fcntl example
Setting the Close-on-Exec Flag. The following example demonstrates how to set the close-on-exec flag for the file descriptor fd. #include <unistd.h> #include <fcntl.h> ... int flags; flags = fcntl(fd, F_GETFD); if (flags == -1) /* Handle error, With this example we see the need for fcntl. Our program operates on a descriptor (standard output), never knowing name of the file that was opened by the shell on that descriptor. We can't set the O_SYNC flag when the file is opened, since the shell, The fcntl version has a major advantage: It works with files on NFS file systems (as long as the NFS server is reasonably recent and correctly configured). So, if you have access to two machines that both mount the same file system via NFS, you can repea,Several systems have more fields in struct flock such as, for example, l_sysid. Clearly, l_pid alone is not going to be very useful if the process holding the lock may live on a different machine. The original Linux fcntl() system call was not designed to, In fcntl.h or its documentation ( man fcntl ). For example, on my MacBook the man page says: The flags for the F_GETFL and F_SETFL commands are as follows: O_NONBLOCK Non-blocking I/O; if no data is available to a read call, or if a write operation would,lock.l_start = 0; lock.l_whence = SEEK_SET; lock.l_len = 0; savelock = lock; fcntl(fd, F_GETLK, &lock); /* Overwrites lock structure with preventors. */ if (lock.l_type == F_WRLCK) printf("Process %ld has a write lock already!-n", lock.l_pi,An example: >>> import array, fcntl, struct, termios, os >>> os.getpgrp() 13341 >>> struct.unpack('h', fcntl.ioctl(0, termios.TIOCGPGRP, " "))[0] 13341 >>> buf = array.array('h', [0]) >>&,fcntl() - Unix, Linux System Calls Manual Pages (Manpages) , Learning fundamentals of UNIX in simple and easy steps : A beginner's tutorial containing complete knowledge of Unix Korn and Bourne Shell and Programming, Utilities, File System, Directorie,The following example uses the flock function to place an advisory lock on the file, while it is being updated. The output shown below was obtained by running three instances of the program in parallel, like this: python fcntl-example-1.py& python fcn
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 fcntl example 相關參考資料
fcntl - The Open Group Library
Setting the Close-on-Exec Flag. The following example demonstrates how to set the close-on-exec flag for the file descriptor fd. #include <unistd.h> #include <fcntl.h> ... int flags; flags... http://pubs.opengroup.org fcntl Function | Advanced Programming in the UNIX® Environment ...
With this example we see the need for fcntl. Our program operates on a descriptor (standard output), never knowing name of the file that was opened by the shell on that descriptor. We can't set t... http://www.informit.com fcntl: Locks and Other File Operations | Linux System Calls | InformIT
The fcntl version has a major advantage: It works with files on NFS file systems (as long as the NFS server is reasonably recent and correctly configured). So, if you have access to two machines that... http://www.informit.com fcntl(2) - Linux manual page - man7.org
Several systems have more fields in struct flock such as, for example, l_sysid. Clearly, l_pid alone is not going to be very useful if the process holding the lock may live on a different machine. The... http://man7.org file io - c - Usage of F_GETFL and F_SETFL - Stack Overflow
In fcntl.h or its documentation ( man fcntl ). For example, on my MacBook the man page says: The flags for the F_GETFL and F_SETFL commands are as follows: O_NONBLOCK Non-blocking I/O; if no data is ... https://stackoverflow.com File Locking and Unlocking With Fcntl
lock.l_start = 0; lock.l_whence = SEEK_SET; lock.l_len = 0; savelock = lock; fcntl(fd, F_GETLK, &lock); /* Overwrites lock structure with preventors. */ if (lock.l_type == F_WRLCK) printf("P... http://voyager.deanza.edu 36.10. fcntl — The fcntl and ioctl system calls — Python 2.7.14 ...
An example: >>> import array, fcntl, struct, termios, os >>> os.getpgrp() 13341 >>> struct.unpack('h', fcntl.ioctl(0, termios.TIOCGPGRP, " "))[0] 13341 >... https://docs.python.org fcntl() - Unix, Linux System Call - TutorialsPoint
fcntl() - Unix, Linux System Calls Manual Pages (Manpages) , Learning fundamentals of UNIX in simple and easy steps : A beginner's tutorial containing complete knowledge of Unix Korn and Bourne Sh... http://www.tutorialspoint.com The fcntl module - effbot.org
The following example uses the flock function to place an advisory lock on the file, while it is being updated. The output shown below was obtained by running three instances of the program in paralle... http://effbot.org |