Frequently Asked Questions

Basic Q&A

Using the Server


Other Features

What is NCSA httpd?

NCSA httpd is a program to serve information, much in the same way that NCSA Mosaic is a program to browse information in the World Wide Web.

httpd stands for HyperText Transfer Protocol (HTTP) Daemon. HTTP is a protocol with the lightness and speed necessary for a distributed collaborative hypermedia information system.

How do I install NCSA httpd?

Read documentation on NCSA httpd Installation.

What is CGI?

CGI stands for Common Gateway Interface. You can read an introduction and an overview.

How do I create and process forms?

First, read a tutorial on creating forms. Then, in order to handle the output from your forms, read how CGI supports forms.
Please make sure that the program doing the "action" must be in the directory specified in ScriptAlias directive, or you will get an error. There are some script to handle "mail form". You can get a copy via anonymous ftp to The directory is /Web/httpd/Unix/ncsa_httpd/cgi/.

How do I setup a clickable imagemap?

Read the documentation on the imagemap script and a tutorial on graphical information maps.

How do I manage user for authentication?

Read the documentation on managing users and a tutorial on user authentication.

How can I perform keyword searches?

You can use WAIS as a back-end search engine. Herein, a tutorial on WAIS and HTTP integration.

How do I set up server-side includes?

You can use server-side includes, to provide data to clients on-the-fly. For example, the current date or the size or last modification date for a file. Check out a tutorial on server-side includes.

How to add environment variables?

You can add environment variables when you use POST method.
For more infomation, please read CGI Environment Variables

What else can I do?

Read the complete documentation on server administration and some provided step-by-step tutorials.

My logfiles are not updated anymore...

This is probably because you moved them or erased them without restarting a standalone daemon. For more information, read the Logfile Management documentation.

Where can I find httpd for MS-Windows/NT?

For information on MS-Windows httpd, please read this page.
For information on Windows NT httpd, please read this page .
Note: Since these server packages are NOT developed by NCSA, we are not responsible for them.

When I submit a form, it gave me 501 error...

The error message says:

We are sorry to be unable to perform the method POST to non-script at this time.

This means the program that performs such "action" is placed in the directory that is not declared in ScriptAlias in your AddType
AddType application/x-httpd-cgi .cgi
in your srm.conf file and change the name of your executable file from "filename" to "filename.cgi".

Can't start server with "gid error"/"setgroupts"

This may caused by the values in User directive and Group directive. The default values for these two directives are all set to -1. These values are not valid on some systems. Please consult with your system administrator to find the valid values.

Can I have hidden variables in forms?

Actually this is handled by the browser (e.g. NCSA Mosaic). In any case, there is an example with hidden variables in the documentation.

Can I have multiple submit buttons?

This is also handled by your browser. NCSA Mosaic for X (v2.5 soon to be released) will have support for multiple submit buttons. See an example to learn how to use them.

What is PGP/PEM encryption?

PGP and PEM are programs to allow you and a second party to communicate in a way which does not allow third parties to read your messages. For more information, there is a PGP/PEM FAQ.

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NCSA httpd Development Team