If you use the exec command in the NDS window then
you might have to wait extremely long:
number of species *
execution time of the command
(5000 species, 1.5 sec/exec) -> 2 hour waiting.
WHAT TO DO
The only way the to remove the exec command is:
run arb_panic on any shell
save the database to /tmp/panic.arb
edit /tmp/panic.arb
search the exec command
replace it by the 'echo' command
save file
test it with 'arb /tmp/panic.arb'
If everything works fine save it in your home directory
enter 'arb_clean' on any shell
remove /tmp/panic.arb
WARNINGS
Test your database very carefully because it may not be
consistent.
Check sequence checksum