which  whereis?   ,    ,  
which            -
.           ,
which      (   ).
 whereis         -
 .  whereis,     () ,
- man-     .

 which    (),     
. (     Linux     -
 6.)            . -
             -
.      ,    -
  which.     which  
 tar:

$ which tar

/bin/tar

 which  ,     ,  . -
 which,   ,       
,   . (     -
   "    "  6.) ,  tar -
  ,  ,   ,    /usr/local/bin/tar,
  /bin/tar,   ,    .

which, whereis   .     which,  whereis  -
      ,      -
 (,   , .  " "  7).
     whereis ,    echo (-
     ,     ),   -
 :

$ whereis echo

echo: /bin/echo /opt/../bin/echo /usr/man/manl/echo.l

 whereis     echo.   which 
 :

$ which echo

/bin/echo

 whereis     ,   -
  ,     . ,   -
   tar:

$ whereis tar

tar: /bin/tar /usr/include/tar.h /usr/share/man/manl/tar.l.gz

 whereis     tar.    man-  -
,    .     whereis   tar,  -
   man-.

172  II.   Red Hat Linux