Perl Mapscript 3.5+ Debugging

Submitted by Aaron D. Hunt <hunt@…>

    $ENV{MS_ERRORFILE} = "/var/log/mapserver.log"; # map engine error log 

near the top of the perl mapscript code... before you initialize your map object. This is an environment variable: MS_ERRORFILE for the shell, or execution instance which catches all of the errors/warning that occur within mapserver and sends them to the filespec defined. This one is the *most* useful log for debugging mapfile errors, index problems, and mapserver internals, etc.

    WEB 
    log "/var/log/mapserver_access.log 
    END 

in the mapfile. you could probably setup that variable in mapscript as well, but I have always put it in the mapfile. It records a set of variables similar to the apache access log for each mapserver execution.

Submitted by Lowell.Filak <lfilak@…>

    #!/usr/bin/perl -w 

    -w posts all Perl warnings to the httpd log file, 
    usually named error_log in /var/log/httpd or /etc/httpd/logs. 

Submitted, in part, by Frank Warmerdam <warmerdam@…>

    /sbin/ldconfig -v 

will give information concerning the shared libraries present on your system.

    echo $LD_LIBRARY_PATH 

Will give information on the library path traversed when linking.

    locate <library_name_ie._gd.h> 

Will give location(s) of the specified filename.

Does the above information show a mixture of include files (different revisions of the same library).

Submitted by Daniel Morissette <dmorissette@…>

    ldd mapserv 

Look for the path that is listed. Then make sure this path is part of your runtime library path, for this you have two options, assuming you're running Linux:

1- add the path to /etc/ld.so.conf and run 'ldconfig' as root

or

2- Use SetEnv LD_LIBRARY_PATH to specify this path in your apache httpd.conf

If when running ./mapserv you receive the error message:

    mapserv:error while loading libraries:libproj.so.0 cannot open shared object file : No such file or directory. 

Run '/sbin/ldconfig -v | grep libproj'.

Which should return something similar to "libproj.so.0" If not try reinstalling proj.4

Submitted by Daniel Morissette <dmorissette@…>

If when running ./mapserv you recieve the error message:

    error while loading shared libraries :/usr/libwwwappp.so.0 undefined symbol: HTZlib_inflate 

Check /usr/lib and /usr/local/lib for a copy of w3c-libwww. If both have a copy then remove the copy in /usr/lib. The cleanest way to remove, is to 'rpm -q -a | grep w3c-libwww' & do 'rpm -e w3c-libwww-<version_number>'.

If you end up with a "core" file from an error and have the GNU debugger installed:

    gdb 
    target core ./core 
    backtrace