When you use new Linux, use the terminal bash command "split" is faster and the best! Lxsplit is not fast as the default already have terminal bash command "split", Linux version of Hjsplit is unable to use, some other split file programs require Java, I searched for many split file programs! Run "split -b 100m filetosplit" to split big filetosplit to many 100m x?? files, run "split --help" and search for split command help! Run "cat `ls x??` > filetomerge" to merge into filetomerge, run "cat --help"! No others is better than "split"!
Excellent to merge (append) many files into one. No need for GUI, because it can be used from within File Manager by adding a custom action. In Linux Mint Xfce's Thunar, use syntax "lxsplit -j %f" for all types of files matching *.001.