--delete option is not working properly

[ivok2002]

Environment Information

Open Babel version: 3.1.1
Operating system and version: Windows 10

Expected Behavior

Applying --append and --delete category options at the same time should add the category to the title and then delete it for the output file.

Actual Behavior

Looks like the category is firstly deleted and then added to the output file, producing ?? symbols.
Also there is an error message:
*** Open Babel Error in OpenBabel::OBDescriptor::GetValues
CAT not recognized as a property or a descriptor
1 molecule converted

Steps to Reproduce

obabel --addtotitle "_" --append "@cat" -isdf in.sdf -osdf -Oout.sdf --delete "CAT"

[fredrikw]

Without having your exact file to test on I cannot say for sure but my best suggestion would be to change the command to a piped two-stage command:
obabel --addtotitle "_" --append "CAT" in.sdf -osdf | obabel -isdf -Oout.sdf --delete "CAT"
(I also changed the property name in --append to match the one in --delete, in my testing it made a difference if I used upper or lower case)

➜ obabel -:"CCC title" --gen2D -osdf --property CAT=test | obabel -isdf --addtotitle "_" --append "CAT" -osdf | obabel -
isdf -osdf --delete "CAT"
1 molecule converted
1 molecule converted
title_ test
 OpenBabel11232311102D

  3  2  0  0  0  0  0  0  0  0999 V2000
    1.7321   -0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    0.8660    0.5000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
   -0.0000   -0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
  1  2  1  0  0  0  0
  2  3  1  0  0  0  0
M  END
$$$$
1 molecule converted