I have installed an application that runs correctly for root but not other users. The application generates an error that indicates users don't have permission to attach to shared memory. A daemon process creates the shared memory segment. I've checked every permission I can think of but nothing... (2 Replies)
Hi,
I'm developing a data processing pipeline with multiple stages, with data being moved between the stages using shared memory segments. The size of the data is typically of the order of hundreds of megabytes, and there are typically a few tens of main shared memory segments each of size... (2 Replies)
1) when user login to the server the session got colosed. How will resolve?
2) While firing the command ls -l we are not able to see the any files in the director. but over all view the file system using the command df -g it is showing 91% used. what will be the problem?
Thanks in advance. (1 Reply)
I have a process that need two active connections to the same zone of shared memory. But when i do the second call to shmat it give me error 22 (EINVAL). Only works ok the second call to shmat if i disconnect the first connection (shmdt)
In Sun,AIX and Digital, i donīt have this problem.
... (7 Replies)
I have a process that needs two active connections to the same zone of shared memory simultaneously.
The firs conection works ok, but when i do the second call to shmat it give me error 22 (EINVAL). Only works ok the second call to shmat if i disconnect the first connection (shmdt)
Steps:... (3 Replies)
Hi,
I'm using Ubuntu 10.04 on a 64bit machine.
In my shmat() call, I want to assign fixed memory address to shmaddr variable. I have no idea which address value to give. Some where in the net I read we can make use of sysproc info to know the user space addresses, but could not figure out how... (1 Reply)
Hi,
My program was running for a whole night. after 12 hours i got an error message "Cannot allocate memory" during the shmat commmand. So can you please let me know what could be the reason? is there any solution?
thanks in advance.
Regards,
Mano (5 Replies)
Hi,
This is rather a question from a "user" than from a sys admin, but I think this forum is apropriate for the question.
I have an adress with automatic email forwarding and for some senders (two hietherto), emails are bouncing. This has really created a lot of problems those two time so I... (0 Replies)
I don't know if you guys get this problem sometimes at Terminal but I had been having this problem since yesterday :( Maybe I overdid the Terminal. Even the codes that used to work doesn't work anymore.
Here is what 's happening:
* I wanted to remove lines containing digits so I used this... (25 Replies)
Discussion started by: Nexeu
25 Replies
LEARN ABOUT MOJAVE
shmat
SHMAT(2) BSD System Calls Manual SHMAT(2)NAME
shmat, shmdt -- map/unmap shared memory
SYNOPSIS
#include <sys/shm.h>
void *
shmat(int shmid, const void *shmaddr, int shmflg);
int
shmdt(const void *shmaddr);
DESCRIPTION
shmat() maps the shared memory segment associated with the shared memory identifier shmid into the address space of the calling process. The
address at which the segment is mapped is determined by the shmaddr parameter. If it is equal to 0, the system will pick an address itself.
Otherwise, an attempt is made to map the shared memory segment at the address shmaddr specifies. If SHM_RND is set in shmflg, the system will
round the address down to a multiple of SHMLBA bytes (SHMLBA is defined in <sys/shm.h> ). A shared memory segment can be mapped read-only by
specifying the SHM_RDONLY flag in shmflg. shmdt() unmaps the shared memory segment that is currently mapped at shmaddr from the calling
process' address space. shmaddr must be a value returned by a prior shmat() call. A shared memory segment will remain existant until it is
removed by a call to shmctl(2) with the IPC_RMID command.
RETURN VALUES
shmat() returns the address at which the shared memory segment has been mapped into the calling process' address space when successful,
shmdt() returns 0 on successful completion. Otherwise, a value of -1 is returned, and the global variable errno is set to indicate the error.
ERRORS
The shmat() system call will fail if:
[EACCES] The calling process has no permission to access this shared memory segment.
[EINVAL] shmid is not a valid shared memory identifier. shmaddr specifies an illegal address.
[EMFILE] The number of shared memory segments has reached the system-wide limit.
[ENOMEM] There is not enough available data space for the calling process to map the shared memory segment.
The shmdt() system call will fail if:
[EINVAL] shmaddr is not the start address of a mapped shared memory segment.
LEGACY SYNOPSIS
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
The include files <sys/types.h> and <sys/ipc.h> are necessary for both functions.
SEE ALSO mmap(2), shmctl(2), shmget(2), compat(5)BSD August 17, 1995 BSD