Bash Function
Declaration
A function is declared with one of:
myfunction() {
:
}
function myfunction() {
:
}If the function keyword is used, the parentheses are optional.
Usage
The above functions would be called like:
myfunction "first argument" "second argument"
Arguments
Arguments passed to a function implicitly overwrite the positional variables ($1, $2, and so on) as well as the argument count variable ($#). All of these will be reset to the original values upon the function's return.
Note that $0 is not overwritten.
Error and Return Codes
A function does not set the exit code. But it also does not clear the code. The final command in a function effectively sets the error code for the function as well.
The return builtin causes the function to return immediately.