3.6.     83

  Path  ,    -
  PATH.

 setenv ()      -
         .
 name    ,    
.    ,   
value.  ,   name,  ,  
  ,   value  ,  -
 overwrite   .    overwrite -
 0,      . 
setenv ()  0   ,      -
1.  unsetenv ()   ,   name.

3.6.4.   system () 
 

 system ()       -
.  system <)   fork (),     -
   ()  ,     .



#include <stdlib.h>

int system(const char *string);

   string       -
 .        
 ,   (  ).  -
    , ..     
 fork ()   ()      
    .

 system ()    .  
   ()   127,     -
   -1.         .

3.6.5.  POSIX-  


      system ()  fork-exec, -
 posix_spawn()        -
.   posix_spawn()     
 "" , ..     -
 ,    :

  ;

  ;

   ;