Re: socket: Undefined

[Stephen Frost <sfrost@ns.snowman.net>]

	Your problem is a linking problem.  You are not linking in the
appropriate libraries.  If you do a 'man socket' you will see that
the first line in the SYNOPSIS is the cc line, which tells you what
libraries you need to link in in order to use the 'socket' function.

SYNOPSIS
     cc  [ flag ... ] file ... -lsocket -lnsl [ library ... ]
     #include <sys/types.h>
     #include <sys/socket.h>

     int socket(int domain, int type, int protocol);

	As you can see, in this case you would need to use 'socket'
and 'nsl'.  So your gcc command would look something like:

gcc -lsocket -lnsl *.c

	You may wish to check the other functions you use to see if
they have other libraries that need to be linked in.

		Stephen

On Mon, 20 Sep 1999, Shicheng wrote:

> I work on SunOS 5.6 platform from a networked NT machine via telnet; and
> I would like to obtain some advice on using the gcc compiler. Under my
> working dir, there are five files: connectsock.c,
> connecttcp.c, connectudp.c, errexit.c and tcpdaytime.c; after issuing
> the commend:
> 
> gcc *.c
> 
> however, I got the following errors:
> 
> "[60]% gcc *.c
> Undefined                      first referenced
> symbol                            in file
> socket                              /var/tmp/cc0heQO31.o
> getprotobyname                      /var/tmp/cc0heQO31.o
> gethostbyname                      /var/tmp/cc0heQO31.o
> getservbyname                      /var/tmp/cc0heQO31.o
> inet_addr                          /var/tmp/cc0heQO31.o
> connect                            /var/tmp/cc0heQO31.o
> ld: fatal: Symbol referencing errors. No output written to a.out"
> 
> In the file connectsock.c, I do include the follwing paths:
> 
> #include "/usr/include/sys/types.h"
> #include "/usr/include/sys/socket.h"
> 
> #include "/usr/include/netinet/in.h"
> #include "/usr/include/netdb.h"
> 
> I even checked all the required files are there under the include dir! I
> had the same errors when using "cc" as well!
> 
> BTW, when trying another simple program which just makes use
> of the #include <stdio.h>, there is no problem/errors at all!
> 
> Thanks for sending me some advice on how to solve this problem.
> 
> Shicheng
> 
> 
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