Ubuntu – How to create a soft or symbolic link

EDIT: the solution below does not work. It is apparent that the symbolic link is broken, because file -L cannot open the symbolic link /usr/bin/bla. In this case, do the following:

sudo ln -sf /opt/bladir/bla /usr/bin/bla

using full paths (-f is to force overwriting the previous symbolic link, if there is one).

Hm. I think that the program "bla" may be looking for things that are installed in /opt/bladir and cannot find them. For example, it can be a shell script wrapper around a Java executable, with path relative to current directory: but your current directory is /usr/bin/, and not /opt/bladir/.

If the following works

file -L /usr/bin/bla

...then it is definitely not a problem with your symbolic link.

Check whether "bla" is a shell script that you can modify, take a look inside -- maybe you will find the problem. Possibly, adding /opt/bladir to your PATH would be a better solution.

The dir1/ln2dir21 symbolic link you created is relative to dir1.

The correct command would be:

ln -s ../dir2/dir21 dir1/ln2dir21

As another test, if you go to dir1 and create dir2/dir21 you will see that the red indicator will go away:

cd dir1
mkdir -p dir2/dir21
ll

You will see ln2dir21 -> dir2/dir21/ in normal color (no red error color).