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 ULTRIX
shmat
shmop(2) System Calls Manual shmop(2)Name
shmop, shmat, shmdt - shared memory operations
Syntax
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
char *shmat (shmid, shmaddr, shmflg)
int shmid;
char *shmaddr;
int shmflg;
int shmdt (shmaddr)
char *shmaddr;
Description
The system call attaches the shared memory segment associated with the shared memory identifier specified by shmid to the data segment of
the calling process. The segment is attached at the address specified by one of the following criteria:
If shmaddr is equal to zero, the segment is attached at the first available address as selected by the system.
If shmaddr is not equal to zero and (shmflg & SHM_RND ) is true, the segment is attached at the address given by (shmaddr- (shmaddr modulus
SHMLBA )).
If shmaddr is not equal to zero and (shmflg & SHM_RND ) is false, the segment is attached at the address given by shmaddr.
The segment is attached for reading if (shmflg & SHM_RDONLY ) is true. Otherwise, it is attached for reading and writing.
The system call detaches from the calling process's data segment the shared memory segment located at the address specified by shmaddr.
Return Values
Upon successful completion, the return values are as follows:
o The system call returns the data segment start address of the attached shared memory segment.
o The system call returns a value of zero (0).
Otherwise, a value of -1 is returned, and errno is set to indicate the error.
Diagnostics
The system call fails and not attach the shared memory segment, if any of the following is true:
[EINVAL] The shmid is not a valid shared memory identifier.
[EACCES] Operation permission is denied to the calling process. For further information, see
[ENOMEM] The available data space is not large enough to accommodate the shared memory segment.
[EINVAL] The shmaddr is not equal to zero, and the value of (shmaddr- (shmaddr modulus SHMLBA )) is an illegal address.
[EINVAL] The shmaddr is not equal to zero, (shmflg & SHM_RND ) is false, and the value of shmaddr is an illegal address.
[EMFILE] The number of shared memory segments attached to the calling process would exceed the system imposed limit.
The fails and does not detach the shared memory segment if:
[EINVAL] The shmaddr is not the data segment start address of a shared memory segment.
See Alsoexecve(2), exit(2), fork(2), shmctl(2), shmget(2)shmop(2)