popd:    

      
 popd ("pop directory"   ).  -
  . 9.5,  popd     -
         -
  :

$ popd

~/demo '/names
$ pwd
/home/scott/demo

. 9.5.  
    
  popd

  ,     
,   popd   , -
    :

$ popd +1

-/demo
$ pwd

/home/scott/demo

     ,      0, 
  .



 (process)      Linux. , -
    ,  ,  ,     .
    Linux      .  -
       ,    -
    .     
       ,  -
  .   ,      -
    ,  cd.

 

   ,    :  -
,     (root).   3 (fork) 
, ,   ,    .  -
    (spawn);    ( 
 fork  spawn  . .)     -
  (system call)    ,  fork.   -
 ,   Linux        -
    (spontaneous process) init  PID,  1. 

3  fork ("") ,  , ,     
,     .     ,  -
 ,    ,     .

296  III.   Red Hat Linux

