Just to update, i found a easier solution to this problem.
Intead of using system() to run command-line programs, you can add a default gateway route by ioctl with SIOCADDRT and SIOCDELRT, it's very simple.
Hope this helps someone.
Hi,
I want to end a host (shell script based) concurrent program in WARNING. Is it possible? Tried out a few things but it just either ends in NORMAL or ERROR. :confused:
Any ideas/inputs would be appreciated.
Thanks,
coolblue_3 (2 Replies)
hi, linux gurus...
i'm trying to write a script in ksh called ResetPass that allows a user to change mysql passwords. the script accepts user, password and host like this: ResetPass <user> <password> <host>. here's the code:
*****************************************************
mysql... (1 Reply)
I have my Mac OS X program executing a shell script (a script that copies files to a drive). I want to make it so that the shell script automatically kills itself if it finds that the host .app is not running OR kill itself if the drive that it is copying files to has been unmounted. Right now what... (2 Replies)
I need to know what is the maximum stack size i.e. -Xss my java program is running with.
Is there a way to find that out from inside my java program code and outside of it.
What i am looking for is to read whatever the current set max limit -Xss (stack sie) is for a particular JVM(not... (3 Replies)
Can anyone suggest a workaround
zone_5.org='/qaz/qwe/path/tns.osn'
output
/home/bingo/XXX_script.sh: line 180: zone_5.org=/qaz/qwe/path/tns.osn: no parent
The path does not exist on the local machine, the allocation used to work till the server was upgraded.
Red Hat Enterprise Linux... (2 Replies)
I have an Oracle Linux 7.1 vsphere host built. It's be preconfigured with our security configurations.
What I would like to do is unconfigure this host. Then set the host to do firstboot --reconfigure.
how do I do that using /etc/sysconfig/firstboot?
I've tried setting
... (10 Replies)
Hi All,
I have a requirement to make a oracle concurrent program end with
warning based on a given condition. If the condition is true, the
concurrent program should end with completed warning status.
The host program I am using is a shell script that checks if a file exists.
... (2 Replies)
Hi all,
i have a rhel 6.2 with a default gateway.
This server is an Intranet office with no internet access.
DNS are already configured and it's possible to resolve my target.
My goal is to link my application (apache forward) only to http://mytarget.yyy through a new gateway (That does... (0 Replies)
Dear friends
I use RedHat 6.5, which sets the gateway in the configuration file / etc / sysconfig / network as GATEWAY = 192.168.1.26, and the gateway in the configuration file / etc / sysconfig / network-scripts / ifcfg-eth11 as GATEWAY = 192.168.1.256. The two gateways are different.... (6 Replies)
Discussion started by: tanpeng
6 Replies
LEARN ABOUT SUSE
sendmmsg
SENDMMSG(2) Linux Programmer's Manual SENDMMSG(2)NAME
sendmmsg - send multiple messages on a socket
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <sys/socket.h>
int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen,
int flags);
DESCRIPTION
The sendmmsg() system call is an extension of sendmsg(2) that allows the caller to transmit multiple messages on a socket using a single
system call. (This has performance benefits for some applications.)
The sockfd argument is the file descriptor of the socket on which data is to be transmitted.
The msgvec argument is a pointer to an array of mmsghdr structures. The size of this array is specified in vlen.
The mmsghdr structure is defined in <sys/socket.h> as:
struct mmsghdr {
struct msghdr msg_hdr; /* Message header */
unsigned int msg_len; /* Number of bytes transmitted */
};
The msg_hdr field is a msghdr structure, as described in sendmsg(2). The msg_len field is used to return the number of bytes sent from the
message in msg_hdr (i.e., the same as the return value from a single sendmsg(2) call).
The flags argument contains flags ORed together. The flags are the same as for sendmsg(2).
A blocking sendmmsg() call blocks until vlen messages have been sent. A nonblocking call sends as many messages as possible (up to the
limit specified by vlen) and returns immediately.
On return from sendmmsg(), the msg_len fields of successive elements of msgvec are updated to contain the number of bytes transmitted from
the corresponding msg_hdr. The return value of the call indicates the number of elements of msgvec that have been updated.
RETURN VALUE
On success, sendmmsg() returns the number of messages sent from msgvec; if this is less than vlen, the caller can retry with a further
sendmmsg() call to send the remaining messages.
On error, -1 is returned, and errno is set to indicate the error.
ERRORS
Errors are as for sendmsg(2). An error is returned only if no datagrams could be sent. See also BUGS.
VERSIONS
The sendmmsg() system call was added in Linux 3.0. Support in glibc was added in version 2.14.
CONFORMING TO
sendmmsg() is Linux-specific.
NOTES
The value specified in vlen is capped to UIO_MAXIOV(1024).
BUGS
If an error occurs after at least one message has been sent, the call succeeds, and returns the number of messages sent. The error code is
lost. The caller can retry the transmission, starting at the first failed message, but there is no guarantee that, if an error is
returned, it will be the same as the one that was lost on the previous call.
EXAMPLE
The example below uses sendmmsg() to send onetwo and three in two distinct UDP datagrams using one system call. The contents of the first
datagram originates from a pair of buffers.
#define _GNU_SOURCE
#include <netinet/ip.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
int
main(void)
{
int sockfd;
struct sockaddr_in addr;
struct mmsghdr msg[2];
struct iovec msg1[2], msg2;
int retval;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1) {
perror("socket()");
exit(EXIT_FAILURE);
}
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr.sin_port = htons(1234);
if (connect(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == -1) {
perror("connect()");
exit(EXIT_FAILURE);
}
memset(msg1, 0, sizeof(msg1));
msg1[0].iov_base = "one";
msg1[0].iov_len = 3;
msg1[1].iov_base = "two";
msg1[1].iov_len = 3;
memset(&msg2, 0, sizeof(msg2));
msg2.iov_base = "three";
msg2.iov_len = 5;
memset(msg, 0, sizeof(msg));
msg[0].msg_hdr.msg_iov = msg1;
msg[0].msg_hdr.msg_iovlen = 2;
msg[1].msg_hdr.msg_iov = &msg2;
msg[1].msg_hdr.msg_iovlen = 1;
retval = sendmmsg(sockfd, msg, 2, 0);
if (retval == -1)
perror("sendmmsg()");
else
printf("%d messages sent
", retval);
exit(0);
}
SEE ALSO recvmmsg(2), sendmsg(2), socket(2), socket(7)COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the
latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Linux 2018-02-02 SENDMMSG(2)