  mtab.     
  ,       .
       
/proc/mounts    cat.    mtab   
   ,    
  /etc/mtab    /proc/mounts ( -
   ).      
"mount:   "    .

/etc/netgroup.   ,     
          -
  .

/etc/nsswitch.conf. ,       NIS,
DNS,      ,     (. 
"nsswitch.conf:    "  11).

/etc/pam.d.       , 
  (.  ""  11).

     .     
 /etc/pam.d,    ,   .   -
      .

/etc/passwd.    .     ,
      ,    "-
     "  16.   
passwd     ,   
 :

_:_: _: _:::

_     ,   ,    
 login:     .  -
     . /  -
   /etc/ shadow (. ).      
  .        
  (*).

_   ,  0  , 
 1-499     . _ -
    .   ,   0-499 -
    ; .  /etc/group.   -
        /etc/login.defs.
  ,     -
  ,     .
  ,   ,    .  
   GECOS (. ).

       ,  
,      .   
,  /bin/bash.    /bin/tcsh    
Shell  /bin/zsh     Z Shell.    
chsh (.  " Linux"  11).

452                                       IV.  