feat: Add generate command to generate install script

assets/chezmoi.io/docs/reference/commands/generate.md

@@ -0,0 +1,13 @@
+# `generate` *file*
+
+Generates *file* for use with chezmoi. The currently supported *file*s are:
+
+| File         | Description                                                |
+| ------------ | ---------------------------------------------------------- |
+| `install.sh` | An install script, suitable for use with Github Codespaces |
+
+!!! example
+
+    ```console
+    $ chezmoi generate install.sh > install.sh
+    ```

assets/chezmoi.io/docs/user-guide/machines/containers-and-vms.md

@@ -44,47 +44,24 @@ This sets the `codespaces` template variable, so you don't have to repeat `(env
 "CODESPACES")` in your templates. It also sets the `sourceDir` configuration to
 the `--source` argument passed in `chezmoi init`.
 
-Second, create an `install.sh` script that installs chezmoi and your dotfiles:
-
-```sh
-#!/bin/sh
-
-set -e # -e: exit on error
-
-if [ ! "$(command -v chezmoi)" ]; then
-  bin_dir="$HOME/.local/bin"
-  chezmoi="$bin_dir/chezmoi"
-  if [ "$(command -v curl)" ]; then
-    sh -c "$(curl -fsLS https://chezmoi.io/get)" -- -b "$bin_dir"
-  elif [ "$(command -v wget)" ]; then
-    sh -c "$(wget -qO- https://chezmoi.io/get)" -- -b "$bin_dir"
-  else
-    echo "To install chezmoi, you must have curl or wget installed." >&2
-    exit 1
-  fi
-else
-  chezmoi=chezmoi
-fi
-
-# POSIX way to get script's dir: https://stackoverflow.com/a/29834779/12156188
-script_dir="$(cd -P -- "$(dirname -- "$(command -v -- "$0")")" && pwd -P)"
-# exec: replace current process with chezmoi init
-exec "$chezmoi" init --apply "--source=$script_dir"
+Second, create an `install.sh` script that installs chezmoi and your dotfiles
+and add it to `.chezmoiignore` and your dotfiles repo:
+
+```console
+$ chezmoi generate install.sh > install.sh
+$ chmod a+x install.sh
+$ echo install.sh >> .chezmoiignore
+$ git add install.sh .chezmoiignore
+$ git commit -m "Add install.sh"
 ```
 
-Ensure that this file is executable (`chmod a+x install.sh`), and add
-`install.sh` to your `.chezmoiignore` file.
-
-It installs the latest version of chezmoi in `~/.local/bin` if needed, and then
-`chezmoi init ...` invokes chezmoi to create its configuration file and
-initialize your dotfiles. `--apply` tells chezmoi to apply the changes
+The generated script installs the latest version of chezmoi in `~/.local/bin` if
+needed, and then `chezmoi init ...` invokes chezmoi to create its configuration
+file and initialize your dotfiles. `--apply` tells chezmoi to apply the changes
 immediately, and `--source=...` tells chezmoi where to find the cloned
 `dotfiles` repo, which in this case is the same folder in which the script is
 running from.
 
-If you do not use a chezmoi configuration file template you can use `chezmoi
-apply --source=$HOME/dotfiles` instead of `chezmoi init ...` in `install.sh`.
-
 Finally, modify any of your templates to use the `codespaces` variable if
 needed. For example, to install `vim-gtk` on Linux but not in Codespaces, your
 `run_once_install-packages.sh.tmpl` might contain:

assets/chezmoi.io/mkdocs.yml

@@ -136,6 +136,7 @@ nav:
     - encrypt: reference/commands/encrypt.md
     - execute-template: reference/commands/execute-template.md
     - forget: reference/commands/forget.md
+    - generate: reference/commands/generate.md
     - git: reference/commands/git.md
     - help: reference/commands/help.md
     - init: reference/commands/init.md

assets/templates/install.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+# -e: exit on error
+# -u: exit on unset variables
+set -eu
+
+if ! chezmoi="$(command -v chezmoi)"; then
+  bin_dir="${HOME}/.local/bin"
+  chezmoi="${bin_dir}/chezmoi"
+  echo "Installing chezmoi to '${chezmoi}'" >&2
+  if command -v curl >/dev/null; then
+    chezmoi_install_script="$(curl -fsSL https://chezmoi.io/get)"
+  elif command -v wget >/dev/null; then
+    chezmoi_install_script="$(wget -qO- https://chezmoi.io/get)"
+  else
+    echo "To install chezmoi, you must have curl or wget installed." >&2
+    exit 1
+  fi
+  sh -c "${chezmoi_install_script}" -- -b "${bin_dir}"
+  unset chezmoi_install_script bin_dir
+fi
+
+# POSIX way to get script's dir: https://stackoverflow.com/a/29834779/12156188
+script_dir="$(cd -P -- "$(dirname -- "$(command -v -- "$0")")" && pwd -P)"
+
+set -- init --apply --source="${script_dir}"
+
+echo "Running 'chezmoi $*'" >&2
+# exec: replace current process with chezmoi
+exec "$chezmoi" "$@"

assets/templates/templates.go

@@ -5,5 +5,6 @@ import "embed"
 
 // FS contains all templates.
 //
+//go:embed *.sh
 //go:embed *.tmpl
 var FS embed.FS

pkg/cmd/config.go

@@ -1396,6 +1396,7 @@ func (c *Config) newRootCmd() (*cobra.Command, error) {
 		c.newEncryptCommand(),
 		c.newExecuteTemplateCmd(),
 		c.newForgetCmd(),
+		c.newGenerateCmd(),
 		c.newGitCmd(),
 		c.newIgnoredCmd(),
 		c.newImportCmd(),

pkg/cmd/generatecmd.go

@@ -0,0 +1,45 @@
+package cmd
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"github.com/twpayne/chezmoi/v2/assets/templates"
+)
+
+func (c *Config) newGenerateCmd() *cobra.Command {
+	generateCmd := &cobra.Command{
+		Use:       "generate file",
+		Short:     "Generate a file for use with chezmoi",
+		Long:      mustLongHelp("generate"),
+		Example:   example("generate"),
+		Args:      cobra.ExactArgs(1),
+		ValidArgs: []string{"install.sh"},
+		RunE:      c.runGenerateCmd,
+		Annotations: map[string]string{
+			doesNotRequireValidConfig: "true",
+		},
+	}
+
+	return generateCmd
+}
+
+func (c *Config) runGenerateCmd(cmd *cobra.Command, args []string) error {
+	builder := strings.Builder{}
+	builder.Grow(16384)
+	switch args[0] {
+	case "install.sh":
+		data, err := templates.FS.ReadFile("install.sh")
+		if err != nil {
+			return err
+		}
+		if _, err := builder.Write(data); err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("%s: unsupported file", args[0])
+	}
+	return c.writeOutputString(builder.String())
+}

pkg/cmd/testdata/scripts/generate.txt

@@ -0,0 +1,3 @@
+# test that chezmoi generate install.sh generates a shell script
+chezmoi generate install.sh
+stdout '#!/bin/sh'