$ Is
a.out       acctspay.c acctsrec.c ledger.

  . out     ,   -
   :      .   . 27.1
    ,      
a. out        :

$ ./a. out < mymerno

    a. out,        .
       :

$ mv a.out accounting

    . out,      
 .  -       -
  ,   a. out.      
accounting:

$ gcc - accounting ledger. acctspay.c acctsrec.c

  accounting   ,     -
  :

$ accounting

     ,    gcc  -.
 -  ,       ; 
        -
    .        -
  ,  gcc ,       -
.    gcc      :

$ gcc - ledger. acctspay.c acctsrec.c

$ Is
acctspay.c acctspay.o acctsrec.c acctsrec.o ledger.     ledger.

    gcc,      , gcc
  .      
 . ,  ,     .    
   .-,  .-,     :

$ gcc - accounting ledger. acctspay.c acctsrec.o

  ,  . -     -
,  . -  .        -
  ,   .,      ( 
  ).       -
 .

     ,     -
.        ,  -
  ,        .     -
         
 .       ,     -
,        .  -

 27.                                          829