demo

#! /bin/bash

set -e

DIR='.demo-pipes'

rm -rf "$DIR"
mkdir -p "$DIR"

mem_used() {
    free -h | awk '/^Mem:/ {printf "%s / %s\n", $3, $2; exit 0}'
}

disk_rem() {
    df -h / | awk 'NR == 2 {printf "%s / %s\n", $3, $2; exit 0}'
}

loadavg() {
    cat /proc/loadavg
}

mkfifo "$DIR"/counter;      while :; do echo $((i++)) > "$DIR"/counter; sleep 1; done &
mkfifo "$DIR"/mem;          while :; do mem_used      > "$DIR"/mem;     sleep 1; done &
mkfifo "$DIR"/disk;         while :; do disk_rem      > "$DIR"/disk;    sleep 1; done &
mkfifo "$DIR"/loadavg;      while :; do loadavg       > "$DIR"/loadavg; sleep 1; done &
mkfifo "$DIR"/expire;       echo  'will expire'       > "$DIR"/expire &
mkfifo "$DIR"/error;        (echo 'will error'        > "$DIR"/error;   sleep 1; rm "$DIR"/error) &
mkfifo "$DIR"/date;         while :; do date          > "$DIR"/date;    sleep 1; done &
mkfifo "$DIR"/never-expire; echo  'never exprires'    > "$DIR"/never-expire &

./pista \
    -f '(' \
    -s ')  (' \
    -r ')' \
    -l 0 \
    "$DIR"/counter  5 2 \
    "$DIR"/mem 15 2 \
    "$DIR"/disk 15 2 \
    "$DIR"/loadavg 30 2 \
    "$DIR"/expire 15 5 \
    "$DIR"/error 15 2 \
    "$DIR"/date 31 2 \
    "$DIR"/never-expire 15 -1