process substitution

This article discusses Bash process substitution, highlighting the challenge of capturing stderr within it, such as in `diff &1)`. Normally, stderr directly outputs to the terminal, but using redirection (`2>&1`), stderr can be merged with stdout for comprehensive command comparisons, crucial for debugging and automation in scripting. Examples demonstrate how to manage output streams effectively in Bash scripts.

In Linux Bash scripting, using subshells inside loops can decrease performance due to the high resource usage of spawning new subshells in each iteration. Process substitution, which uses `(commands)`, serves as an efficient alternative, allowing direct interaction with processes as if dealing with files. This method enhances script efficiency, especially when handling large datasets or in extensive loops, avoiding the overhead brought by subshells and improving execution speed.