nix env shell: Move from nix shell, add shorthand alias

doc/manual/rl-next/nix-env-shell.md

@@ -0,0 +1,12 @@
+---
+synopsis: "`nix env shell` is the new `nix shell`, and `nix shell` remains an accepted alias"
+issues: 10504
+prs: 10807
+---
+
+This is part of an effort to bring more structure to the CLI subcommands.
+
+`nix env` will be about the process environment.
+Future commands may include `nix env run` and `nix env print-env`.
+
+It is also somewhat analogous to the [planned](https://github.com/NixOS/nix/issues/10504) `nix dev shell` (currently `nix develop`), which is less about environment variables, and more about running a development shell, which is a more powerful command, but also requires more setup.

src/nix/env.cc

@@ -0,0 +1,98 @@
+#include "command.hh"
+#include "run.hh"
+#include <queue>
+
+using namespace nix;
+
+struct CmdEnv : NixMultiCommand
+{
+    CmdEnv() : NixMultiCommand("env", RegisterCommand::getCommandsFor({"env"}))
+    { }
+
+    std::string description() override
+    {
+        return "manipulate the process environment";
+    }
+
+    Category category() override { return catUtility; }
+};
+
+static auto rCmdEnv = registerCommand<CmdEnv>("env");
+
+struct CmdShell : InstallablesCommand, MixEnvironment
+{
+
+    using InstallablesCommand::run;
+
+    std::vector<std::string> command = { getEnv("SHELL").value_or("bash") };
+
+    CmdShell()
+    {
+        addFlag({
+            .longName = "command",
+            .shortName = 'c',
+            .description = "Command and arguments to be executed, defaulting to `$SHELL`",
+            .labels = {"command", "args"},
+            .handler = {[&](std::vector<std::string> ss) {
+                if (ss.empty()) throw UsageError("--command requires at least one argument");
+                command = ss;
+            }}
+        });
+    }
+
+    std::string description() override
+    {
+        return "run a shell in which the specified packages are available";
+    }
+
+    std::string doc() override
+    {
+        return
+          #include "shell.md"
+          ;
+    }
+
+    void run(ref<Store> store, Installables && installables) override
+    {
+        auto outPaths = Installable::toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, installables);
+
+        auto accessor = store->getFSAccessor();
+
+        std::unordered_set<StorePath> done;
+        std::queue<StorePath> todo;
+        for (auto & path : outPaths) todo.push(path);
+
+        setEnviron();
+
+        std::vector<std::string> pathAdditions;
+
+        while (!todo.empty()) {
+            auto path = todo.front();
+            todo.pop();
+            if (!done.insert(path).second) continue;
+
+            if (true)
+                pathAdditions.push_back(store->printStorePath(path) + "/bin");
+
+            auto propPath = accessor->resolveSymlinks(
+                CanonPath(store->printStorePath(path)) / "nix-support" / "propagated-user-env-packages");
+            if (auto st = accessor->maybeLstat(propPath); st && st->type == SourceAccessor::tRegular) {
+                for (auto & p : tokenizeString<Paths>(accessor->readFile(propPath)))
+                    todo.push(store->parseStorePath(p));
+            }
+        }
+
+        auto unixPath = tokenizeString<Strings>(getEnv("PATH").value_or(""), ":");
+        unixPath.insert(unixPath.begin(), pathAdditions.begin(), pathAdditions.end());
+        auto unixPathString = concatStringsSep(":", unixPath);
+        setEnv("PATH", unixPathString.c_str());
+
+        Strings args;
+        for (auto & arg : command) args.push_back(arg);
+
+        runProgramInStore(store, UseLookupPath::Use, *command.begin(), args);
+    }
+};
+
+static auto rCmdShell = registerCommand2<CmdShell>({"env", "shell"});
+

src/nix/main.cc

@@ -163,6 +163,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
         {"optimise-store", { AliasStatus::Deprecated, {"store", "optimise"}}},
         {"ping-store", { AliasStatus::Deprecated, {"store", "ping"}}},
         {"sign-paths", { AliasStatus::Deprecated, {"store", "sign"}}},
+        {"shell", { AliasStatus::AcceptedShorthand, {"env", "shell"}}},
         {"show-derivation", { AliasStatus::Deprecated, {"derivation", "show"}}},
         {"show-config", { AliasStatus::Deprecated, {"config", "show"}}},
         {"to-base16", { AliasStatus::Deprecated, {"hash", "to-base16"}}},

src/nix/run.cc

@@ -71,83 +71,6 @@ void runProgramInStore(ref<Store> store,
 
 }
 
-struct CmdShell : InstallablesCommand, MixEnvironment
-{
-
-    using InstallablesCommand::run;
-
-    std::vector<std::string> command = { getEnv("SHELL").value_or("bash") };
-
-    CmdShell()
-    {
-        addFlag({
-            .longName = "command",
-            .shortName = 'c',
-            .description = "Command and arguments to be executed, defaulting to `$SHELL`",
-            .labels = {"command", "args"},
-            .handler = {[&](std::vector<std::string> ss) {
-                if (ss.empty()) throw UsageError("--command requires at least one argument");
-                command = ss;
-            }}
-        });
-    }
-
-    std::string description() override
-    {
-        return "run a shell in which the specified packages are available";
-    }
-
-    std::string doc() override
-    {
-        return
-          #include "shell.md"
-          ;
-    }
-
-    void run(ref<Store> store, Installables && installables) override
-    {
-        auto outPaths = Installable::toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, installables);
-
-        auto accessor = store->getFSAccessor();
-
-        std::unordered_set<StorePath> done;
-        std::queue<StorePath> todo;
-        for (auto & path : outPaths) todo.push(path);
-
-        setEnviron();
-
-        std::vector<std::string> pathAdditions;
-
-        while (!todo.empty()) {
-            auto path = todo.front();
-            todo.pop();
-            if (!done.insert(path).second) continue;
-
-            if (true)
-                pathAdditions.push_back(store->printStorePath(path) + "/bin");
-
-            auto propPath = accessor->resolveSymlinks(
-                CanonPath(store->printStorePath(path)) / "nix-support" / "propagated-user-env-packages");
-            if (auto st = accessor->maybeLstat(propPath); st && st->type == SourceAccessor::tRegular) {
-                for (auto & p : tokenizeString<Paths>(accessor->readFile(propPath)))
-                    todo.push(store->parseStorePath(p));
-            }
-        }
-
-        auto unixPath = tokenizeString<Strings>(getEnv("PATH").value_or(""), ":");
-        unixPath.insert(unixPath.begin(), pathAdditions.begin(), pathAdditions.end());
-        auto unixPathString = concatStringsSep(":", unixPath);
-        setEnv("PATH", unixPathString.c_str());
-
-        Strings args;
-        for (auto & arg : command) args.push_back(arg);
-
-        runProgramInStore(store, UseLookupPath::Use, *command.begin(), args);
-    }
-};
-
-static auto rCmdShell = registerCommand<CmdShell>("shell");
-
 struct CmdRun : InstallableValueCommand
 {
     using InstallableCommand::run;

tests/functional/shell.sh

@@ -5,6 +5,9 @@ source common.sh
 clearStore
 clearCache
 
+# nix shell is an alias for nix env shell. We'll use the shorter form in the rest of the test.
+nix env shell -f shell-hello.nix hello -c hello | grep 'Hello World'
+
 nix shell -f shell-hello.nix hello -c hello | grep 'Hello World'
 nix shell -f shell-hello.nix hello -c hello NixOS | grep 'Hello NixOS'