gmt sac and segy error in modern mode

[seisman]

Description of the problem

gmt sac - reports sac module not found.

gmt sac -
gmt [ERROR]: Shared GMT module not found: sac

ERROR: No module named sac was found.  This could mean one of four cases:
  1. There actually is no such module; please check your spelling.
  2. You used a modern mode module name while running in GMT classic mode.
  3. Module exists in the GMT supplemental library, but the library could not be found.
  4. Module exists in a GMT custom library, but none was specified via GMT_CUSTOM_LIBS.
Shared libraries must be in standard system paths or set via environmental parameter DYLD_LIBRARY_PATH.

gmt segyz displays the usage of segy, not segyz.

gmt segyz -
gmt segy [segy] 6.0.0_0ef8a85_2019.03.19 [64-bit] - Plot a SEGY file on a map in 3-D

usage: gmt segy [<segyfile>] -D<dev> -F<color> | -W -Jx|X<args>
	-R[<unit>]<xmin>/<xmax>/<ymin>/<ymax>[+r] [-A] [-C<clip>] [-E<slop>] [-I] [-K] [-L<nsamp>]
	[-M<ntraces>] [-N] [-O] [-P] [-Q<mode><value>] [-S<header>] [-T<tracefile>]
	[-U[<label>][+c][+j<just>][+o<dx>/<dy>]] [-V[<level>]] [-W] [-X[a|c|f|r]<xshift>[<unit>]]
	[-Y[a|c|f|r]<yshift>[<unit>]] [-Z]
	[-p[x|y|z]<azim>[/<elev>[/<zlevel>]][+w<lon0>/<lat0>[/<z0>][+v<x0>/<y0>]] [-t<transp>] [--PAR=<value>]