Warn when a table module reads from an interactive terminal

[Esteban82]

When a module that reads a data table (blockmean, gmtinfo, psxy, triangulate, surface, mapproject, etc.) is run with no input file and no piped/redirected data, GMT falls back to reading from standard input. If you run it directly in a terminal — often just because you forgot the input file — the command appears to hang, with no indication of what it's waiting for.

Now a message appears in that case:

gmt gmtinfo
gmtinfo [WARNING]: No input file given - reading table data from standard input
(this terminal). Type your data and press Ctrl-D when done. To use a file or a
pipe instead, press Ctrl-C now and rerun the command with that input.

It's currently a warning, so the command keeps waiting on stdin as before (you can still type data and finish with Ctrl-D).

Question:
Would a hard error instead be preferred, so it exits immediately instead of continuing to wait?

Assisted by Claude Opus 5

[joa-quim]

gmtinfo is a particular module. All other mentioned here (blockmean, etc) print the online help when only the program names is typed. I think this would introduce unnecessary complication for very little gain to distinguish when options were passed but not the file name

[Esteban82]

Fair point, gmtinfo was a bad example — it's the only one here with no required options, so it's the only one that reaches this code on a bare invocation.

Tested with blockmean:

gmt blockmean → full module usage (as you said)
gmt blockmean -I1 → "must specify -R option" error
gmt blockmean -I1 -R0/10/0/10 → the new message. Only fires when the table is the sole thing missing.

[seisman]

I'm also against such changes.

If I understand it correctly, the error message only appears in interactive terminals. But in the real world, it's more common to run GMT commands from scripts, so the changes add little to GMT.