Details of Perl Setup
- The Perl "path" is the same as is visible via FTP. For example,
the path to your tmp directory is /tmp, and the path to your document
root is /docs
- Socket functions are disabled
- All Perl scripts must be in the /cgi-bin directory to execute. They must be set with the execute bit on (chmod 755).
- Always upload Perl and HTML in ASCII mode in your FTP Client.
Perl scripts uploaded in binary mode will result in an 'Internal Server
Error'
- To send email from your Perl scripts, you should use SMTP Auth
from mail.domain.com, where domain.com is your actual domain name. You
will need to properly authenticate with your SMTP username and password.
- The the path to Perl is:
#!/usr/bin/perl
Correct file permissions for a Perl script
Permissions are often set very leniently in order to avoid
permissions problem. This is not a good idea. Your Perl scripts should
have the appropriate permissions depending on the function of that
particular script.
First, all scripts should be set to the owner (you) having read,
write and execute privilege (rwx) regardless of the function of the Perl
script.
Next, you should ask yourself if you want people (visitors) to
your Web site to be able to execute the Perl script. This is most likely
the case. Under these conditions, your script would be set to world
readable and execuable (r-x). Do not give everyone write permission on
the Perl script; it is not necessary and may lead to problems.
If your script is not going to be executed through the Web and
only you will be executing the script through Telnet (there are various
reasons for having a script operate under these conditions), then you
set the script to no world permissions (---).
The group permissions should be set to read and executable (r-x)
if the script is to be executable via the Web. Otherwise, set your group
permissions to nothing (---).
With this information, you have the following permissions breakdown:
Executed via the Web by anyone: chmod 755
Often times, a Perl script will open a file for writing. This is
the case in guestbooks and bulletin boards, where the information is
received from the form and written to a certain file. The permissions of
this particular file are now important.
Many times, the author of a Perl script you use on your account
will require you to set this file to rwxrw-rw-, or chmod 766, which
allows write access to the world. This is not a good idea and is
unnecessary.
Files that need to be written to by way of a Perl script can be
set to the default permissions of rw-r--r--, or chmod 644. This will
work fine with our setup.
Finally, never set your file permissions to rwxrwxrwx, or chmod
777. This is not necessary, may cause a security problem on your Web
site, and will cause your Perl script to not execute at all.
ASCII or Binary Mode Uploads
You should always upload your Perl scripts in ASCII mode via FTP. If
you upload your scripts in binary mode, the scripts will not work and
you will get an "Internal Server Error: Premature End of Script Headers"
error (500 Internal Server Error). It is very important to remember to
only upload your Perl scripts in ASCII mode.
Images used with Perl Scripts
Your cgi-bin folder is a special folder for your scripts. Place all
static content, including HTML and image files under your docs folder or
its sub-folders.
Internal Server Errors
There are several causes for this problem:
- Make sure your path to Perl executable is set as #!/usr/bin/perl in your first line of Perl scripts.
- You have set the executable bit to your files, in other words, you need to set the file permissions (chmod) to 755.
- You need to place all your Perl scripts under cgi-bin folder or its subfolders.
- Make sure you upload all your Perl scripts in ASCII mode in your FTP client.
