Pipelines - Bash Execution Replay

A pipeline sends stdout from one command into stdin of the next. Each command does one small job.

Program

Play the script to see generated log text flow into grep.

pipelines.sh

#!/usr/bin/env bash

log=$'error\nok\nerror'
matches="$(printf '%s\n' "$log" | grep -c error)"
echo "matches=$matches"

pipeline `cmd1 | cmd2` connects the first command's stdout to the second command's stdin.

filter A filter reads input, selects or transforms it, and writes a result.