diff --git a/main.go b/main.go
index 56b8d7d..babc45f 100644
--- a/main.go
+++ b/main.go
@@ -2,10 +2,6 @@ package main
 
 import (
 	"fmt"
-	"os"
-	"os/exec"
-	"strings"
-	"text/template"
 )
 
 var tmpl = `
@@ -18,39 +14,11 @@ params:
     default: "ledger.j"
 ---
 Hello this is the text:
-{{ sh "hledger bal assets" }}
+Start from {{ .from }}
+{{ sh "hledger bal assets -b $from" }}
 `
 
-func sh(command string) string {
-	args := strings.Split(command, " ")
-	out, err := exec.Command(args[0], args[1:]...).Output()
-	if err != nil {
-		return fmt.Sprintf("> Failed to execute the command:\n> %s\n", err.Error())
-	}
-	return fmt.Sprintf("\n```\n%s\n```\n", string(out))
-}
-
-func parseDocument(doc string) (frontmatter string, body string, err error) {
-	doc = strings.TrimLeft(doc, " \n")
-	sep := "---\n"
-	if !strings.HasPrefix(doc, sep) {
-		err = fmt.Errorf("Invalid document: frontmatter required.\n%s", doc)
-		return
-	}
-	parts := strings.Split(doc, sep)
-	if len(parts) < 3 {
-		err = fmt.Errorf("Invalid document: frontmatter required.\n%s", doc)
-		return
-	}
-	frontmatter = parts[1]
-	body = parts[2]
-	return
-}
-
 func main() {
-	funcMap := template.FuncMap{
-		"sh": sh,
-	}
 	frontmatter, body, err := parseDocument(tmpl)
 	if err != nil {
 		panic(err)
@@ -60,9 +28,7 @@ func main() {
 		panic(err)
 	}
 	fmt.Printf("'%s'", templateMeta)
-	t, err := template.New("foo").Funcs(funcMap).Parse(body)
-	if err != nil {
-		panic(err)
-	}
-	t.Execute(os.Stdout, "hledger is awesome")
+	render(body, map[string]string{
+		"from": "2025-07-15",
+	})
 }
diff --git a/parse.go b/parse.go
index 8796aa3..eeedd36 100644
--- a/parse.go
+++ b/parse.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"gopkg.in/yaml.v3"
 )
@@ -14,3 +15,20 @@ func parseFrontmatter(input string) (meta TemplateMeta, err error) {
 	}
 	return
 }
+
+func parseDocument(doc string) (frontmatter string, body string, err error) {
+	doc = strings.TrimLeft(doc, " \n")
+	sep := "---\n"
+	if !strings.HasPrefix(doc, sep) {
+		err = fmt.Errorf("Invalid document: frontmatter required.\n%s", doc)
+		return
+	}
+	parts := strings.Split(doc, sep)
+	if len(parts) < 3 {
+		err = fmt.Errorf("Invalid document: frontmatter required.\n%s", doc)
+		return
+	}
+	frontmatter = parts[1]
+	body = parts[2]
+	return
+}
diff --git a/render.go b/render.go
new file mode 100644
index 0000000..644d124
--- /dev/null
+++ b/render.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"text/template"
+)
+
+func sh(ctx TemplateContext) func(string) string {
+	return func(command string) string {
+		cmd := exec.Command("sh", "-c", command)
+		for k, v := range ctx {
+			cmd.Env = append(cmd.Env, k+"="+v)
+		}
+		fmt.Println(cmd.Environ())
+		out, err := cmd.Output()
+		if err != nil {
+			return fmt.Sprintf("> Failed to execute the command: %s\n> %s\n", cmd.Args, err.Error())
+		}
+		return fmt.Sprintf("\n```\n%s\n```\n", string(out))
+	}
+}
+
+func render(tmpl string, ctx TemplateContext) {
+	funcMap := template.FuncMap{
+		"sh": sh(ctx),
+	}
+	t, err := template.New("foo").Funcs(funcMap).Parse(tmpl)
+	if err != nil {
+		panic(err)
+	}
+	t.Execute(os.Stdout, ctx)
+}
diff --git a/types.go b/types.go
index e65c8ed..9a2ebeb 100644
--- a/types.go
+++ b/types.go
@@ -19,3 +19,5 @@ type ParamSpec struct {
 	Required bool   `yaml:"required"`
 	Default  string `yaml:"default"`
 }
+
+type TemplateContext map[string]string