Virtual Web Server Directories and File Permissions

• - /cgi is where you should store and run your cgi scripts from
• - /logs is where your access and error logs are stored
• - /web is where you should store your .html and graphics files
• - /pw is used for User Authentication password files

The directories that appear in your folder are actually links to directories elsewhere.  They have a location that follows a standard format.  That standard format will be given for each directory shown below.  However, you will need to determine a couple directory coordinates.  The first coordinate is a single hexadecimal digit (0-9 and a-e).  The second coordinate is two hexadecimal digits.  To see what they are, run a pwd from your home directory.  The output will show something like

/u/home/8/1A/[login]/www.[domain.com]

The third and fourth directories are where you will find your coordinates.  Please note these, as they will be crucial.  We will refer to these coordinates as x and yy throughout this document.  For example, the above example would be expressed as /u/home/x/yy/[login]/www.[domain.com].

Now, to reset the permissions, you will need to use the following commands.

     - Your web directory should be permission 0750.
          chmod 0750 /u/home/x/yy/[login]

     - Your pw directory should be permission 0710.
          chmod 0710 /u/web/http/pw/x/yy/www.[domain.com]

     - Your cgi directory should be permission 0710.
          chmod 0710 /u/web/http/cgi/x/yy/www.[domain.com]

     - Subdirectories beneath your web directory should be permission 0755.
          chmod 0755 /u/home/x/yy/[login]/subdir

          * Your web files should be permission 0644.
              chmod 0644 filename

                   5 -rw-r--r--   1 login     login         4607 May 13 12:24 index.html

          * cgi-bin programs should permission 0750.
              chmod 750 cgi-filename

                  14 -rwx------   1 login     login        12322 May 13 12:00 mail*

          * data files your cgi program needs to read from should be permission 0400
              chmod 400 filename

                   1 -r--------   1 login     login           46 May 13 12:28 mail.list

          * files your cgi program needs to read from AND write to should be permission 600
              chmod 600 filename

                   1 -rw-------   1 login    login           46 May 13 12:28 datafile

          * If you install an htpasswd file in your pw directory, the permissions for that should be set to 0644.
              chmod 0644 filename

                   1 -rw-r--r--   1 login     login            5 May 19 14:44 .htpasswd
 

CGI /tmp Usage Tips & Suggestions

There's a link named 'tmp' in your home directory that points to a directory just for you named /tmp/login (replacing the 'login' part with your virtual web login name). By using this tmp file for CGI temporary files, you help to keep the /tmp directory more orderly, and help prevent the possibility that your temporary files will collide with another virtual web's. Since /tmp gets cleaned up occasionally, your CGI should first test for the existance of your /tmp subdirectory first, just to be safe. If it doesn't exist, the CGI should create it: (perl example, remember to run CGIs that write as setuid, as described in the "Virtual Web Server Directories and File Permissions" bulletin...)

             if ( ! -d '/tmp/login')
             {
                     mkdir('/tmp/login', 0700);
             }

name the temporary file uniquely. Even though you have one cgi, it's still possible/probable that the cgi will need to run side-by-side with itself. A good way to accomplish this is to name the file with the PID number in the filename. (Perl and shell variable: $$, C function: getpid()) It's also a good idea to add some unique id to the filename for every different cgi you have that creates temporary files; for example if you had cgi's named c1 and c2, you could begin the temporary file filename with 'c1-' or 'c2-' and append the PID number.

Have your cgi's clean up after itself by removing the temporary file before ending the program.
 

Those Pesky Control-M's

In normal HTML editing, this is not a problem, since the web server handles line separation both ways. However, when working with Perl or Shell scripts, it's very important that lines are terminated UNIX style.

Here's why...

The first line of a perl or shell script indicates what program is needed to interpret the script. For example:

        #!/usr/local/bin/perl
 

indicates that the script needs to be interpreted by perl. If the lines are separated by Control-M Control-J's, the system thinks it reads...

        #!/usr/local/bin/perl^M
 

...which isn't on the system. When an html calls the cgi, you'll get a server error.

To clear out those extra control-M's:

        tr -d '\015' < cgifile > tempfile
        mv tempfile cgifile
 

For information about htaccess files, please read our htaccess file basics page.

For more information on CGI programming, click here.

For a source of ready-made CGI scripts, click here.