Have to type "yes" to install packages every time

[japanoise]

A typical invocation of org2txt looks like this for me:

$ org2txt my-org-file.org                                                                                                                                                                                        
This is org2txt, version: 20200201.1615.
Launching /usr/bin/emacs...
Emacs 26.3 (gnu/linux)
Loading /home/chameleon/builds/orgmk/site-lisp/orgmk.el...
Current value of ‘shell-file-name’: /usr/bin/zsh
... changed to: bash
Install package `htmlize'? (yes or no) yes
Setting ‘package-selected-packages’ temporarily since "emacs -q" would overwrite customizations
Setting ‘package-selected-packages’ temporarily since "emacs -q" would overwrite customizations
Install package `ox-gfm`? (yes or no) yes
Setting ‘package-selected-packages’ temporarily since "emacs -q" would overwrite customizations
Org mode version 9.1.9 (org @ /usr/share/emacs/26.3/lisp/org/)
LaTeX command: ("pdflatex -interaction=nonstopmode -output-directory=%o %f" "pdflatex -interaction=nonstopmode -output-directory=%o %f" "pdflatex -interaction=nonstopmode -output-directory=%o %f")
Loading /home/chameleon/builds/orgmk/lisp/org-latex-classes.el (source)...
Convergence after 1 iterations

I have to say yes to htmlize and ox-gfm every time; is there any way short of always typing yes yes | org2txt to automatically yes these questions? Perhaps to pre-install them?