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Use the powerful 'Bash wait' command to optimize shell programs. Synchronize background processes to enable orderly execution and error reduction. Tasks may be easily streamlined.
In the world of shell scripting, process management and synchronization are critical. The Bash wait command is a quick and easy way to coordinate and regulate the execution flow of several processes. Understanding how to use the wait command correctly can improve the efficiency and dependability of your shell scripts greatly. In this article, we will deconstruct the Bash wait command, looking at its features, typical use cases, and best practices in Linux.
Table of Contents
Access to the command line/terminal.
Administrator (sudo) privileges.
A text editor, such as Vim or Nano.
Syntax for Bash wait command
Waits for a child process to terminate.
wait [-n] job_id
Waits for the job with the specified job_id to terminate. The -n option causes wait to return immediately if the job is already terminated.
Waits for the next background job to terminate.
Bash wait Command Syntax
When working with wait in bash scripts, there are three more parameters to be aware of:
The ampersand sign (&) following a command denotes a background job.
$! returns the PID of the most recent background process. When working with several background processes, remember to save the previous PID in a variable.
$? displays the last process’s exit status.
To show how these three factors interact, launch a terminal window and type:
The terminal prints the Done message after 10 seconds (due to sleep 10).
Single Process Bash wait
Use the wait command to specify when a background process within a script must execute.
For example, in a text editor, enter the following code:
echo Background process &
echo First message
echo Second message
echo Third message
If the background process does not complete the first and second processes, the wait command causes a pause to wait for the background process to finish the second process before proceeding to the third process.
Save the script as single_process.sh. Change the permissions in the terminal to make the script executable:
sudo chmod +x single_process.sh
Use the following commands to run the script:
The background process finishes once the wait instruction is executed, and the script proceeds.
Multiple Processes Bash Wait
Open a text editor and paste the following script with several processes:
Finally, the Bash wait command proved to be an indispensable tool for managing process synchronization in shell scripts. It ensures orderly execution and reduces errors by halting execution until defined procedures are completed. Incorporating the wait command into your scripts enables you to enhance efficiency and effectively control concurrent processes. Please feel free to share your thoughts and feedback in the comment section below.
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