Account Overview - Getting Started - Control Panel Overview - Chapter 1 FTP Software Setup
Chapter 2 SSH / Telnet Setup - Chapter 3 Email Software Setup - Chapter 4 CGI-Bin - Chapter 5 Secure Server
Chapter 6 FormMail - Chapter 7 MS FrontPage - Chapter 8 CGI Scripts - Chapter 9 ASP - Active Server Pages
Chapter 10 JSP - Java Server Pages - Chapter 11 PHP - Chapter 12 Real Audio/Real Video
Chapter 13 File Manager - Chapter 14 Mail Manager - Chapter 15 Changing Passwords - Chapter 16 Site Statistics
Chapter 17 Network Tools - Chapter 18 FTP Manager - Chapter 19 Backup Manager - Chapter 20 Password Protect Directories
Chapter 21 Custom Error Pages - Chapter 22 MySQL & PhpMyAdmin - Chapter 23 Mime Types - Chapter 24 CronTab
Chapter 25 Entropy Chat - Chapter 26 Akopia Shopping Cart - Chapter 27 Search Engine Submission
Chapter 28 PGP & PGP Mail - Chapter 29 Subdomains

Chapter 4
CGI Script Info, Server Paths, Permissions, & SSI Server Side Includes Guidelines



CGI-bin General Information

CGI stands for "Common Gateway Interface," a fancy name meaning computer programs running on the web server that can be invoked from a www page at the browser. The "bin" part alludes to the binary executables that result from compiled or assembled programs. It is a bit misleading because cgi's can also be Unix shell scripts or interpreted languages like Perl. CGI scripts need to be saved in ASCII format and uploaded to your server's cgi-bin in ASCII or text format. This is very important.

This chapter provides you with information needed when configuring scripts and other information regarding your CGI-bin.




Where to put CGI scripts

Put your cgi-bin scripts in the public_html subdirectory named "cgi-bin".




Paths to Date, Mail, Perl, etc.

Here are your paths to the common server resources that CGI scripts often require:

Date:  /bin/date

Sendmail: /usr/lib/sendmail

Perl5:  #!/usr/bin/perl

Serverpath: /home/username/public_html/cgi-bin

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



How To Set Permissions

There are three different ways to set permissions for your files and directories within your account. 1) File Manager, 2) FTP, and 3) Telnet. We DO NOT encourage the use of Telnet if it is only being used for setting permissions and will forego its explanation here.

Setting Permissions Using Your File Manager:

Log into your Control Panel and then click on File Manager. You will now see a list of directories within the root of your account. Since all of your html files and subdirectories are uploaded and created within your public_html directory you need to click on the file folder next to the public-html directory name. The directory will open and in the upper right hand corner, there will be a list of actions that you can perform for that directory. Next click on the file icon located next to the text name of the file that you are wanting to change permissions for. Again, in the upper right hand corner you will see a list of actions that you can perform with this file, simply click on Change Permissions and select the appropriate permissions and save.

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.






Permission Definitions

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

Permissions Definitions:

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

Numerical Definitions:

r = 4
x = 2
w = 1

You will come to recognize, if you do not already, 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.




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

You are probably using the wrong reference for cgiemail. Use the reference /cgi-bin/cgiemail/mail.txt. Another 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.



Quick Guidelines To SSI (Server Side Includes)

SSI's allow you to create documents which include other documents and various dynamically generated information, such as the current date, the file's last modification date, and the size or last modification of other files. Note: The "exec" command is not available, due to security considerations.

NOTE: Special File Extension Necessary

Files utilizing includes must be created using the ".shtml" extension. If they do not, the includes will be ignored.

The "include" format - All include directives are formatted as SGML comments within your document. This is in case the document should ever be transferred without being parsed.

Each directive has the following format:

<!--#command tag1="value1" tag2="value2" -->

Each command takes different arguments, most only accept one tag at a time. Here is a breakdown of the commands and their associated tags:

include Inserts the text of a specified document into the body of the current document. Is commonly used for including headers or footers in web pages.

<!--#include virtual="/dir/file.ext"-->
<!--#include file="subdir/file.ext"-->

Notes:
Do not leave any spaces between the equal ("=") sign and the file it specifies. Doing so will cause an error message to be displayed.

Any included file is subject to the usual access authorization controls. If you use a domain name you must use the virtual command. file only works with WebCom URLs.

virtual gives a virtual path to a document on the server. A normal file or another parsed document may be accessed using this tag. Please note that the path of this file name should be the URL of the file, with the domain name removed, and the userid added. For instance, if the URL of a file is "http://www.your-domain.com/products/footer.txt" and your userid is "userid" then the path to use with this include directive would be: "/userid/products/footer.txt" Example: <!--#include virtual="/virtual_sample.txt"-->

This is a sample text file. It was included in this file by the include virtual tag:
<!--#include virtual="/webcom/virtual_sample.txt"-->.

This paragraph includes a hotlink, and tags such as bold and emphasis.

file gives a pathname relative to the current directory. ../ cannot be used in this pathname, nor can absolute paths be used. (If you need to refer to a file in a higher directory, you might consider using virtual described above.) As above, you can send other parsed documents. Example: <!--#include file="sample.txt"-->

This is a sample text file. It was included in this file by the include file tag:
<!--#include file="sample.txt"-->.

This paragraph includes a hotlink, and tags such as bold and emphasis.

Other Commands:

echo prints the value of one of the include variables (select the hotlink for definitions). The only valid tag to this command is var, whose value is the name of the variable you wish to echo. <!--#echo var="DOCUMENT_NAME"-->

Result: welcome.shtml

fsize prints the size of the specified file. Valid tags match those of the include command. The resulting format of this command is subject to the sizefmt parameter of the config command. <!--#fsize file="sample.txt"-->

Result: 1K (without sizefmt)

<!--#config sizefmt="bytes"-->
<!--#fsize file="sample.txt"-->

Result: 329 (with sizefmt)

flastmod prints the last modification date of the specified file. Valid tags are the same as with the include command.
<!--#flastmod file="sample.txt"-->

Result: Thursday, 13-Jul-95 14:40:33

config The config directive controls various aspects of the file parsing. There are two valid tags:

errmsg controls what message is sent back to the client if an error includes while parsing the document. When an error occurs, it is logged in the server's error log.

<!--#config errmsg="[This directive failed miserably!]"-->
<!--#include file="does_not_exist.txt"-->

Result: [This directive failed miserably!]

sizefmt determines the formatting to be used when displaying the size of a file. Valid choices are bytes, for a formatted byte count (formatted as 1,234,567), or abbrev for an abbreviated version displaying the number of kilobytes or megabytes the file occupies.
<!--#config sizefmt="bytes"-->








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