read stdin in function in bash script

Question

I have some set of bash functions which output some information:

• find-modelname-in-epson-ppds
• find-modelname-in-samsung-ppds
• find-modelname-in-hp-ppds
• etc ...

I've been writing functions which read output and filter it:

function filter-epson {     find-modelname-in-epson-ppds | sed <bla-blah-blah> }  function filter-hp {     find-modelname-in-hp-ppds | sed <the same bla-blah-blah> } etc ... 

But the I thought that it would be better do something like this:

function filter-general {     (somehow get input) | sed <bla-blah-blah> } 

and then call in another high-level functions:

function high-level-func {     # outputs filtered information     find-modelname-in-hp/epson/...-ppds | filter-general  } 

How can I achieve that with the best bash practices?

Answer 1

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  

Answer 2

To be painfully explicit that I'm piping from stdin, I sometimes write

cat - | ...