Chapter 26 - CGI-bin

CGI-bin General Information

Where to put CGI scripts

Paths to Date, Mail, Perl, etc.

Sendmail: /usr/sbin/sendmail

Perl5:  #!/usr/bin/perl

Serverpath: /home/username/domain-www/cgi-bin/filename

Root path:  /home/username/
    (puts you in your the root of your account)
	
Domain directory: /home/username/domainname-www
    (puts you in your www directory)
	
Cgi-bin path:  /home/username/domainname-www/cgi-bin
    (puts you in your cgi-bin)

How To Set Permissions

Once inside your www folder, you will see, as in all directories, the first column is the Permissions Column, click on the link pertaining to the directory or file that you wish to set the settings for and the Permissions screen will open as seen in the screen shots below. (Refer to Permission Definitions further down this page for an explanation of settings.

 

Setting Permissions using Fetch for MAC:

If you have Fetch for the Mac, you have an easy way to change permissions. Go to the file you want to change the permissions on, and highlight it. Under the Remote menu, select Change Permissions. A window will pop up showing the current permissions for the file you had highlighted, as shown in the screenshot below. Click on the boxes to change permissions as needed. (Refer to the Permission Definitions further down this page for an explanation of settings.

Setting Permissions Using WS_FTP for Windows:

WS_FTP accomplishes the same task as above. Just highlight the file you want to check, and right-click on it. A menu will pop up, then select CHMOD. You will see the window as shown below in the screenshot we've provided. Click on the appropriate settings as needed. (Refer to the Permission Definitions further down this page for an explanation of settings.

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Permission Definitions

Owner = the files users (you)
Group = the files group
Others = others

Permissions Definitions:

r = read access
w = write access
x = execute access

Numerical Definitions:

r = 4
w = 2
x = 1

Chmod as a word used for changing Permissions from within Telnet or your FTP client.

Some scripts will tell you to chmod 775 (for example). When using the numeric system, the code for permissions is as follows:

4 + 2 + 1 (rwx) = 7

The first number applies to Owner, the second number applies to Group, and the third number applies to Others. Therefore the first 7 of the chmod 775 tells Unix to change the Owner's permissions to rxw (because r=4 + w=2 + x=1 adds up to 7, this giving the Owner Read, Write, and Execute Permission. The second 7 applies to the group, this giving the Group Read, Write, and Execute Permission, and the last number 5, refers to Others (4 + 1= 5), giving Others only Read and Execute Permission. The permissions for chmod 775 look like this: rwx rwx -rx.

Permissions are always broken up into three groups of letters, however if there is a dash, this dash simply means that Permission wasn't given for that particular function, for example in the chmod 775, Permission to Write was not given to Others.

Remember: the first 3 letters always apply to Owner, the second 3 apply to Group, and the third 3 apply to Others.

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Troubleshooting CGI-bin Problems

Below are solutions to some of the more common CGI script problems.

When I activate my CGI program, I get back a page that says "Internal Server Error. The server encountered an internal error or mis-configuration and was unable to complete your request."

This is generally caused by a problem within the script. Check your script settings again to see that you have entered the correct server information and have set the correct permissions for the script. If this information is correct, you'll need to contact whoever wrote or is distributing the script for further assistance.

I am being told "File Not Found," or "No Such File or Directory."

Upload your Perl or CGI scripts in ASCII mode, not binary mode.

When I test my Perl script in local mode (by Telnet), I have the following error: "Literal @domain now requires a back slash at myscript.pl line 3, within string. Execution of myscript.pl aborted due to compilation errors."

This is caused by a misinterpretation by Perl. You see, the "@" sign has a special meaning in Perl; it identifies an array (a table of elements). Since it cannot find the array named domain, it generates an error. You should place a back slash (\) before the "@" symbol to tell Perl to see it as a regular symbol, as in an email address.

I am getting the message "POST not implemented."

A possibility is that you are pointing to a cgi-bin script that you have not put in your cgi-bin directory. In general, this message really means that the web server is not recognizing the cgi-bin script you are calling as a program. It thinks it is a regular text file.

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