$ which bash reveals that the bash shell is located at /bin/bash.
It's important to note that every bash shell script begins with a shebang #!, which is not treated as a comment.
The shebang specifies the interpreter for the kernel, indicating that /bin/bash should be used to execute the commands in the file.
Using #!/usr/bin/env instead of #!/bin/bash in scripts enhances portability across Unix systems. The env command, when followed by a command, runs that command in a new shell instance. While there's no guarantee that env will always be in /usr/bin/, it's a common location, making it suitable for running scripts with varied environments.
The choice of env increases portability, especially when dealing with languages like Python or NodeJS. Unlike specifying the absolute path (/bin/bash), which assumes a fixed location for bash, env searches for the command in the $PATH variable. This accommodates different system configurations where bash might be in locations like /usr/bin/ or even user-specific directories.
This approach ensures scripts can be used in diverse Unix environments, making them more versatile and reducing the risk of encountering interpreter issues due to varying bash locations.