fedora 9如何开启对mandatory locking的支持?

camperbird

书上说只要文件权限里有l就可以,rwxr-lr--,这样就可以了,我chmod g+s,g-x以后没有开启,很显然l位在linux里是S,不知道怎么才能开启.

timespace

Mandatory locking

(Non-POSIX.) The above record locks may be either advisory or mandatory, and are advisory by default.

Advisory locks are not enforced and are useful only between cooperating processes.

Mandatory locks are enforced for all processes. If a process tries to perform an incompatible access (e.g., read(2) or write(2)) on a file region that has an incompatible mandatory lock, then the result depends upon whether the O_NONBLOCK flag is enabled for its open file description. If the O_NONBLOCK flag is not enabled, then system call is blocked until the lock is removed or converted to a mode that is compatible with the access. If the O_NONBLOCK flag is enabled, then the system call fails with the error EAGAIN or EWOULDBLOCK.

To make use of mandatory locks, mandatory locking must be enabled both on the file system that contains the file to be locked, and on the file itself. Mandatory locking is enabled on a file system using the "-o mand" option to mount(, or the MS_MANDLOCK flag for mount(2). Mandatory locking is enabled on a file by disabling group execute permission on the file and enabling the set-group-ID permission bit (see chmod(1) and chmod(2)).

camperbird

我再也不问这样的sb问题了,图个省事不自己去查man 手册