shm_open() vs. shmget(); shm_open() vs. open()
Alex Vinokur
1. shm_open() vs. shmget()
int fd = shm_open(...);
We can't see that shared memory segment via icps.
How can we see all shared memory segments created via shm_open?
2. shm_open() vs. open()
int fd1 = shm_open(...);
int fd2 = open();
What can we do via fd1 but can't do via fd2?
Alex
Zeljko Vrba
> Hi,
>
> 1. shm_open() vs. shmget()
>
> int fd = shm_open(...);
>
> We can't see that shared memory segment via icps.
>
> How can we see all shared memory segments created via shm_open?
>
(SHM segments, message queues and semaphores).
>
> 2. shm_open() vs. open()
>
> int fd1 = shm_open(...);
> int fd2 = open();
>
> What can we do via fd1 but can't do via fd2?
>
I don't know.
WANG Cong
> Hi,
>
> 1. shm_open() vs. shmget()
>
> int fd = shm_open(...);
>
> We can't see that shared memory segment via icps.
You must mean 'ipcs'.
>
> How can we see all shared memory segments created via shm_open?
>
No way, because the sem you created via shm_open() is based
on files, no memory. Thus you can't see any related memory
segments.
>
> 2. shm_open() vs. open()
>
> int fd1 = shm_open(...);
> int fd2 = open();
>
> What can we do via fd1 but can't do via fd2?
Almost nothing, IMO.
In fact on Linux shm_open() are implemented as tmpfs files,
nothing particular than other regular files.
--
Live like a child, think like the god.
Maxim Yegorushkin
> Hi,
>
> 1. shm_open() vs. shmget()
>
> int fd = shm_open(...);
>
> We can't see that shared memory segment via icps.
>
> How can we see all shared memory segments created via shm_open?
On Linux you can `ls -l /dev/shm`, provided tmpfs is used.
--
Max