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I installed Julia locally by unpacking it into a folder. Then I tried to add the executable to /usr/local/bin since I don't want to modify the $PATH.

sudo ln -s bin/julia-1.5.3/bin/julia /usr/local/bin/julia

If I now execute Julia in a new shell window the following message pops up:

$ julia
zsh: command not found: julia

$ ls -l /usr/local/bin/
total 12
lrwxrwxrwx 1 root root 25 Jan  1 10:08 julia -> bin/julia-1.5.3/bin/julia

So obviously the symlink exists nevertheless my shell tells me the command was not found. What is the problem here?

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    The symlink does indeed exist, but the question is, does the file that it points to exist? I.e. are you 100% sure that there actually exists an executable file at /usr/local/bin/bin/julia-1.5.3/bin/julia? Jan 1, 2021 at 20:46
  • There is information missing I guess. I executed this in my home folder so the folder is at $HOME/bin/julia. Executing this command with the working directory in home leads to the described error. I used bash completetion for the paths so I am 100% sure they were correct when I called ln.
    – matt3o
    Jan 2, 2021 at 18:05

1 Answer 1

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The solution is rather simple. Use an absolute symlink here such that the first argument of ln -s is a full path instead.

sudo ln -s /home/user/bin/julia-1.5.3/bin/julia /usr/local/bin/julia

Now it opens correctly and executes as expected.

The second and more complex solution is to use a relative symlink. However it has to be relative to the folder where the symlink will be created. Thus starting at /usr/local/bin one has to move up three folders to be at / and then descend into the appropriate folder.

sudo ln -s ../../../home/user/bin/julia-1.5.3/bin/julia /usr/local/bin/julia

Update: The comment below is correct and I edited the answer accordingly. Relative symlinks are fine and exist for good reasons however here they don't make any sense since they complicate the path a lot.

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    It doesn't always have to be absolute, it's just the reasonable thing to do in this case. Relative symlinks have their uses, or they wouldn't exist in the first place.
    – hobbs
    Jan 1, 2021 at 17:50
  • Good comment! I just now tried to understand how a solution with a relative symlink would look like and upated the answer.
    – matt3o
    Jan 3, 2021 at 11:03

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