PerlMapScriptDebugging

== Submitted by Aaron D. Hunt [email protected] ==

    $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 [email protected] ==

    #!/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 [email protected] ==

    /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 [email protected] ==

    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 [email protected] ==

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                                                                                                      
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