read stdin in function in bash script

Question

If the question is How do I pass stdin to a bash function?, then the answer is:

Shellscript functions take stdin the ordinary way, as if they were commands or programs. 🙂

input.txt:

HELLO WORLD
HELLO BOB
NO MATCH

test.sh:

#!/bin/sh

myfunction() {
    grep HELLO
}

cat input.txt | myfunction

Output:

hobbes@metalbaby:~/scratch$ ./test.sh 
 HELLO WORLD 
 HELLO BOB

Note that command line arguments are ALSO handled in the ordinary way, like this:

test2.sh:

#!/bin/sh

myfunction() {
    grep "$1"
}

cat input.txt | myfunction BOB

Output:

hobbes@metalbaby:~/scratch/$ ./test2.sh 
 HELLO BOB