When links are put in /usr/bin or /usr/local/bin, this is often because the actual binary is living somewhere else. Why is it living somewhere else? Usually because it is a part of a group of files, often in its own subdirectory, which it depends on to run. Why can't all those files be dumped into /usr/bin or /usr/local/bin? Because those locations are only for binaries, the binaries live at the top level of those directories, and no subdirectories are allowed.
So, why don't we use a hard link there? Because a hard link to a file is considered to be of equal status to the original file (it shares the same inode) and the file will not be deleted while there is a hard link to it. In contrast, a symbolic link is simply a pointer to "the real thing". In practice, putting a hard link to a binary file that is living somewhere else wouldn't make much sense, because if those other files in that other location/subdirectory were removed, the file could not function by itself.
An example of this are the various TeX utilities, which live in /usr/bin. If you look at them, you will see that many of them point to files that are actually in /usr/share/texlive/texmf-dist/scripts/. You can see these, for example, by doing ls -la | grep texmf.
As muru mentions, another reason is that hard links don't work across filesystems.
Another situation in which links are used for files in /usr/bin or /usr/local/bin is Debian's alternatives system. In this case, a binary may be a symbolic link pointing to a symbolic link in /etc/alternatives, which then points to the actual binary, often again itself in /usr/bin.
Example:
ls -la /usr/bin/awk
lrwxrwxrwx 1 root root 21 Jul 31 2013 /usr/bin/awk -> /etc/alternatives/awk
ls -la /etc/alternatives/awk
lrwxrwxrwx 1 root root 13 Aug 11 2013 /etc/alternatives/awk -> /usr/bin/gawk
It is fairly obvious in this case that a symbolic link is the correct mechanism, because it is pointing to any of a range of possible binaries.
If you are looking for way to run/execute program/script as a command directly from terminal, then I think putting scripts or links to /usr/local/bin is good choice!
Also the advantage is that it is already in path. Visit this related post.
But if a program directory provides several executables, then I think exporting path of that directory may useful/better than creating several symlinks individually.
Best Answer
Aliases are for commands - what you need is a simple variable that references your long directory name. Add something like this to your ~/.bashrc:
Now, commands like
ls "$shortdir"ordu "$shortdir"will give you what you want.