I have very simple client - server setup, where client connects, exchanges some messages with the server and then closes socket and exits. Everythink works OK, except when I am trying to change socket to be non-blocking AND the shell happens to be plain old Bourne. It runs no problem under ksh or bash. But when I run it under sh the program completes and then it kills the shell and kicks me out.
Below is my code, for simplicity I left the connection part of it as it is enough to highlight the problem:
I run under OpenServer 5.0.7, native compiler.
To avoid having to re-login I start Bourne shell from bash, below is my run session:
See, how the sh is terminated and I am back to bash
As I indicated above, if I don't do fcntl(sh, F_SETFL, val) problem disappears. The server side is not affected in any case.
Hello,
I actually try to make client-server program.
I'm using SCO OpenServer Release 5.0.0 and when I try to compile my code (by TELNET) I've got this error :
I'm just using this simple code :
and I get the same error if I use :
If someone can help me,
Thanks (2 Replies)
hi, I need to know how to lock a file. I used the following code, but after executing the program the file 'write.txt' remined empty, and I have no idea why.Maybe I'm not using the corresponding syntax for blocking a file. But I deleted then the blocking part and the problem persisted.
see to... (2 Replies)
Hi,
I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime.
To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
Hi all,
On the server side, one socket is used for listening, the others are used for communicating with the client.
My question is: if i want to set option for socket, which socket should be set on?
If either can be set, what's the different?
Again, what's the different if set option... (1 Reply)
Hi,
Unless I am missing some serious differences in Mac and linux in terms of C programming, I dont know why this would happen. Please take a look at the following piece of code fragment:
bool add_input_to_db(Cons *new_data) {
// Set the attributes of the lock
struct flock fl =... (3 Replies)
Why does this socket function only read the first 1440 chars of the stream. Why not the whole stream ? I checked it with gdm and valgrind and everything seems correct...
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include... (3 Replies)
Dear Experts,
i am compiling my code in suse 4.1 which is compiling fine,
but at runtime it is showing me for socket programming error no 88
as i searched in errno.h it is telling me socket operation on non socket,
what is the meaning of this , how to deal with this error , please... (1 Reply)
I need clarification on whether it is okay to set socket options on a listening socket
simultaneously when it is being used in an accept() call?
Following is the scenario:-
-- Task 1 - is executing in a loop - polling a listen socket, lets call it 'fd', (whose file descriptor is global)... (2 Replies)
Hello
I have a Perl script that works on non-darwin Mac OS X environments and I think I have narrowed down the issue to a file locking problem.
In other linux environments, the flock struct is defined differently. I have adjusted this via the reference for Mac OS X fcntl(2) man page. The... (4 Replies)
Good evening, friends
I'm learning with a book: Programming Linux by Kurt Wall (Prentice Hall)
The code below could run in two windows (./lockit /tmp/foo in both for example). There is not problem with the read block (first byte) but when one, apply the write block while in the other is... (1 Reply)
Discussion started by: joe_cosmo
1 Replies
LEARN ABOUT REDHAT
socket
socket(n) Tcl Built-In Commands socket(n)
__________________________________________________________________________________________________________________________________________________NAME
socket - Open a TCP network connection
SYNOPSIS
socket ?options? host port
socket -server command ?options? port
_________________________________________________________________DESCRIPTION
This command opens a network socket and returns a channel identifier that may be used in future invocations of commands like read, puts and
flush. At present only the TCP network protocol is supported; future releases may include support for additional protocols. The socket
command may be used to open either the client or server side of a connection, depending on whether the -server switch is specified.
CLIENT SOCKETS
If the -server option is not specified, then the client side of a connection is opened and the command returns a channel identifier that
can be used for both reading and writing. Port and host specify a port to connect to; there must be a server accepting connections on
this port. Port is an integer port number and host is either a domain-style name such as www.sunlabs.com or a numerical IP address such as
127.0.0.1. Use localhost to refer to the host on which the command is invoked.
The following options may also be present before host to specify additional information about the connection:
-myaddr addr
Addr gives the domain-style name or numerical IP address of the client-side network interface to use for the connection. This
option may be useful if the client machine has multiple network interfaces. If the option is omitted then the client-side interface
will be chosen by the system software.
-myport port
Port specifies an integer port number to use for the client's side of the connection. If this option is omitted, the client's port
number will be chosen at random by the system software.
-async The -async option will cause the client socket to be connected asynchronously. This means that the socket will be created immedi-
ately but may not yet be connected to the server, when the call to socket returns. When a gets or flush is done on the socket before
the connection attempt succeeds or fails, if the socket is in blocking mode, the operation will wait until the connection is com-
pleted or fails. If the socket is in nonblocking mode and a gets or flush is done on the socket before the connection attempt suc-
ceeds or fails, the operation returns immediately and fblocked on the socket returns 1.
SERVER SOCKETS
If the -server option is specified then the new socket will be a server for the port given by port. Tcl will automatically accept connec-
tions to the given port. For each connection Tcl will create a new channel that may be used to communicate with the client. Tcl then
invokes command with three additional arguments: the name of the new channel, the address, in network address notation, of the client's
host, and the client's port number.
The following additional option may also be specified before host:
-myaddr addr
Addr gives the domain-style name or numerical IP address of the server-side network interface to use for the connection. This
option may be useful if the server machine has multiple network interfaces. If the option is omitted then the server socket is
bound to the special address INADDR_ANY so that it can accept connections from any interface.
Server channels cannot be used for input or output; their sole use is to accept new client connections. The channels created for each
incoming client connection are opened for input and output. Closing the server channel shuts down the server so that no new connections
will be accepted; however, existing connections will be unaffected.
Server sockets depend on the Tcl event mechanism to find out when new connections are opened. If the application doesn't enter the event
loop, for example by invoking the vwait command or calling the C procedure Tcl_DoOneEvent, then no connections will be accepted.
CONFIGURATION OPTIONS
The fconfigure command can be used to query several readonly configuration options for socket channels: |
-error |
This option gets the current error status of the given socket. This is useful when you need to determine if an asynchronous connect |
operation succeeded. If there was an error, the error message is returned. If there was no error, an empty string is returned.
-sockname
This option returns a list of three elements, the address, the host name and the port number for the socket. If the host name cannot
be computed, the second element is identical to the address, the first element of the list.
-peername
This option is not supported by server sockets. For client and accepted sockets, this option returns a list of three elements; these
are the address, the host name and the port to which the peer socket is connected or bound. If the host name cannot be computed, the
second element of the list is identical to the address, its first element.
SEE ALSO
flush(n), open(n), read(n)
KEYWORDS
bind, channel, connection, domain name, host, network address, socket, tcp
Tcl 8.0 socket(n)