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Manual Reference Pages  -  TIDE (1)


tide - Harmonic tide clock and tide predictor (command line client)




tide [-b ‘‘YYYY-MM-DD HH:MM’’] [-cf ‘‘format-string’’] [-ch pixels] [-cw pixels] [-dc color] [-Dc color] [-df ‘‘format-string’’] [-e ‘‘YYYY-MM-DD HH:MM’’] [-ec color] [-el y|n] [-em pSsMm] [-f c|h|i|l|p|t|v] [-fc color] [-fg color] [-ga aspect] [-gh pixels] [-gs d|l|s] [-gt y|n] [-gw pixels] [-hf ‘‘format-string’’] [-in y|n] [-l ‘‘location name’’] [-lb y|n] [-lw pixels] [-m a|b|c|C|g|k|l|m|p|r|s] [-mc color] [-Mc color] [-ml [-]N.NN(ft|m|kt)] [-nc color] [-o ‘‘filename’’] [-ou y|n] [-pb y|n] [-ph mm] [-pi days] [-pm mm] [-pw mm] [-s ‘‘HH:MM’’] [-tf ‘‘format-string’’] [-th characters] [-tl y|n] [-to opacity] [-tw characters] [-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).

tide is the non-interactive command line client for XTide 2. For a complete discussion, please see the verbose documentation at


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:
export HFILE_PATH=/usr/local/share/xtide/harmonics.tcd
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.

Set the environment variable XTIDE_DEFAULT_LOCATION to the name of your favorite place if you want to skip the location-choosing step.


  Specify the begin (start) time for predictions using the ISO 8601 compliant format YYYY-MM-DD HH:MM, where hours range from 00 to 23. The timestamp is in the local time zone for the location, or in UTC if the -z setting is engaged. If clock mode is selected or if no -b is supplied, the current time will be used.
-cf ‘‘format-string’’
  strftime(3) style format string for printing days in calendars (default %a %d).
-ch pixels
  Height for tide clocks (default 312 pixels).
-cw pixels
  Width for tide clocks (default 84 pixels).
-dc color
  Daytime background color in tide graphs (default SkyBlue).
-Dc color
  Color of datum line in tide graphs (default white).
-df ‘‘format-string’’
  strftime(3) style format string for printing dates (default %Y-%m-%d). For calendars see -cf.
  Specify the end (stop) time for predictions in banner, calendar, alt. calendar, medium rare, plain, raw, or stats mode. Does not apply in graph and clock modes: the effective end time for graph and clock modes is entirely determined by the start time (-b), the width (-cw, -gw or -tw), and the aspect (-ga). The format and time zone are the same as for -b. If no -e is supplied, the end time will be set to four days after the begin time.
-ec color
  Foreground in tide graphs during outgoing tide (default SeaGreen).
-el y|n Select whether or not to draw datum and middle-level lines in tide graphs (default n).
The National Ocean Service (NOS) defines both Mean Sea Level (MSL) and Mean Tide Level (MTL) in terms of averages taken over observations. The middle-level line is drawn at the midpoint of the theoretical tidal range, which usually corresponds to the mathematical mean level of the predictions. This approximates both MSL and MTL, but, strictly speaking, is equivalent to neither. Moreover, subordinate station offsets may shift the actual mean so that it no longer falls at the midpoint of the tidal range. The datum line is drawn at the zero level of the predictions, which usually corresponds to the station’s benchmark, but this too can be rendered inaccurate by subordinate station offsets.
-em pSsMm
  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 pSsMm.
-f c|h|i|l|p|t|v
  Specify the output format as CSV, HTML, iCalendar, LaTeX, PNG, text, or SVG. The default is text.
-fc color
  Foreground in tide graphs during incoming tide (default Blue).
-fg color
  Color of text and other notations (default black).
-ga aspect
  Aspect for tide graphs, clocks, and banners (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.
-gh pixels
  Height for tide graphs (default 312 pixels).
-gs d|l|s
  Style of graphs and clocks. Valid values: d (default), l (line), s (semitransparent).
-gt y|n Select whether or not to label tenths of units in tide graphs (default n).
-gw pixels
  Width for tide graphs (default 960 pixels).
-hf ‘‘format-string’’
  strftime(3) style format string for printing hour labels on time axis (default %l).
-in y|n Select whether or not to use inferred values for some constituents (default n). For expert use only.
-l ‘‘location name’’
  Specify a location for tide predictions.
-lb y|n Select whether or not calendar mode inserts a line break before prediction values (default n).
-lw pixels
  Width of line in graph styles l and s (default 2.5 pixels).
-m a|b|c|C|g|k|l|m|p|r|s
  Specify mode to be about, banner, calendar, alt. calendar, graph, clock, list, medium rare, plain, raw, or stats. The default is plain.
-mc color
  Color of mark line in graphs (default red).
-Mc color
  Color of middle-level line in tide graphs (default yellow).
-ml [-]N.NN(ft|m|kt)
  Specify the mark level to be used in predictions. The predictions will include the times when the tide level crosses the mark. Not supported in clock mode. Example usage: -ml -0.25ft
-nc color
  Nighttime background color in tide graphs (default DeepSkyBlue).
-o ‘‘filename’’
  Redirect output to the specified file (appends).
-ou y|n Select whether or not to print numbers with no ft/m/kt (default n). Where possible, adds a header line stating the units and datum.
-pb y|n Select whether or not calendar mode inserts a page break and repeats the station header for each month in text, HTML, and LaTeX formats (default y).
-ph mm Nominal length of paper in LaTeX output (default 420 mm). This need not match your actual paper; use "Shrink oversized pages" in print options.
-pi days
  Number of days of predictions to generate when no end time is specified (default 4).
-pm mm Nominal width of top, bottom, left and right margins in LaTeX output (default 10 mm). Actual width will depend on print scaling.
-pw mm Nominal width of paper in LaTeX output (default 297 mm). This need not match your actual paper; use "Shrink oversized pages" in print options.
-s ‘‘HH:MM’’
  Specify the step interval, in hours and minutes, for raw or medium rare mode predictions. The default is one hour.
-tf ‘‘format-string’’
  strftime(3) style format string for printing times (default %l:%M %p %Z).
-th characters
  Height of ASCII graphs and clocks (default 24 characters).
-tl y|n Select whether or not to draw depth lines on top of the tide graph (default n).
-to opacity
  Opacity of the fill in graph style s (semitransparent) (default 0.65).
-tw characters
  Width of text format (default 79 characters).
-u ft|m 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 n).


If the environment variable TERM is set to vt100 or vt102, tide will take it seriously and invoke the DEC Special Graphics character set in text form output.


xtide(1), xttpd(8),

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XTide 2 TIDE (1) 2014-06-20

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