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    The following form allows you to view linux man pages.

    Command:

    ftrylockfile

    
    
    

    SYNOPSIS

           #include <stdio.h>
    
           void flockfile(FILE *filehandle);
           int ftrylockfile(FILE *filehandle);
           void funlockfile(FILE *filehandle);
    
       Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
    
           All functions shown above:
               _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE ||
               _SVID_SOURCE || _POSIX_SOURCE
    
    
    

    DESCRIPTION

           The stdio functions are thread-safe.  This is achieved by assigning  to
           each  FILE object a lockcount and (if the lockcount is nonzero) an own-
           ing thread.  For each library call, these functions wait until the FILE
           object  is no longer locked by a different thread, then lock it, do the
           requested I/O, and unlock the object again.
    
           (Note: this locking has nothing to do with the  file  locking  done  by
           functions like flock(2) and lockf(3).)
    
           All this is invisible to the C-programmer, but there may be two reasons
           to wish for more detailed control.  On the one hand, maybe a series  of
           I/O  actions  by  one thread belongs together, and should not be inter-
           rupted by the I/O of some other thread.  On the other hand,  maybe  the
           locking overhead should be avoided for greater efficiency.
    
           To  this end, a thread can explicitly lock the FILE object, then do its
           series of I/O actions, then unlock.  This prevents other  threads  from
           coming in between.  If the reason for doing this was to achieve greater
           efficiency, one does the I/O with the nonlocking versions of the  stdio
           functions:   with  getc_unlocked(3)  and  putc_unlocked(3)  instead  of
           getc(3) and putc(3).
    
           The flockfile() function waits for *filehandle to be no  longer  locked
           by a different thread, then makes the current thread owner of *filehan-
           dle, and increments the lockcount.
    
           The funlockfile() function decrements the lock count.
    
           The ftrylockfile() function is a nonblocking  version  of  flockfile().
           It  does  nothing  in  case  some other thread owns *filehandle, and it
           obtains ownership and increments the lockcount otherwise.
    
    
    

    RETURN VALUE

           The ftrylockfile() function returns zero  for  success  (the  lock  was
           obtained), and nonzero for failure.
    
    
    

    ERRORS

           None.
    
    
    

    SEE ALSO

           unlocked_stdio(3)
    
                                      2013-07-23                      FLOCKFILE(3)
    
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