From a8777bb375377ce0dc751ad14cc63ad194eefccb Mon Sep 17 00:00:00 2001
From: Grische <github@grische.xyz>
Date: Thu, 18 Nov 2021 16:58:33 +0100
Subject: [PATCH] Expanded on how to use lastpipe

---
 SC2031.md | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/SC2031.md b/SC2031.md
index a70380d..50c28cf 100644
--- a/SC2031.md
+++ b/SC2031.md
@@ -18,9 +18,19 @@ n=0
 while read i; do (( n+=i )); done < <(printf "%s\n" {1..10})
 echo $n
 ```
-
 In `sh`, a temp file (better if fifo or fd) can be used instead of process substitution. And if it's acceptable to do it with waiting, try Here Documents.
 
+
+With Bash 4.2+ you can also use `shopt -s lastpipe` which will change the pipe behaviour to be similar to Ksh and Zsh (see Rationale below) [as long as job control is not active](https://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html) (e.g. inside a script):
+```bash
+#!/usr/bin/env bash
+shopt -s lastpipe
+n=0
+printf "%s\n" {1..10} | while read i; do (( n+=i )); done
+echo $n
+```
+
+
 ### Rationale:
 
 Variables set in subshells are not available outside the subshell. This is a wide topic, and better described on the [Wooledge Bash Wiki](http://mywiki.wooledge.org/BashFAQ/024).
@@ -30,8 +40,8 @@ Here are some constructs that cause subshells (shellcheck may not warn about all
 Pipelines:
 
 ```sh
-subshell1 | subshell2 | subshell3    # Bash, Dash, Ash
-subshell1 | subshell2 | regular      # Ksh, Zsh
+subshell1 | subshell2 | subshell3    # Dash, Ash, Bash (default)
+subshell1 | subshell2 | regular      # Ksh, Zsh, Bash (with lastpipe=on and no job control)
 ```
 
 Command substitution: