What shell are you using? It looks like gdb is passing nbt as an argument to ebook-convert. Try it like this
gdb --args /opt/calibre/ebook-meta db030-473.epub --get-cover x.jpg
Then at the gdb prompt type
run
and hit enter
then after the process crashes, type
bt
and hit enter to get the backtrace.
What shell are you using? It looks like gdb is passing nbt as an argument to ebook-convert. Try it like this
gdb --args /opt/calibre/ ebook-meta db030-473.epub --get-cover x.jpg
Then at the gdb prompt type
run
and hit enter
then after the process crashes, type
bt
and hit enter to get the backtrace.