How to Make my R script executable?

Question

I am aware this is at high risk of being a duplicate, but in none of the other questions here I have found an answer to my problem. Below is a summary of what I have already tried.

I have an R script file file.r:

#!/usr/bin/env Rscript 
print("Hello World!")

which is executable (chmod +x file.r), and which used to run nicely (last time I used it was about a month ago) by issuing:

$ ./file.r

However, today:

$ ./file.r
/usr/bin/env: 'Rscript\r': No such file or directory

In fact:

$ which Rscript
/usr/bin/Rscript 

Thus I changed shebang to: #!/usr/bin Rscript, but:

$ ./file.r
/usr/bin: bad interpreter: Permission denied

Then I thought I would run it as super user, but:

$ sudo ./file.r
sudo: unable to execute ./file.r: Permission denied

Reading around I found that a fresh installation of R would solve my problem, so I un-installed and installed R. Unfortunately what I have written before still applies. Notice however that the following works with both shebang versions:

$ Rscript file.r
[1] "Hello World!"

What am I doing wrong?

Solution 1

Ah, Its carriage return (\r) issue, It's added to the first line, if you are using vi editor, :set list will show it. line endings will be shown as $ and carriage return chars as ^M.

#!/usr/bin/env Rscript  Makes your script portable than #!/usr/bin/Rscript

Btw, you can insert \r in vi by going into insert(i)/Append(a) mode and type ctrl+v and then ctrl+m

Solution 2

If you want to point directly to the executable, then you need the full path after the shebang (no space):

#!/usr/bin/Rscript

As Ravi pointed out, if this fix doesn't work then the solution may just involve deleting the line break and putting it in again.

I'm not a fan of the env workaround to make things more portable, because it makes the line more confusing and most people don't realise that it's actually calling another program (i.e. env) to run the code in a modified shell. More information on that here.