Administrating the Server
Here is a reference to setting up, maintaining and utilizing the information and
resources provided by your server.
How to:
Constructing URLs to your server
Now that you have an http server, you'll want to reference it in your HTML
documents and with your favorite Web browser.
Before you do anything, you should read the Beginners guide to URLs to
familiarize yourself with URLs. You will want to pay attention to the section
referring to HTTP URLs.
Definition
HTTP URLs have the basic form:
http://servername:port/path
servername
Your server's full hostname. It can be the server's real name or a DNS alias.
port
This is the port which your server is listening on. Specifying it in the URL is
optional. If omitted, it is assumed to be 80.
If your ServerType is inetd, your port number was set in
/etc/services.
If your ServerType is standalone, the Port directive set your port number.
path
This is the path to the document. This is not the absolute pathname of the
document on your machine.
The server translates path as follows:
1. It looks for any defined Alias or ScriptAlias virtual names at the beginning
of path. If it finds one, it replaces the virtual name with the real name and
processes the request.
2. It looks for a prefix of /~, and if UserDir is not DISABLED, it will look in
the user's public html subdirectory for the file.
3. It inserts DocumentRoot at the beginning of path and processes the
request.
Setting up your Home Page
Some HTTP servers let you explicitly set up your home page (i.e. the page
returned by the URL http://yourserver/ ).
To do this using NCSA httpd, create a DirectoryIndex file in the
DocumentRoot directory.
Note that this index can be a symbolic link to another file.
Examples
My Resource Configuration file contains the following directives (among
others):
DocumentRoot /u/Web
DirectoryIndex index.html
ScriptAlias /htbin /usr/local/etc/httpd/htbin
Alias /zftp /archive/ftp
An HTML document references
http://hoohoo.ncsa.uiuc.edu/docs/Overview.html. The
server finds no Alias or ScriptAlias virtual names in path, so it returns the
file /u/Web/docs/Overview.html.
Someone references my home page as
http://hoohoo.ncsa.uiuc.edu/. The server finds no virtual names,
so it returns /u/Web/index.html.
Another HTML document references
http://hoohoo.ncsa.uiuc.edu/htbin/uptime. The server
finds the ScriptAlias /htbin at the beginning of path, and so executes the
script /usr/local/etc/httpd/htbin/uptime.
Another HTML document references
http://hoohoo.ncsa.uiuc.edu/zftp/README.txt. The server
finds the Alias /zftp at the beginning of path, and returns the file
/archive/ftp/README.txt.
Managing the standalone daemon
Info on Restarting or Terminating the standalone daemon If you are using a
ServerType of inetd, you do not need to read these instructions.
If you make any changes to httpd's configuration files, you must restart the
server. To do so, you will need to know where the server has logged its
process id, given by the server configuration directive PidFile.
If pidfile is the setting of PidFile for your server, to restart the daemon
execute the following on the command line:
kill -1 `cat pidfile`
This will restart the daemon.
You should now check to see if the daemon restarted successfully. Check the
last line of the server's error log, given by the server configuration directive
ErrorLogFile, and make sure it says httpd: successful restart.
Alternatively, you may use the ps command to grep for the process id of
the daemon.
If you ever need to terminate the server, use the following command:
kill `cat pidfile`
Managing the Log Files
If you are using a ServerType of inetd, you may remove or move the log
files periodically using mv or rm with no effect on the server.
The standalone daemon opens the log files once when it starts up, and does not
close them until killed. This is because the fopen() system call has a lot of
overhead.
To rotate one of the log files, do the following:
1. Move the log file to a new name with the mv command
2. Restart the standalone daemon
This will cause all new server processes to log to the new log file. You may
then do what you wish with the old log file.
The Improved imagemap Script
Eternal gratitude to Kevin Hughes, kevinh@pulua.hcc.hawaii.edu, for his
code to find intersections of points with circles and polygons.
Compile the imagemap script
If you downloaded the source, you need to compile the imagemap script. Do
this by first cd'ing into your ServerRoot, and then cd into the cgi-src
subdirectory. Then, type make imagemap and you should be all set.
The Central Configuration File
The imagemap script expects to find its configuration file as:
/usr/local/etc/httpd/conf/imagemap.conf.
If you would like to change the location of this file, edit
cgi-src/imagemap.c, change the setting of CONF_FILE, and
recompile with make imagemap.
In this file, lines beginning with a # are comments. Every other non-blank
line consists of:
name : path
name is the name of the particular mapping. You use it when you reference
the image.
path is the full path to the map configuration file for this mapping.
Notice: It is important to leave a space before and after ":". It is also
important to finish your lines with <CR>.
The Map Configuration File
This file maps regions to URLs for the given image.
Lines beginning with # are comments. Every other non-blank line consists of
the following:
method url coord1 coord2 ... coordn
coord are each coordinates, format x,y. The number depends on method.
method is one of the following:
circle
For a circle. Coordinates: center edgepoint
poly
For a polygon of at most 100 vertices. Each coordinate is a vertex.
rect
For a rectangle. Coordinates: upper-left lower-right
url is one of the following:
a virtual pathname to a file on your server (i.e. a URL to your server
without the http://hostname part)
a URL
Note: each method is evaluated in the order it is placed in the configuration
file. If you have overlapping areas, such as a circle inside of a rectangle, you
should place whichever one you want evaluated first before the other in the
map file. In this case, we would put the circle before the rectangle.
Referencing Your New Map
To reference your new map, you construct URLs pointing to it.
For example, if you have a ScriptAlias /cgi-bin/
/usr/local/etc/httpd/cgi-bin/, named your map fish, and used
the image fish33.gif for the map, the following line of HTML will reference
it:
<A HREF="/cgi-bin/imagemap/fish"><IMG
SRC="fish33.gif" ISMAP></A>
A Complete Example
The fish demo in another section of this manual used the following
configuration files:
Central Configuration File
fish : /usr/local/etc/httpd/conf/fish.map
Map Configuration File
The map configuration file used for this picture was rather lengthy. I used xv
to get the coordinates.
Write CGI scripts to handle forms
Get the documents on CGI scripts and read those.
Use server side includes in your HTML
documents
Get the tutorial documents and read section on server side includes.
Managing Users
To use user authentication, you'll need to edit and manage user files and group
files.
Using htpasswd to manage user files
To deal with user files, we provide a program in the support directory of the
distribution called htpasswd. Usage:
htpasswd [-c] file user
The -c, if present, tells htpasswd to create a new passwd file of the specified
name instead of editing an old one. file is the pathname of the user file you
wish to edit. The user parameter is the name of the user you wish to add or
edit.
If htpasswd finds the user you specified, it will ask you to change the user's
password. Type the new password (it will ask twice). httpd will then update
the file.
If htpasswd doesn't find the specified user, it will ask you to give the user an
initial password.
Group files
The format of the group file is as follows:
groupname: member1 member2 ...
Or, each line contains the name of a group, and a list of members separated by
spaces.
Edit the configuration files
Get the documents on Installation and read the sections on Configuration.