📺 https://youtu.be/7asa2lTcwKI
A filter (in UNIX/Linux parlance) is a command that accepts standard input with the intent to transform or “filter” the incoming lines or buffer. Modular, composable, filters are the UNIX way, not plugins. Learning to use filters in pipelines and from within Ed/Vi/m are critical UNIX/Linux scripting skills and require a good understanding of the UNIX philosophy.
Filters are superior to other plugin approaches because they so easily attach together into pipelines.
#!/bin/sh
while IFS= read -r line; do
echo "${1-#}" $line
done
myfunc() {
_filter "$@" && return $?
echo "${1-#}" "$*"
}
_filter(){
[[ -n "$1" ]] && return 1
while IFS= read -ra args; do
"${FUNCNAME[1]}" "${args[@]}"
done
}
_buffer() {
[[ -n "$1" ]] && return 1
"${FUNCNAME[1]}" "$(</dev/stdin)"
}