diff --git a/.github/styles/Vocab/Base/accept.txt b/.github/styles/Vocab/Base/accept.txt
index f298995..1824724 100644
--- a/.github/styles/Vocab/Base/accept.txt
+++ b/.github/styles/Vocab/Base/accept.txt
@@ -1 +1,3 @@
+Matveev
 Rabkin
+Sergey
diff --git a/.gitignore b/.gitignore
index 11789db..8736575 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,7 @@
 .github/styles/proselint
 .github/styles/Readability
 .github/styles/write-good
+.redo
+1
+clean
+lint
diff --git a/README.adoc b/README.adoc
index a67c405..9c5ca54 100644
--- a/README.adoc
+++ b/README.adoc
@@ -62,6 +62,14 @@ git clone git@github.com:rdavid/toolbox.git &&
   ./toolbox/app/install
 ----
 
+== Test
+
+The project uses Daniel J. Bernstein's build system {url-redo}[`redo`].
+You can install Sergey Matveev's {url-goredo}[`goredo`] implementation.
+`redo lint` applies the following linters to the source files:
+{url-shellcheck}[`shellcheck`], {url-shfmt}[`shfmt`], {url-typos}[`typos`],
+{url-vale}[`vale`], {url-yamllint}[`yamllint`].
+
 == License
 
 `toolbox` is copyright {url-cv}[David Rabkin] and available under a
diff --git a/all.do b/all.do
new file mode 100644
index 0000000..f63a548
--- /dev/null
+++ b/all.do
@@ -0,0 +1,4 @@
+# shellcheck shell=sh
+# vi:et lbr noet sw=2 ts=2 tw=79 wrap
+# Copyright 2024 David Rabkin
+redo-ifchange lint
diff --git a/clean.do b/clean.do
new file mode 100644
index 0000000..22dd31c
--- /dev/null
+++ b/clean.do
@@ -0,0 +1,4 @@
+# shellcheck shell=sh
+# vi:et lbr noet sw=2 ts=2 tw=79 wrap
+# Copyright 2024 David Rabkin
+rm -f 1 clean lint
diff --git a/lint.do b/lint.do
new file mode 100644
index 0000000..81e42fd
--- /dev/null
+++ b/lint.do
@@ -0,0 +1,35 @@
+# shellcheck shell=sh
+# vi:et lbr noet sw=2 ts=2 tw=79 wrap
+# Copyright 2024 David Rabkin
+redo-ifchange \
+	./*.do \
+	.github/*.yml \
+	.github/workflows/*.yml \
+	app/* \
+	README.adoc
+
+# shellcheck disable=SC2034 # Variable appears unused.
+readonly \
+	BASE_APP_VERSION=0.9.20240106 \
+	BASE_MIN_VERSION=0.9.20231212 \
+	BSH=/usr/local/bin/base.sh
+[ -r "$BSH" ] || {
+	printf >&2 Install\ Shellbase.\\n
+	exit 1
+}
+set -- "$@" --quiet
+
+# shellcheck disable=SC1090 # File not following.
+. "$BSH"
+cmd_exists shellcheck &&
+	find app -name "*" ! -path app ! -name pass -exec shellcheck {} +
+cmd_exists shfmt && {
+	shfmt -d ./*.do
+	find app -name "*" ! -path app ! -name pass -exec shfmt -d {} +
+}
+cmd_exists typos && typos
+cmd_exists vale && {
+	vale sync >/dev/null 2>&1 || :
+	vale README.adoc
+}
+cmd_exists yamllint && yamllint .github/*.yml .github/workflows/*.yml