7.4 What Can Go Wrong?

Many of the errors that can occur with CGI programs produce a page displayed in the browser as shown in Figure 7.6. Pretty helpful, huh?

Figure 7.6. Server error

There could be many causes of this condition. The following are some common things to check.

• The script is syntactically incorrect (try perl -c script.cgi ).

• The first line is not #!/usr/bin/perl .

• There are incorrect file permissions (try chmod a+rx script.cgi or ls-l ).

• There are incorrect directory permissions (be sure the cgi-bin directory has 755 permissions).

You can also run the program from the command line:

 $  ./error.cgi  syntax error at ./error.cgi line 6, near ") chomp"  Execution of ./error.cgi aborted due to compilation errors. 

A clue! The script has a syntax error near line 6.

When all else fails, check the error log file /var/log/httpd/error_log . You might see a line that looks like this:

 syntax error at /var/www/cgi-bin/error.cgi line 6, near ") chomp"  Execution of /var/www/cgi-bin/error.cgi aborted due to compilation  errors. [Fri Mar 25 10:23:17 2002] [error] [client 127.0.0.1] Premature  end of script headers: /var/www/cgi-bin/error.cgi 

Aha! Another clue pointing to line 6!