[Linux]O_CLOEXEC 标志

http://stackoverflow.com/questions/1315382/closing-all-open-files-in-a-process

If your program will be calling

fork

and

exec

, you really should open all file descriptors with the

O_CLOEXEC

flag so you don't have to manually close them before

exec

. You can also use

fcntl

to add this flag after a file is opened, but that's subject to race conditions in multithreaded programs.