wait

The wait command line tool is a commonly used utility in Unix-like operating systems. It allows users to pause the execution of a script or command until certain conditions are met.

The primary purpose of the wait command is to wait for the completion of background processes launched by a script. It is often used in shell scripts to synchronize the execution of multiple tasks.

One of the main functionalities of wait is to wait for the termination of child processes. By specifying the process ID (PID) of a specific process, wait will pause the execution until that process completes.

Additionally, the wait command can be used without any arguments to wait for all child processes to finish executing before proceeding. This is useful in scenarios where multiple background tasks are spawned, and the script needs to wait until all tasks are completed.

The wait command can also be combined with other commands to form more complex expressions. For example, it can be used in combination with other condition checks to create a waiting loop until a certain condition is met.

In case a timeout is desired, the wait command can be augmented with a timeout value to ensure that the execution proceeds even if the desired condition is not met after a specific period.

Sometimes, the wait command may return an exit status that can be evaluated by the script for further decision making. It can indicate the success or failure of the waited process, enabling conditional logic based on the result.

Furthermore, the wait command can be used in conjunction with signal handling and can wait for specific signals to occur before resuming the execution. For instance, it can wait for a SIGINT signal to gracefully terminate the script.

The wait command is widely supported across different Unix-like operating systems, including Linux and macOS, making it a portable tool for scripting purposes.

Overall, wait is a versatile and handy command line tool that provides crucial synchronization and control mechanisms in scripts or command line processes.