atomic create file if not exists from bash script

Question

In system call open(), if I open with O_CREAT | O_EXCL, the system call ensures that the file will only be created if it does not exist. The atomic

Answer 1

You could create it under a randomly-generated name, then rename (mv -n random desired) it into place with the desired name. The rename will fail if the file already exists.

Like this:

#!/bin/bash

touch randomFileName
mv -n randomFileName lockFile

if [ -e randomFileName ] ; then
    echo "Failed to acquired lock"
else
    echo "Acquired lock"
fi