xttpd - Harmonic tide clock and tide predictor (web server)
xttpd [port] [-dc color] [-Dc color] [-df ‘‘format-string’’] [-ec
color] [-el y|n] [-em pSsMm] [-fc color] [-fg color] [-ga aspect] [-gh
pixels] [-gt y|n] [-gw pixels] [-hf ‘‘format-string’’] [-in y|n] [-lw
pixels] [-mc color] [-Mc color] [-nc color] [-nf y|n] [-tf ‘‘format-
string’’] [-tl y|n] [-u ft|m] [-v] [-z y|n]
XTide is a package that provides tide and current predictions in a wide
variety of formats. Graphs, text listings, and calendars can be
generated, or a tide clock can be provided on your desktop.
XTide can work with X-windows, plain text terminals, or the web. This
is accomplished with three separate programs: the interactive interface
(xtide), the non-interactive or command line interface (tide), and the
web interface (xttpd).
xttpd is an XTide web server. It provides web-based access to XTide’s
tide predictions by allowing a web browser to speak directly to the
XTide program in HTTP. xttpd can replace httpd or it can co-exist with
If you run xttpd with no command line arguments, it will assume that it
is replacing httpd and try to bind port 80. If you want it to co-exist
with an existing server, or if you do not have privilege to get port
80, give it the port number as the first command line argument:
% xttpd 8080
You will then need to link it up as http://www.wherever.org:8080/
instead of just http://www.wherever.org/, but otherwise, no damage
done. Similarly, if you wish to bind a specific address, you can
specify that as the first argument:
% xttpd 127.0.0.2
If you need to specify both address and port number, separate the two
with a slash, like this:
% xttpd 127.0.0.2/8080
Once the port is established, xttpd will try to set its UID and GID to
values that were specified at compile time. If it is unable to do
this, it will log failure messages to syslog and then exit.
Consequently, if it is to be started by someone other than root, that
user’s UID and GID must be configured at compile time. Instructions
for doing this are available at
For a complete discussion of the command line options and a detailed
explanation of the XTide package, please see the verbose documentation
Unless a configuration file /etc/xtide.conf is supplied, you must set
the environment variable HFILE_PATH to point to the harmonics files
that should have been installed along with the xtide program. Example:
If a configuration file is used, the first line should consist of the
colon-separated list of harmonics files (e.g. the HFILE_PATH line above
without the "export HFILE_PATH=" part). The environment variable takes
precedence over the configuration file.
CONFIGURATION ON DEBIAN SYSTEMS
On Debian systems the web server xttpd may optionally be started at
boot time by editing /etc/init.d/xttpd (setting the PORT variable and
uncommenting out the line). Set the environment variable XTTPD_FEEDBACK
in /etc/init.d/xttpd to change the mail feedback address.
Also, note that on Debian systems the tidal harmonics data file are
stored in /usr/share/xtide instead of /usr/local/share/xtide as used
Daytime background color in tide graphs (default SkyBlue).
Color of datum line in tide graphs (default white).
strftime(3) style format string for printing dates (default
Foreground in tide graphs during outgoing tide (default
Select whether or not to draw datum and middle-level lines in
tide graphs (default n).
Events to suppress (p = phase of moon, S = sunrise, s = sunset,
M = moonrise, m = moonset), or x to suppress none. E.g, to
suppress all sun and moon events, set eventmask to the value
Foreground in tide graphs during incoming tide (default Blue).
Color of text and other notations (default black).
Aspect for tide graphs (default 1.0). This controls not the
width or height of the window but rather the relative scaling of
the X and Y axes in the plot of the tide curve.
Height for tide graphs (default 312 pixels).
Select whether or not to label tenths of units in tide graphs
Width for tide graphs (default 960 pixels).
strftime(3) style format string for printing hour labels on time
axis (default %l).
Select whether or not to use inferred values for some
constituents (default n). For expert use only.
Width for lines in tide graphs with -nf (default 2.5 pixels).
Color of mark line in graphs (default red).
Color of middle-level line in tide graphs (default yellow).
Nighttime background color in tide graphs (default DeepSkyBlue).
Select whether or not to draw tide graphs as line graphs
strftime(3) style format string for printing times (default
%l:%M %p %Z).
Select whether or not to draw depth lines on top of the tide
graph (default n).
Preferred units of length (default no preference).
-v Print version string and exit.
-z y|n Select whether or not to coerce all time zones to UTC (default
tide(1), xtide(1), http://www.flaterco.com/xtide/.