Concurrent execution units within a shell script are referred to as threads in the context of shell scripting. However, unlike some other programming languages, traditional Unix-like shells (such as Bash) do not natively support multithreading within a script.
Typically, in a shell script: Each line of a script or command is carried out in turn. Background execution or subshells can spawn subprocesses, but these are not true threads and run independently. You can employ the following methods for parallel or concurrent execution.
Background Performing: Using the & operator, you can run commands or scripts in the background so that they run concurrently with the main script.
Subshells: Subshells, distinct instances of the shell, are where commands can be executed. These, however, don't function as threads and operate separately. You might think about using other languages like Python, which have strong threading support, for true multithreading and parallelism in a shell-like environment. For instance, you can create and manage threads for concurrent execution within a script using Python's threading module.