I installed the xournal tazpkg, and it appears to be broken. The executable file is missing from the package. There may be other missing files as well.
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root@tablet:~# tazpkg list-files xournal
Installed files with: xournal
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/usr/share/applications/xournal.desktop
/usr/share/icons/hicolor/scalable/apps/xournal.svg
/usr/share/icons/hicolor/scalable/mimetypes/gnome-mime-application-x-xoj.svg
/usr/share/icons/hicolor/scalable/mimetypes/xoj.svg
/usr/share/mimelnk/application/x-xoj.desktop
/usr/share/mime/packages/xournal.xml
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6 files installed with xournal.
root@tablet:~# xournal
sh: xournal: not found