Linux Network Programming-file attributes fcntl Function

Linux Network Programming-file attributes fcntl Function

/* Use the fcntl control file operator */# include
  
   
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Int main (void) {int flags =-1; int accmode =-1;/* Get the status of the standard input */flags = fcntl (0, F_GETFL, 0 ); if (flags <0) {/* error occurs */printf ("failure to use fcntl \ n"); return-1 ;} /* obtain access mode */accmode = flags & O_ACCMODE; if (accmode = O_RDONLY)/* READ-ONLY */printf ("stdin read only \ n "); else if (accmode = O_WRONLY)/* write only */printf ("stdin write only \ n"); else if (accmode = O_RDWR) /* readable/printf ("stdin read write \ n"); else/* Other MODE */printf ("stdin unknown mode"); if (flags & O_APPEND) printf ("stdin append \ n"); if (flags & O_NONBLOCK) printf ("stdin nonblock \ n"); return 0 ;}
    
   
  

Example 1: Use the int fcntl (int fd, int cmd) function. The returned value is the new file descriptor/* use fcntl to modify the File status value */# include  # Include  # Include  # Include  /* Strlen function */# define NEWFD 8int main (void) {char buf [] = "FCNTL"; int fd = open ("test.txt", O_RDWR ); printf ("the file test.txt ID is % d \ n", fd);/* get the file status */fd = fcntl (fd, F_GETFD ); printf ("the file test.txt ID is % d \ n", fd); fd = NEWFD;/* write status to */fcntl (NEWFD, F_SETFL, & fd ); /* write the string */write (NEWFD, buf, strlen (buf); close (NEWFD); return 0 ;}example 2: use the int fcntl (int fd, int cmd, long arg) function; return value is the obtained response flag/* use fcntl to modify the File status value */# include  # Include  # Include  # Include  /* Strlen function */int main (void) {int flags =-1; char buf [] = "FCNTL"; int fd = open ("test.txt", O_RDWR ); /* get the file status */flags = fcntl (fd, F_GETFL, 0);/* increase the status to append */flags | = O_APPEND; /* write status to */flags = fcntl (fd, F_SETFL, & flags); if (flags <0) {/* error occurred */printf ("failure to use fcntl \ n"); return-1;}/* write the string */write (fd, buf, strlen (buf); close (fd); return 0 ;}        

<喎?http: www.bkjia.com kf ware vc " target="_blank" class="keylink"> VcD4NCjxwcmUgY2xhc3M9 "brush: java;"> /* Use fcntl to obtain the process ID for receiving signals */# include # Include # Include # Define NEWFD 8int main (void) {int uid;/* open the file test.txt */int fd = open ("test.txt", O_RDWR ); /* process ID for receiving signals */uid = fcntl (fd, F_GETOWN); printf ("the SIG recv ID is % d \ n", uid ); close (fd); return 0 ;}

/* Use fcntl to set the process ID for receiving signals: 1000 */# include  # Include  # Include  # Define NEWFD 8int main (void) {int uid;/* open the file test.txt */int fd = open ("test.txt", O_RDWR ); /* process ID for receiving signals */uid = fcntl (fd, F_SETOWN, 1000); close (fd); return 0 ;}