10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Trying to figure out a load issue with a webserver. I have traced a php script and noticed the following
connect(4, {sa_family=AF_INET, sin_port=htons(3306), sin_addr=inet_addr("XX.XX.XX.XX")}, 16) = -1 EINPROGRESS (Operation now in progress) <0.000035>
poll(, 1, 2000) = 1 () <0.000120>... (5 Replies)
Discussion started by: rajan007
5 Replies
2. AIX
while i try to start the audit i have the below error message .
audit>audit start
** auditing enabled already
A system call received a parameter that is not valid.
please advice (6 Replies)
Discussion started by: thecobra151
6 Replies
3. Programming
hi all,
i tried the following source codes:
fork1.c:
main()
{
printf("demo of fork\n");
fork();
printf("hello");
}
output:
demo of fork
hello hello
fork2.c:
main() (3 Replies)
Discussion started by: pnirmala
3 Replies
4. Programming
I have a cgi script which is called after certain time interval, which has this:
system ("ls -l /tmp/cgic* | grep -v \"cgicsave.env\" | awk '{print $5}'");
During the execution of this script,the output is 0 sometimes. But due to this the system call is not working at all and doesnt o/p... (2 Replies)
Discussion started by: xs2punit
2 Replies
5. UNIX for Advanced & Expert Users
Dear All,
I am having problem with read() system call in Blocking Mode.
In my driver interrupt intimation done through RT FIFO. so i have created the RT FIFO and open the FIFO using open() system call with O_RDONLY flag and i am waiting for interrupt using read() blocking call.initally... (1 Reply)
Discussion started by: rajamohan
1 Replies
6. Programming
Hi,
I am having an issue with using sockets.
I have a program which binds to a socket and listen on it. Later I spawn a thread to handle some function. In the new thread created I need to call a shell script which executes the specified function. Here I am using a system command to call the... (5 Replies)
Discussion started by: Janardhanbr
5 Replies
7. Linux
hi,
where can I find the detail information about the syscall in binary instructions of linux/mips.
for example, in linux/mips:
li v0, 4140
syscall
it's a syacall of "lseek" , but how can I find that which registers will be used in this syscall , and the meaning of the arguments in the... (2 Replies)
Discussion started by: zerocool_08
2 Replies
8. Programming
Hi,
I have a daq program that runs in an infinite loop until it receives SIGINT. A handler catches the signal and sets a flag to stop the while loop. After the loop some things have to be cleaned up.
The problem is that I want my main while loop to wait until the next full second begins, to... (2 Replies)
Discussion started by: soeckel
2 Replies
9. UNIX for Advanced & Expert Users
Hi,
Ho do I differentiate system call from library call?
for example if I am using chmod , how do I find out if it is a system call or library call?
Thanks
Muru (2 Replies)
Discussion started by: muru
2 Replies
10. Programming
Dear Friends,
I write a c program to list the directories recursively. For this I write a function called my_readdir to read the content of directory. For this I use read system call it returns -1, then I use readdir system call it gives comment terminated error or segmentation... (1 Reply)
Discussion started by: spmlingam
1 Replies
MSGCTL(2) BSD System Calls Manual MSGCTL(2)
NAME
msgctl -- message control operations
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/msg.h>
int
msgctl(int msqid, int cmd, struct msqid_ds *buf);
DESCRIPTION
The msgctl() system call performs control operations on the message queue specified by msqid.
Each message queue has a msqid_ds structure associated with it which contains the following members:
struct ipc_perm msg_perm; /* msg queue permission bits */
msgqnum_t msg_qnum; /* # of msgs in the queue */
msglen_t msg_qbytes; /* max # of bytes on the queue */
pid_t msg_lspid; /* pid of last msgsnd() */
pid_t msg_lrpid; /* pid of last msgrcv() */
time_t msg_stime; /* time of last msgsnd() */
time_t msg_rtime; /* time of last msgrcv() */
time_t msg_ctime; /* time of last msgctl() */
The ipc_perm structure used inside the msgid_ds structure is defined in <sys/ipc.h> and contains the following members:
uid_t cuid; /* creator user id */
gid_t cgid; /* creator group id */
uid_t uid; /* user id */
gid_t gid; /* group id */
mode_t mode; /* permission (lower 9 bits) */
The operation to be performed by msgctl() is specified in cmd and is one of:
IPC_STAT Gather information about the message queue and place it in the structure pointed to by buf.
IPC_SET Set the value of the msg_perm.uid, msg_perm.gid, msg_perm.mode and msg_qbytes fields in the structure associated with msqid. The
values are taken from the corresponding fields in the structure pointed to by buf. This operation can only be executed by the
super-user, or a process that has an effective user id equal to either msg_perm.cuid or msg_perm.uid in the data structure associ-
ated with the message queue. The value of msg_qbytes can only be increased by the super-user. Values for msg_qbytes that exceed
the system limit (MSGMNB from <sys/msg.h>) are silently truncated to that limit.
IPC_RMID Remove the message queue specified by msqid and destroy the data associated with it. Only the super-user or a process with an
effective uid equal to the msg_perm.cuid or msg_perm.uid values in the data structure associated with the queue can do this.
The permission to read from or write to a message queue (see msgsnd(2) and msgrcv(2)) is determined by the msg_perm.mode field in the same
way as is done with files (see chmod(2)), but the effective uid can match either the msg_perm.cuid field or the msg_perm.uid field, and the
effective gid can match either msg_perm.cgid or msg_perm.gid.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.
ERRORS
msgctl() will fail if:
[EPERM] cmd is equal to IPC_SET or IPC_RMID and the caller is not the super-user, nor does the effective uid match either the
msg_perm.uid or msg_perm.cuid fields of the data structure associated with the message queue.
An attempt was made to increase the value of msg_qbytes through IPC_SET, but the caller is not the super-user.
[EACCES] cmd is IPC_STAT and the caller has no read permission for this message queue.
[EINVAL] msqid is not a valid message queue identifier.
cmd is not a valid command.
[EFAULT] buf specifies an invalid address.
SEE ALSO
msgget(2), msgrcv(2), msgsnd(2)
STANDARDS
The msgctl system call conforms to X/Open System Interfaces and Headers Issue 5 (``XSH5'').
HISTORY
Message queues appeared in the first release of AT&T System V UNIX.
BSD
August 25, 1999 BSD