In the world of programming, efficiency is key. And when it comes to running commands in Bash, there’s one trick that can save you time and effort: starting multiple chained commands in the background. This technique allows you to run multiple commands simultaneously without having to wait for each one to finish before moving on to the next. In this article, we’ll explore how to use this powerful feature and how it can streamline your workflow.
First, let’s define what we mean by “chained commands.” In Bash, a chained command is a series of commands that are connected by the use of special characters like “&&” or “|”. These characters instruct Bash to run the next command only if the previous one was successful. This allows us to create a sequence of commands that depend on each other, without having to manually check for errors.
Now, let’s dive into how to start multiple chained commands in the background. The key here is the “&” symbol, also known as the “ampersand.” When you add this symbol at the end of a command, it tells Bash to run that command in the background, freeing up your terminal for other tasks.
For example, let’s say we want to run three commands in a sequence: “ls” to list the contents of a directory, “cd” to change into a specific directory, and “pwd” to print the current working directory. Normally, we would have to wait for each command to finish before running the next one. But with the “&” symbol, we can run all three commands simultaneously by chaining them together and adding “&” at the end of each one.
Here’s how it would look:
ls && cd Desktop && pwd &
Notice how the “&” symbol is added after each command. This tells Bash to run each command in the background, freeing up our terminal for other tasks. And the best part? We can continue working in our terminal while these commands are running, without having to wait for them to finish.
But what if we want to run multiple chained commands in the background, without having to type out the “&” symbol after each one? This is where the “nohup” command comes in. Short for “no hang up,” this command allows us to run a series of commands in the background, even after we close our terminal.
To use “nohup,” we simply add it at the beginning of our command sequence and enclose the entire sequence within parentheses. Here’s an example:
nohup (ls && cd Desktop && pwd) &
Now, even if we close our terminal, these commands will continue running in the background.
But what if we want to run multiple chained commands in the background, but also want to see their output? This is where the “tee” command comes in. By using “tee,” we can redirect the output of our commands to a file, while still running them in the background.
Here’s an example:
nohup (ls && cd Desktop && pwd) | tee output.txt &
This will run our commands in the background, while also saving the output to a file called “output.txt.”
In conclusion, starting multiple chained commands in the background with Bash is a powerful technique that can save you time and effort. By using the “&” symbol, “nohup” command, and “tee” command, you can run multiple commands simultaneously, continue working in your terminal, and even save the output to a file. So the next time you find yourself running a series of commands, remember this trick and watch as it streamlines your workflow. Happy coding!
