Linux Process Substitution
Linux Process Substitution is a feature that allows the output of a command or process to be used as input to another command or process. This can be useful when working with commands that do not accept standard input or when you want to manipulate the output of a command before passing it on as input to another command.
Process substitution is performed using the <() or >() operators. The <() operator is used to pass the output of a command or process as standard input to another command, while the >() operator is used to pass the output of a command or process as a file to another command.
Here is an example of using process substitution to sort the output of the ls command and pass it as input to the wc command, which counts the number of lines, words, and characters in a file:
In this example, the output of the ls command is passed as input to the sort command, which sorts the output alphabetically. The sorted output is then passed as standard input to the wc command, which counts the number of lines in the input.
Process substitution can be used with any command that accepts standard input or a file as an argument. It is a powerful tool that can greatly simplify and streamline your workflow when working with the command line.
There are a few things to keep in mind when using process substitution:
Process substitution is performed asynchronously, which means that the commands or processes inside the <() or >() operators are executed in parallel with the rest of the script. This can be useful for running long-running commands or processes in the background, but it can also lead to unexpected behavior if the commands inside the process substitution depend on each other.
Process substitution is not supported by all shells. It is supported by the Bash shell and some other shells, but it may not work in all shells.
The output of a command or process passed as input to another command using process substitution is treated as a file. This means that the commands inside the process substitution must produce output that is suitable for use as a file. For example, the output must be plain text, and it should not contain any special characters that would cause problems when interpreted as part of a filename.
Process substitution can be nested, which means that you can use the output of one process substitution as input to another process substitution. This can be useful for chaining together multiple commands or processes in a complex workflow.
Overall, process substitution is a useful feature that can help you streamline your workflow and simplify complex command lines by allowing you to pass the output of one command or process as input to another. It is a powerful tool that is worth learning and using if you work with the command line on a regular basis.
Example
P.S. The above was generated by ChatGPT.
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