I'm trying to speed up some Bash scripts that process different file types. Could anyone share some examples of how parallel processing works in Bash? I'd love to see practical implementations to understand better how to structure my commands for parallel execution.
2 Answers
You can define a function like this:
```bash
#! /bin/bash
function doStuff() {
someCommand "$1"
}
export -f doStuff
find /where/ever -maxdepth 1 -type f -name '*.txt' | parallel -j 32 doStuff {}
```
This runs `doStuff` in parallel for all the `.txt` files found, utilizing up to 32 jobs at once.
Parallel processing is all about handling multiple commands simultaneously. You can run commands in the background using `&`, which keeps them out of the terminal and allows for ongoing execution. Remember to use `wait` to ensure the script waits for these background processes to complete before moving on.
For instance:
```bash
your_command &
pid1=$!
your_command &
pid2=$!
wait $pid1 $pid2
```
This way, your script will wait for the background processes to finish before continuing.
Just keep in mind that you should avoid relying on output from the background processes, as this can complicate things if you're not capturing it properly.