fork in freeBSD unix
答
http://svn.freebsd.org/base/release/7.1.0/sys/kern/kern_fork.c
DESCRIPTION
The fork() system call causes creation of a new process. The new process
(child process) is an exact copy of the calling process (parent process)
except for the following:
+o The child process has a unique process ID.
+o The child process has a different parent process ID (i.e., the
process ID of the parent process).
+o The child process has its own copy of the parent's descriptors.
These descriptors reference the same underlying objects, so
that, for instance, file pointers in file objects are shared
between the child and the parent, so that an lseek(2) on a
descriptor in the child process can affect a subsequent read(2)
or write(2) by the parent. This descriptor copying is also
used by the shell to establish standard input and output for
newly created processes as well as to set up pipes.
+o The child process' resource utilizations are set to 0; see
setrlimit(2).
+o All interval timers are cleared; see setitimer(2).
但为什么在子进程效果父一个lseek的process.Does'nt像每个进程打开的文件中当前指针中的信息保持在用户结构,其两者不同? 谢谢 – mawia 2009-04-19 06:49:57