"gmt histogram" -I not working

[remkos]

Description of the problem

gmt histogram -I is not working. It returns an error that suggests the module histogram does not exist, even though it does, because plotting with gmt histogram -R... -J... works.

Also gmt pshistogram -I works

Full script that generated the error and error message

$ echo "-1 1\n1 1" | gmt pshistogram -T0.01 -I # Works as expected
-1	1	0	1

$ echo "-1 1\n1 1" | gmt histogram -T0.01 -I   # Does not work
gmt [ERROR]: Shared GMT module not found: histogram

ERROR: No module named histogram 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.

System information

• Operating system: MacOS 15.7.9
• GMT version (gmt --version): 6.7.0 and 6.8.0_d52a1e5_2026.08.03

[Esteban82]

It was not really a bug. gmt histogram is the modern-mode name, so it needs to be run within a modern mode session.
For example:

gmt begin
echo -1 1\n1 1 | gmt histogram -T0.01 -I
gmt end

This works as expected for me.

[remkos]

I did use it in modern mode, but it still did not work. My fix made it work.