feat(commands): refactor and add more commands

commands/view/cat.go

@@ -0,0 +1,17 @@
+package view
+
+import (
+	"github.com/versenilvis/iris/commands/core"
+)
+
+func init() {
+	core.Register(&core.Spec{
+		Name:        "cat",
+		Description: "concatenate and print",
+		Generator:   core.FileGenerator(),
+		Options: []core.Option{
+			{Name: "-n", Description: "number lines"},
+			{Name: "-b", Description: "number non-blank"},
+		},
+	})
+}

commands/view/head.go

@@ -0,0 +1,16 @@
+package view
+
+import (
+	"github.com/versenilvis/iris/commands/core"
+)
+
+func init() {
+	core.Register(&core.Spec{
+		Name:        "head",
+		Description: "output first lines of file",
+		Generator:   core.FileGenerator(),
+		Options: []core.Option{
+			{Name: "-n", Description: "number of lines"},
+		},
+	})
+}

commands/view/less.go

@@ -0,0 +1,13 @@
+package view
+
+import (
+	"github.com/versenilvis/iris/commands/core"
+)
+
+func init() {
+	core.Register(&core.Spec{
+		Name:        "less",
+		Description: "view file contents (scrollable)",
+		Generator:   core.FileGenerator(),
+	})
+}

commands/view/tail.go

@@ -0,0 +1,17 @@
+package view
+
+import (
+	"github.com/versenilvis/iris/commands/core"
+)
+
+func init() {
+	core.Register(&core.Spec{
+		Name:        "tail",
+		Description: "output last lines of file",
+		Generator:   core.FileGenerator(),
+		Options: []core.Option{
+			{Name: "-n", Description: "number of lines"},
+			{Name: "-f", Description: "follow (live updates)"},
+		},
+	})
+}