sudo: unable to execute ./script.sh: no such file or directory

This usually happens when the shebang (#!) line in your script is broken.

The shebang is what tells the kernel the file needs to be executed using an interpreter. When run without sudo, the message is a little more meaningful. But with sudo you get the message you got.

For example:

$ cat test.sh
#!/bin/foo
echo bar

$ ./test.sh
bash: ./test.sh: /bin/foo: bad interpreter: No such file or directory

$ bash test.sh
bar

$ sudo ./test.sh
sudo: unable to execute ./test.sh: No such file or directory

$ sudo bash ./test.sh
bar

The bad interpreter message clearly indicates that it's the shebang which is faulty.

I just had this exact problem, it turned out to be a text file encoding problem. For me to fix it while running Xubuntu 14.04.3 LTS, I installed dos2unix and converted the script's encoding and then ran the script again using sudo and it worked fine. You can find an example below:

sudo apt-get install dos2unix -y
dos2unix test.sh
sudo chmod u+x test.sh && sudo ./test.sh