diff --git a/Makefile b/Makefile
index 8db16bb..dd078c4 100644
--- a/Makefile
+++ b/Makefile
@@ -60,7 +60,7 @@ pkg-clean:
 
 pkg-build:
 	@: $${L} $${T}
-	cd $(BUILD)/src && pkg="$(PWD)/$(BUILD)/pkg" $(or $(CMD),../build.bash)
+	cd $(BUILD)/src && pkg="$(PWD)/$(BUILD)/pkg" src="$(PWD)/$(BUILD)/src" $(or $(CMD),../build.bash)
 
 pkg-debug:
 	@: $${L} $${T}
@@ -148,7 +148,8 @@ test:
 	node backend/test-runner.js $(F)
 
 sandbox:
-	node backend/sandbox.js
+	@: $${L}
+	L=$(L) node backend/sandbox.js
 
 ### Fetch artifacts from registries
 
diff --git a/backend/sandbox.bash b/backend/sandbox.bash
new file mode 100644
index 0000000..051216f
--- /dev/null
+++ b/backend/sandbox.bash
@@ -0,0 +1,61 @@
+# This script is sourced by Bash within 'make sandbox'.
+
+if [[ -z "$L" ]]; then
+    echo 'environment variable unset: $L' >&2
+    exit 1
+fi
+
+cfg="$(< "/opt/riju/langs/$L.json")" || exit 1
+
+function get {
+    jq -r ".$1" <<< "${cfg}"
+}
+
+function has {
+    get "$@" | grep -vq '^null$'
+}
+
+function daemon {
+    has daemon && eval "$(get daemon)"
+}
+
+function setup {
+    has setup && eval "$(get setup)"
+}
+
+function repl {
+    has repl && eval "$(get repl)"
+}
+
+function main {
+    : > "$(get main)"
+    has prefix && get prefix >> "$(get main)"
+    get template >> "$(get main)"
+    has suffix && get suffix >> "$(get main)"
+}
+
+function compile {
+    has compile && echo "$(get compile)" && eval "$(get compile)"
+}
+
+function run-only {
+    has run && echo "$(get run)" && eval "$(get run)"
+}
+
+function run {
+    compile && run-only
+}
+
+function format {
+    has format && echo "$(get format.run)" && eval "( $(get format.run) ) < $(get main)"
+}
+
+function lsp {
+    has lsp.setup && echo "$(get lsp.setup)" && eval "$(get lsp.setup)"
+    has lsp && echo "$(get lsp.start)" && eval "$(get lsp.start)"
+}
+
+if [[ -z "$NS" ]]; then
+    main
+    setup
+fi
diff --git a/backend/sandbox.js b/backend/sandbox.js
index 30a7e25..4dddd9b 100644
--- a/backend/sandbox.js
+++ b/backend/sandbox.js
@@ -1,6 +1,8 @@
 import { spawn } from "child_process";
 import { promises as fs } from "fs";
+import process from "process";
 
+import { quote } from "shell-quote";
 import { v4 as getUUID } from "uuid";
 
 import { borrowUser } from "./users.js";
@@ -21,10 +23,19 @@ function log(msg) {
 }
 
 async function main() {
+  const sandboxScript = await fs.readFile("backend/sandbox.bash", "utf-8");
+  const lang = process.env.L;
+  if (!lang) {
+    die("environment variable unset: $L");
+  }
   const uuid = getUUID();
   const { uid, returnUser } = await borrowUser(log);
   await run(privilegedSetup({ uid, uuid }), log);
-  const args = privilegedSpawn({ uid, uuid }, ["bash"]);
+  const args = privilegedSpawn({ uid, uuid }, [
+    "bash",
+    "-c",
+    `exec env L='${lang}' bash --rcfile <(cat <<< ${quote([sandboxScript])})`,
+  ]);
   const proc = spawn(args[0], args.slice(1), {
     stdio: "inherit",
   });
diff --git a/backend/users.js b/backend/users.js
index 1abc66e..2f9af6f 100644
--- a/backend/users.js
+++ b/backend/users.js
@@ -37,10 +37,19 @@ async function getCreatedUsers() {
 }
 
 async function getActiveUsers() {
+  let dirents;
+  try {
+    dirents = await fs.readdir("/tmp/riju");
+  } catch (err) {
+    if (err.code === "ENOENT") {
+      return new Set();
+    }
+    throw err;
+  }
   return new Set(
     (
       await Promise.all(
-        (await fs.readdir("/tmp/riju"))
+        dirents
           .filter((name) => name.match(uuidRegexp))
           .map((name) => fs.stat(`/tmp/riju/${name}`))
       )
diff --git a/docker/packaging/install.bash b/docker/packaging/install.bash
index 2f11083..13d1357 100755
--- a/docker/packaging/install.bash
+++ b/docker/packaging/install.bash
@@ -34,6 +34,7 @@ ripgrep
 sudo
 tmux
 unzip
+vim
 wget
 yarn
 
diff --git a/deps/prettier.yaml b/shared/prettier.yaml
similarity index 100%
rename from deps/prettier.yaml
rename to shared/prettier.yaml
diff --git a/deps/sass.yaml b/shared/sass.yaml
similarity index 100%
rename from deps/sass.yaml
rename to shared/sass.yaml
diff --git a/tools/config.js b/tools/config.js
index 9f562fc..7eca441 100644
--- a/tools/config.js
+++ b/tools/config.js
@@ -20,6 +20,14 @@ export async function getLangs() {
     .map((lang) => path.parse(lang).name);
 }
 
+// Return a list of the IDs of all the configured shared dependencies.
+// Each such ID can be passed to readSharedDepConfig.
+export async function getSharedDeps() {
+  return (await fs.readdir("shared"))
+    .filter((lang) => lang.endsWith(".yaml"))
+    .map((lang) => path.parse(lang).name);
+}
+
 // Return a list of objects representing the packages to be built. See
 // the function implementation for the full list of keys.
 export async function getPackages() {
@@ -36,6 +44,17 @@ export async function getPackages() {
       });
     }
   }
+  for (const dep of await getSharedDeps()) {
+    const type = "shared";
+    const name = `riju-${type}-${lang}`;
+    packages.push({
+      lang,
+      type,
+      name,
+      buildScriptPath: `build/${type}/${lang}/build.bash`,
+      debPath: `build/${type}/${lang}/${name}.deb`,
+    });
+  }
   return packages;
 }
 
@@ -71,3 +90,17 @@ export async function readLangConfig(lang) {
   }
   return fixupLangConfig(langConfig);
 }
+
+// Read the YAML config file for the shared dependency with the given
+// string ID and return it as an object.
+export async function readSharedDepConfig(lang) {
+  const langConfig = YAML.parse(
+    await fs.readFile(`shared/${lang}.yaml`, "utf-8")
+  );
+  if (langConfig.id !== lang) {
+    throw new Error(
+      `shared dependency config id ${langConfig.id} doesn't match expected ${lang}`
+    );
+  }
+  return fixupLangConfig(langConfig);
+}
diff --git a/tools/generate-build-script.js b/tools/generate-build-script.js
index 39db38e..5c05e36 100644
--- a/tools/generate-build-script.js
+++ b/tools/generate-build-script.js
@@ -3,18 +3,22 @@ import process from "process";
 import { Command } from "commander";
 import YAML from "yaml";
 
-import { readLangConfig } from "./config.js";
+import { readLangConfig, readSharedDepConfig } from "./config.js";
 
 // Given a language config object, return the text of a Bash script
 // that will build the (unpacked) riju-lang-foo Debian package into
 // ${pkg} when run in an appropriate environment. This is a package
 // that will install the language interpreter/compiler and associated
 // tools.
-function makeLangScript(langConfig) {
+//
+// isShared (optional) truthy means to generate a shared dependency
+// package riju-shared-foo rather than a language installation
+// package.
+function makeLangScript(langConfig, isShared) {
   const {
     id,
     name,
-    install: { prepare, apt, pip, manual, deb },
+    install: { prepare, apt, riju, pip, manual, deb },
   } = langConfig;
   let parts = [];
   parts.push(`\
@@ -45,6 +49,9 @@ sudo apt-get install -y ${apt.join(" ")}`);
   if (apt) {
     depends = depends.concat(apt);
   }
+  if (riju) {
+    depends = depends.concat(riju.map((name) => `riju-shared-${name}`));
+  }
   if (deb) {
     depends = depends.concat(
       deb.map((fname) => `\$(dpkg-deb -f "${fname}" Depends)`)
@@ -52,11 +59,13 @@ sudo apt-get install -y ${apt.join(" ")}`);
   }
   parts.push(`depends=(${depends.map((dep) => `"${dep}"`).join(" ")})`);
   let debianControlData = `\
-Package: riju-lang-${id}
+Package: riju-${isShared ? "shared" : "lang"}-${id}
 Version: \$(date +%s%3N)
 Architecture: amd64
 Maintainer: Radon Rosborough <radon.neon@gmail.com>
-Description: The ${name} language packaged for Riju
+Description: The ${name} ${
+    isShared ? "shared dependency" : "language"
+  } packaged for Riju
 Depends: \$(IFS=,; echo "\${depends[*]}")
 Riju-Script-Hash: \$(sha1sum "\$0" | awk '{ print \$1 }')`;
   parts.push(`\
@@ -107,7 +116,7 @@ EOF`);
 // that installs tools used by multiple languages, and can be declared
 // as a dependency.
 function makeSharedScript(langConfig) {
-  throw new Error("shared script generation not implemented yet");
+  return makeLangScript(langConfig, true);
 }
 
 // Parse command-line arguments, run main functionality, and exit.
@@ -129,7 +138,13 @@ async function main() {
     console.error(`make-script.js: unsupported --type ${program.type}`);
     process.exit(1);
   }
-  console.log(scriptMaker(await readLangConfig(program.lang)));
+  console.log(
+    scriptMaker(
+      program.type === "shared"
+        ? await readSharedDepConfig(program.lang)
+        : await readLangConfig(program.lang)
+    )
+  );
   process.exit(0);
 }