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tide(1)			    General Commands Manual		       tide(1)

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

SYNOPSIS
       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 ``file-
       name''] [-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]

DESCRIPTION
       XTide is	a package that provides	tide and current predictions in	a wide
       variety of formats. Graphs, text	listings, and calendars	can be	gener-
       ated, 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
       https://flaterco.com/xtide/.

CONFIGURATION
       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.

OPTIONS
       -b ``YYYY-MM-DD HH:MM''
	      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 loca-
	      tion, 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.

       -e ``YYYY-MM-DD HH:MM''
	      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  sup-
	      plied,  the  end	time  will be set to four days after the begin
	      time.

       -ec color
	      Foreground in tide graphs	during	outgoing  tide	(default  Sea-
	      Green).

       -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  nei-
	      ther.   Moreover,	 subordinate station offsets may shift the ac-
	      tual 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	bench-
	      mark,  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 sup-
	      press 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  con-
	      stituents	(default n).  For expert use only.

       -l ``location name''
	      Specify a	location for tide predictions.	You get	the first sta-
	      tion where the name supplied with	-l is a	case-insensitive match
	      with the beginning (or the entirety) of the station's name.  You
	      can  use	the  -l	 switch	more than once if the output format is
	      text, HTML, or CSV.

       -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  de-
	      fault 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 predic-
	      tions 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.	If the format is text,
	      HTML, or CSV, an existing	file will be appended  to;  otherwise,
	      it will be overwritten.

       -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 da-
	      tum.

       -pb y|n
	      Select whether or	not calendar mode inserts a page break and re-
	      peats 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 scal-
	      ing.

       -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).

NOTES
       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.

SEE ALSO
       xtide(1), xttpd(8), https://flaterco.com/xtide/.

XTide 2				  2026-01-17			       tide(1)

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