls,biff,elm,mesg,finger,finger,talk,logout
  elm,ls,finger,finger,|,more,biff,matlab,clear,elm,rn,ls,matlab,mail,fg,elm,ls,exit
  elm,fk
  matlab
  elm,finger,finger,elm
  cd,ls,cd,ls,ls,-l,sccs,vi,vi,vi,vi,sccs,clear,fg,vi,sccs,ls,ls,-l,vi,vi,vi,vi,clear,sccs,vi,sccs,exit
  elm,mail,exit
  elm,fk,date,mail,exit

cat workeditf.txt | awk -F"," '{if (NF = 3) print }' > 1.txt

  elm mail 
  elm lisp composer
  elm mail biff
  elm ls 
  elm grep mail
  elm biff biff
  elm ls finger
  elm fk 
  matlab  
  elm finger finger
  cd ls cd
  elm mail exit
  elm fk date

  
  elm mail exit

grep '^[^,]*,[^,]*,[^,]*$' a.txt