Ronny I find that if I can't rely on the documentation to determine which libraries have to be included on the cc commnad line (as sometimes happens), I can track them down with a combination of the nm and grep commands. nm reports the symbols that are defined and/or referenced in a library file. Let's say for instance that, when you build your application, the linker reports that rq_msgs is undefined. To search for the dynamic library that defines this function type the following command sequence from a bourne shell script: cd /usr/lib for f in lib*.so do echo $f nm $f | grep rq_msgs done You will see output similar to this: libhistory.so [664] | 137064| 440|FUNC |GLOB |0 |7 |rq_msgs [397] | 0| 0|FILE |LOCL |0 |ABS |rq_msgs50.c It tells you that rq_msgs in defined in libhistory.so. Therefore you have to add -lhistory to you compilation command to resolve that undefined symbol. If you see the word UNDEF in the second to last field then that library contains code that calls the function but the fucntion is defined in another library file. So you have to keep looking until you find the library file where the fucntion IS defined. This is why you often have to put more than one -lxxx references in your compiler command. Libraries are built by calling functions from other libraries. BTW: -lxxx on the compiler command line is short-hand notation for libxxx.so or libxxx.a. The linker will look for the library file in /usr/lib and in any other directory specified by the -L flags. Another usefull trick is to use the ldd command. If you want to compile for instance an application that retrieves legacy historian data and you know about an existing program or utility that does the same thing, you can use ldd to find out what libraries the program loads at run-time and where it expects to find them. Then you know your program will have to be linked also with at least some of these libraries. Hope this helps. Alain Grumelart Ing. Systems Integration & IT Invensys Process Systems Foxboro Canada Inc. -----Original Message----- From: De Maeyer Ronny [mailto:Ronny.DeMaeyer@xxxxxxxxxx] Sent: Monday, November 18, 2002 2:51 AM To: foxboro@xxxxxxxxxxxxx Subject: [foxboro] data retrieval with legacy historian Hi, I am trying to compile a program to retrieve data from the legacy historian. Following the documentation (BO 193BL rev.e section 8) I use the following syntax cc testhist.c -L/opt/fox/hstorian/bin -I/usr/include/fox -lhist -lisam -lfox -lPW I get the following errors ld: fatal: library -lisam : not found ld: fatal: library -lPW: not found We use the c compiler from SUN, and the legacy historian on ver. 4.3 In witch library could these files be ? I have searched the AW but could not find anything like isam.lib or PW.lib Has anyone any sugestion ? Thanks in advace, Ronny > Ronny De Maeyer > > Fluxys n.v. > LNG TERMINAL ZEEBRUGGE > H.V. Wolvensstraat 3, Kaai 615 > B - 8380 ZEEBRUGGE > Tel.: (++32) (0)50 36 66 24 (direct) > Tel.: (++32) (0)50 36 66 11 (central) > > mailto:ronny.demaeyer@xxxxxxxxxx > http://www.fluxys.net > > > > ************************************************************************** This e-mail and any attachments thereto may contain information which is confidential and/or protected by intellectual property rights and are intended for the sole use of the recipient(s) named above.Any use of the information contained herein (including, but not limited to, total or partial reproduction, communication or distribution in any form) by persons other than the designated recipient(s) is prohibited.Any liability for the correct and complete transmission of the information or for any delay or interruption of the transmission or for damages arising from the use of reliance of the information shall be disclaimed.If you have received this e-mail in error, please notify the sender either by telephone or by e-mail and delete the material from any computer. Thank you for your cooperation ************************************************************************** _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: http://www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: http://www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave