diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
new file mode 100644
index 0000000..6444642
--- /dev/null
+++ b/.github/workflows/release.yml
@@ -0,0 +1,134 @@
+name: Release
+
+on:
+  workflow_dispatch:
+
+  push:
+    tags:
+      - 'v*'
+
+    branches:
+      - master
+
+    paths:
+      - "cmd/run/**"
+      - ".github/**"
+      - "pkg/**"
+      - go.* # go.mod, and go.sum
+      - flake.*
+
+permissions:
+  contents: write
+  packages: write
+
+jobs:
+  build-binary:
+    strategy:
+      fail-fast: true
+      matrix:
+        os: [ubuntu-latest, macos-14, macos-13]
+        arch: [amd64, arm64]
+        include:
+          - os: ubuntu-latest
+            platform: linux
+
+          - os: macos-13
+            platform: darwin
+
+          - os: macos-14
+            platform: darwin
+        exclude:
+          - os: macos-14
+            arch: amd64
+          - os: macos-13
+            arch: arm64
+
+    name: Building run-${{ matrix.platform }}-${{ matrix.arch }}
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: nxtcoder17/actions/setup-cache-go@v1
+        with:
+          cache_key: "run-${{ matrix.platform }}-${{ matrix.arch }}"
+          working_directory: .
+
+      - uses: nxtcoder17/actions/generate-image-tag@v1
+
+      - uses: nxtcoder17/actions/setup-nix-cachix@v1
+        with:
+          flake_lock: "./flake.lock"
+          nix_develop_arguments: ".#default"
+          cachix_cache_name: ${{ secrets.CACHIX_CACHE_NAME }}
+          cachix_auth_token:  ${{ secrets.CACHIX_AUTH_TOKEN }}
+
+      - name: Build Binary
+        shell: bash
+        env:
+          CGO_ENABLED: 0
+        run: |+
+          binary=bin/run-${{ matrix.platform }}-${{ matrix.arch }}
+          go build -o $binary -ldflags="-s -w" -tags urfave_cli_no_docs cmd/run/main.go
+
+          if [ "${{ matrix.platform }}" = "linux" ]; then
+            upx $binary
+          fi
+
+      - name: Upload Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: run-${{ matrix.platform }}-${{ matrix.arch }}
+          path: bin/*
+
+  release:
+    needs: build-binary
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download all artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: ${{ github.workspace }}/binaries
+          pattern: "run-*"
+
+      - name: flattening all the executable artifacts
+        shell: bash
+        run: |+
+          ls -R ${{ github.workspace }}/binaries
+          mkdir -p  ${{ github.workspace }}/upload/binaries
+          shopt -s globstar
+          file ./** | grep 'executable,' | awk -F: '{print $1}' | xargs -I {} cp {} ${{ github.workspace }}/upload/binaries
+          shopt -u globstar
+
+      - uses: nxtcoder17/actions/generate-image-tag@v1
+
+      - name: running for master branch
+        if: startsWith(github.ref, 'refs/heads/master')
+        run: |+
+          echo "IMAGE_TAG=nightly" | tee -a $GITHUB_ENV | tee -a $GITHUB_OUTPUT
+
+      - name: ensure github release exists
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |+
+          set +e
+          gh release list -R ${{ github.repository }}  | grep -i $IMAGE_TAG
+          exit_code=$?
+          if [ $exit_code -ne 0 ]; then
+            gh release create $IMAGE_TAG -R ${{ github.repository }} --generate-notes --prerelease
+          fi
+
+      - name: upload to github release
+        shell: bash
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |+
+          gh release upload $IMAGE_TAG -R ${{github.repository}} ${{github.workspace}}/upload/binaries/*
+
+      - name: mark release as latest
+        if: startsWith(github.ref, 'refs/tags/')
+        env:
+          GH_TOKEN: ${{ github.token }}
+        shell: bash
+        run: |+
+          gh release edit $IMAGE_TAG -R ${{ github.repository }} --latest
diff --git a/Runfile b/Runfile
index 65116bd..38097d4 100644
--- a/Runfile
+++ b/Runfile
@@ -11,6 +11,11 @@ tasks:
         echo "DONE"
 
   example:
+    dir: ./examples
     cmd: 
       - |+
-        run -f ./examples/Runfile cook
+        run cook clean
+
+  test:
+    cmd:
+      - go test -json ./pkg/runfile | gotestfmt
diff --git a/cmd/run/main.go b/cmd/run/main.go
index bfe2a49..c8a6c14 100644
--- a/cmd/run/main.go
+++ b/cmd/run/main.go
@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"syscall"
 
+	"github.com/nxtcoder17/fwatcher/pkg/logging"
 	"github.com/nxtcoder17/runfile/pkg/runfile"
 	"github.com/urfave/cli/v3"
 )
@@ -26,6 +27,23 @@ func main() {
 				Aliases: []string{"f"},
 				Value:   "",
 			},
+
+			&cli.BoolFlag{
+				Name:    "parallel",
+				Aliases: []string{"p"},
+				Value:   false,
+			},
+
+			&cli.BoolFlag{
+				Name:    "watch",
+				Aliases: []string{"w"},
+				Value:   false,
+			},
+
+			&cli.BoolFlag{
+				Name:  "debug",
+				Value: false,
+			},
 		},
 		EnableShellCompletion: true,
 		ShellComplete: func(ctx context.Context, c *cli.Command) {
@@ -38,7 +56,7 @@ func main() {
 				panic(err)
 			}
 
-			runfile, err := runfile.ParseRunFile(runfilePath)
+			runfile, err := runfile.Parse(runfilePath)
 			if err != nil {
 				panic(err)
 			}
@@ -48,11 +66,18 @@ func main() {
 			}
 		},
 		Action: func(ctx context.Context, c *cli.Command) error {
-			if c.Args().Len() > 1 {
-				return fmt.Errorf("too many arguments")
-			}
-			if c.Args().Len() != 1 {
-				return fmt.Errorf("missing argument")
+			parallel := c.Bool("parallel")
+			watch := c.Bool("watch")
+			debug := c.Bool("debug")
+
+			logging.NewSlogLogger(logging.SlogOptions{
+				ShowCaller:         debug,
+				ShowDebugLogs:      debug,
+				SetAsDefaultLogger: true,
+			})
+
+			if c.Args().Len() < 1 {
+				return fmt.Errorf("missing argument, at least one argument is required")
 			}
 
 			runfilePath, err := locateRunfile(c)
@@ -60,13 +85,41 @@ func main() {
 				return err
 			}
 
-			runfile, err := runfile.ParseRunFile(runfilePath)
+			rf, err := runfile.Parse(runfilePath)
 			if err != nil {
 				panic(err)
 			}
 
-			s := c.Args().First()
-			return runfile.Run(ctx, s)
+			args := make([]string, 0, len(c.Args().Slice()))
+			for _, arg := range c.Args().Slice() {
+				if arg == "-p" || arg == "--parallel" {
+					parallel = true
+					continue
+				}
+
+				if arg == "-w" || arg == "--watch" {
+					watch = true
+					continue
+				}
+
+				if arg == "--debug" {
+					debug = true
+					continue
+				}
+
+				args = append(args, arg)
+			}
+
+			if parallel && watch {
+				return fmt.Errorf("parallel and watch can't be set together")
+			}
+
+			return rf.Run(ctx, runfile.RunArgs{
+				Tasks:             args,
+				ExecuteInParallel: parallel,
+				Watch:             watch,
+				Debug:             debug,
+			})
 		},
 	}
 
diff --git a/docs/requirements-for-a-run-target.md b/docs/requirements-for-a-run-target.md
new file mode 100644
index 0000000..d738800
--- /dev/null
+++ b/docs/requirements-for-a-run-target.md
@@ -0,0 +1,27 @@
+---
+Github Issue: https://github.com/nxtcoder17/Runfile/issues/8
+---
+
+### Expectations from this implementation ?
+
+I would like to be able to do stuffs like:
+- whether these environment variables have been defined 
+- whether this filepath exists or not
+- whether `this command` or script runs sucessfully
+
+And, when answers to these questsions are `true`, then only run the target, otherwise throw the errors
+
+### Problems with Taskfile.dev implementation
+
+They have 2 ways to tackle this, with 
+
+- `requires`: but, it works with vars only, ~no environment variables~
+
+- `preconditions`: test conditions must be a valid linux `test` command, which assumes everyone knows how to read bash's `test` or `if` statements
+
+
+### My Approach
+
+1. Support for `test` commands, must be there, for advanced users
+
+2. But, for simpler use cases, there should be alternate ways to do it, something that whole team just understands.
diff --git a/examples/Runfile b/examples/Runfile
index 3130c74..f2cdcc4 100644
--- a/examples/Runfile
+++ b/examples/Runfile
@@ -8,31 +8,43 @@ tasks:
       k2: 'f"\( asfsadfssdfas asfd $Asdfasdfa'
       k3:
         sh: echo -n "hello"
+      k4:
+        required: true
     dotenv:
-      - .secrets/env
+      - ../.secrets/env
     cmd: 
-      - echo "hi hello"
-      - echo "value of k1 is '$k1'"
-      - echo "value of k2 is '$k2'"
-      - echo "value of k3 is '$k3'"
-      - echo "value of key_id (from .dotenv) is '$key_id', ${#key_id}"
+      # - sleep 5
+      # - echo "hi hello"
+      # - echo "value of k1 is '$k1'"
+      # - echo "value of k2 is '$k2'"
+      # - echo "value of k3 is '$k3'"
+      # - echo "value of key_id (from .dotenv) is '$key_id', ${#key_id}"
+      - echo "hello from cook"
 
   clean:
     name: clean
     shell: ["python", "-c"]
     dotenv:
-      - .secrets/env
+      - ../.secrets/env
     cmd:
+      - run: laundry
+        # vars:
+        #   k1: v1
       - |+
         import secrets
         import os
-        print(os.environ['key_id'])
-        # print(secrets.token_hex(32))
+        import time
+        # print("key_id from env: ", os.environ['key_id'])
+        time.sleep(2)
+        print("hello from clean")
+        print(secrets.token_hex(32))
+
   laundry:
     name: laundry
     shell: ["node", "-e"]
     cmd: 
-      - console.log("laundry")
+      - run: cook
+      - console.log("hello from laundry")
   eat:
     name: eat
     cmd: 
diff --git a/flake.nix b/flake.nix
index dad0011..633c673 100644
--- a/flake.nix
+++ b/flake.nix
@@ -26,6 +26,8 @@
             go_1_22
 
             upx
+
+            gotestfmt
           ];
 
           shellHook = ''
diff --git a/go.mod b/go.mod
index e4160a9..2deb5de 100644
--- a/go.mod
+++ b/go.mod
@@ -3,8 +3,26 @@ module github.com/nxtcoder17/runfile
 go 1.22.7
 
 require (
+	github.com/go-task/slim-sprig/v3 v3.0.0
+	github.com/joho/godotenv v1.5.1
+	github.com/nxtcoder17/fwatcher v1.0.1
 	github.com/urfave/cli/v3 v3.0.0-alpha9
+	golang.org/x/sync v0.8.0
 	sigs.k8s.io/yaml v1.4.0
 )
 
-require github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
+require (
+	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/charmbracelet/lipgloss v0.13.0 // indirect
+	github.com/charmbracelet/log v0.4.0 // indirect
+	github.com/charmbracelet/x/ansi v0.1.4 // indirect
+	github.com/go-logfmt/logfmt v0.6.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-runewidth v0.0.15 // indirect
+	github.com/muesli/termenv v0.15.2 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 // indirect
+	golang.org/x/exp v0.0.0-20231006140011-7918f672742d // indirect
+	golang.org/x/sys v0.19.0 // indirect
+)
diff --git a/go.sum b/go.sum
index 8c4c5ae..7fb069a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,15 +1,49 @@
+github.com/aymanbagabas/go-osc52/v2 v2.0.1 h1:HwpRHbFMcZLEVr42D4p7XBqjyuxQH5SMiErDT4WkJ2k=
+github.com/aymanbagabas/go-osc52/v2 v2.0.1/go.mod h1:uYgXzlJ7ZpABp8OJ+exZzJJhRNQ2ASbcXHWsFqH8hp8=
+github.com/charmbracelet/lipgloss v0.13.0 h1:4X3PPeoWEDCMvzDvGmTajSyYPcZM4+y8sCA/SsA3cjw=
+github.com/charmbracelet/lipgloss v0.13.0/go.mod h1:nw4zy0SBX/F/eAO1cWdcvy6qnkDUxr8Lw7dvFrAIbbY=
+github.com/charmbracelet/log v0.4.0 h1:G9bQAcx8rWA2T3pWvx7YtPTPwgqpk7D68BX21IRW8ZM=
+github.com/charmbracelet/log v0.4.0/go.mod h1:63bXt/djrizTec0l11H20t8FDSvA4CRZJ1KH22MdptM=
+github.com/charmbracelet/x/ansi v0.1.4 h1:IEU3D6+dWwPSgZ6HBH+v6oUuZ/nVawMiWj5831KfiLM=
+github.com/charmbracelet/x/ansi v0.1.4/go.mod h1:dk73KoMTT5AX5BsX0KrqhsTqAnhZZoCBjs7dGWp4Ktw=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-logfmt/logfmt v0.6.0 h1:wGYYu3uicYdqXVgoYbvnkrPVXkuLM1p1ifugDMEdRi4=
+github.com/go-logfmt/logfmt v0.6.0/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
+github.com/go-task/slim-sprig/v3 v3.0.0 h1:sUs3vkvUymDpBKi3qH1YSqBQk9+9D/8M2mN1vB6EwHI=
+github.com/go-task/slim-sprig/v3 v3.0.0/go.mod h1:W848ghGpv3Qj3dhTPRyJypKRiqCdHZiAzKg9hl15HA8=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/lucasb-eyer/go-colorful v1.2.0 h1:1nnpGOrhyZZuNyfu1QjKiUICQ74+3FNCN69Aj6K7nkY=
+github.com/lucasb-eyer/go-colorful v1.2.0/go.mod h1:R4dSotOR9KMtayYi1e77YzuveK+i7ruzyGqttikkLy0=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/mattn/go-runewidth v0.0.15 h1:UNAjwbU9l54TA3KzvqLGxwWjHmMgBUVhBiTjelZgg3U=
+github.com/mattn/go-runewidth v0.0.15/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/muesli/termenv v0.15.2 h1:GohcuySI0QmI3wN8Ok9PtKGkgkFIk7y6Vpb5PvrY+Wo=
+github.com/muesli/termenv v0.15.2/go.mod h1:Epx+iuz8sNs7mNKhxzH4fWXGNpZwUaJKRS1noLXviQ8=
+github.com/nxtcoder17/fwatcher v1.0.1 h1:Rqy+7etcGv9L1KIoK8YGGpAhdXW/pkfkXQwdlJzL1a8=
+github.com/nxtcoder17/fwatcher v1.0.1/go.mod h1:MNmSwXYOrqp7U1pUxh0GWB5skpjFTWTQXhAA0+sPJcU=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
-github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
+github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/urfave/cli/v3 v3.0.0-alpha9 h1:P0RMy5fQm1AslQS+XCmy9UknDXctOmG/q/FZkUFnJSo=
 github.com/urfave/cli/v3 v3.0.0-alpha9/go.mod h1:0kK/RUFHyh+yIKSfWxwheGndfnrvYSmYFVeKCh03ZUc=
 github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1 h1:gEOO8jv9F4OT7lGCjxCBTO/36wtF6j2nSip77qHd4x4=
 github.com/xrash/smetrics v0.0.0-20240521201337-686a1a2994c1/go.mod h1:Ohn+xnUBiLI6FVj/9LpzZWtj1/D6lUovWYBkxHVV3aM=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d h1:jtJma62tbqLibJ5sFQz8bKtEM8rJBtfilJ2qTU199MI=
+golang.org/x/exp v0.0.0-20231006140011-7918f672742d/go.mod h1:ldy0pHrwJyGW56pPQzzkH36rKxoZW1tw7ZJpeKx+hdo=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
+golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
diff --git a/main.go b/main.go
deleted file mode 100644
index 57040c6..0000000
--- a/main.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package main
-
-import "fmt"
-
-func main() {
-	fmt.Println("RUN FILE")
-}
diff --git a/pkg/functions/helpers.go b/pkg/functions/helpers.go
new file mode 100644
index 0000000..51b6ccb
--- /dev/null
+++ b/pkg/functions/helpers.go
@@ -0,0 +1,22 @@
+package functions
+
+func DefaultIfNil[T any](v *T, dv T) T {
+	if v == nil {
+		return dv
+	}
+	return *v
+}
+
+// Must panics if err is not nil
+// It is intended to be used very sparingly, and only in cases where the caller is
+// certain that the error will never be nil in ideal scenarios
+func Must[T any](v T, err error) T {
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func New[T any](v T) *T {
+	return &v
+}
diff --git a/pkg/runfile/errors/errors.go b/pkg/runfile/errors/errors.go
new file mode 100644
index 0000000..d7da7c4
--- /dev/null
+++ b/pkg/runfile/errors/errors.go
@@ -0,0 +1,126 @@
+package errors
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type Context struct {
+	Task    string
+	Runfile string
+
+	message *string
+	err     error
+}
+
+func (c Context) WithMessage(msg string) Context {
+	c.message = &msg
+	return c
+}
+
+func (c Context) WithErr(err error) Context {
+	c.err = err
+	return c
+}
+
+func (c Context) ToString() string {
+	m := map[string]string{
+		"task":    c.Task,
+		"runfile": c.Runfile,
+	}
+	if c.message != nil {
+		m["message"] = *c.message
+	}
+
+	if c.err != nil {
+		m["err"] = c.err.Error()
+	}
+
+	b, err := json.Marshal(m)
+	if err != nil {
+		panic(err)
+	}
+
+	return string(b)
+}
+
+func (e Context) Error() string {
+	return e.ToString()
+}
+
+type (
+	ErrTaskInvalid struct{ Context }
+)
+
+type ErrTaskFailedRequirements struct {
+	Context
+	Requirement string
+}
+
+func (e ErrTaskFailedRequirements) Error() string {
+	if e.message == nil {
+		e.Context = e.Context.WithMessage(fmt.Sprintf("failed (requirement: %q)", e.Requirement))
+	}
+	return e.Context.Error()
+}
+
+type TaskNotFound struct {
+	Context
+}
+
+func (e TaskNotFound) Error() string {
+	// return fmt.Sprintf("[task] %s, not found in [Runfile] at %s", e.TaskName, e.RunfilePath)
+	if e.message == nil {
+		e.Context = e.Context.WithMessage("Not Found")
+	}
+	return e.Context.Error()
+}
+
+type ErrTaskGeneric struct {
+	Context
+}
+
+type InvalidWorkingDirectory struct {
+	Context
+}
+
+func (e InvalidWorkingDirectory) Error() string {
+	// return fmt.Sprintf("[task] %s, not found in [Runfile] at %s", e.TaskName, e.RunfilePath)
+	if e.message == nil {
+		e.Context = e.Context.WithMessage("Invalid Working Directory")
+	}
+	return e.Context.Error()
+}
+
+type InvalidDotEnv struct {
+	Context
+}
+
+func (e InvalidDotEnv) Error() string {
+	if e.message == nil {
+		e.Context = e.Context.WithMessage("invalid dotenv")
+	}
+	return e.Context.Error()
+}
+
+type InvalidEnvVar struct {
+	Context
+}
+
+func (e InvalidEnvVar) Error() string {
+	if e.message == nil {
+		e.Context = e.Context.WithMessage("invalid dotenv")
+	}
+	return e.Context.Error()
+}
+
+type IncorrectCommand struct {
+	Context
+}
+
+func (e IncorrectCommand) Error() string {
+	if e.message == nil {
+		e.Context = e.Context.WithMessage("incorrect command")
+	}
+	return e.Context.Error()
+}
diff --git a/pkg/runfile/parser.go b/pkg/runfile/parser.go
index 33ae39b..91c2235 100644
--- a/pkg/runfile/parser.go
+++ b/pkg/runfile/parser.go
@@ -1,55 +1,41 @@
 package runfile
 
 import (
-	"bufio"
 	"fmt"
+	"io"
 	"os"
-	"strconv"
-	"strings"
+	"path/filepath"
 
-	"sigs.k8s.io/yaml"
+	"github.com/joho/godotenv"
 )
 
-func ParseRunFile(file string) (*RunFile, error) {
-	var runfile RunFile
-	f, err := os.ReadFile(file)
-	if err != nil {
-		return &runfile, err
-	}
-	err = yaml.Unmarshal(f, &runfile)
-	if err != nil {
-		return &runfile, err
-	}
-	return &runfile, nil
+func parseDotEnv(reader io.Reader) (map[string]string, error) {
+	return godotenv.Parse(reader)
 }
 
 // parseDotEnv parses the .env file and returns a slice of strings as in os.Environ()
-func parseDotEnv(files ...string) ([]string, error) {
-	results := make([]string, 0, 5)
+func parseDotEnvFiles(files ...string) (map[string]string, error) {
+	results := make(map[string]string)
 
 	for i := range files {
+		if !filepath.IsAbs(files[i]) {
+			return nil, fmt.Errorf("dotenv file path %s, must be absolute", files[i])
+		}
+
 		f, err := os.Open(files[i])
 		if err != nil {
 			return nil, err
 		}
+		m, err := parseDotEnv(f)
+		if err != nil {
+			return nil, err
+		}
+		f.Close()
 
-		s := bufio.NewScanner(f)
-		for s.Scan() {
-			s2 := strings.SplitN(s.Text(), "=", 2)
-			if len(s2) != 2 {
-				continue
-			}
-			s, _ := strconv.Unquote(string(s2[1]))
-
-			// os.Setenv(s2[0], s2[1])
-			os.Setenv(s2[0], s)
-			results = append(results, s2[0])
+		for k, v := range m {
+			results[k] = v
 		}
-	}
 
-	for i := range results {
-		v := os.Getenv(results[i])
-		results[i] = fmt.Sprintf("%s=%v", results[i], v)
 	}
 
 	return results, nil
diff --git a/pkg/runfile/parser_test.go b/pkg/runfile/parser_test.go
new file mode 100644
index 0000000..a33331f
--- /dev/null
+++ b/pkg/runfile/parser_test.go
@@ -0,0 +1,103 @@
+package runfile
+
+import (
+	"bytes"
+	"io"
+	"reflect"
+	"testing"
+)
+
+func Test_parseDotEnvFile(t *testing.T) {
+	type args struct {
+		reader io.Reader
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    map[string]string
+		wantErr bool
+	}{
+		{
+			name: "key=",
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key=`)),
+			},
+			want: map[string]string{
+				"key": "",
+			},
+			wantErr: false,
+		},
+		{
+			name: "key=1",
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key=1`)),
+			},
+			want: map[string]string{
+				"key": "1",
+			},
+			wantErr: false,
+		},
+		{
+			name: "key=one",
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key=one`)),
+			},
+			want: map[string]string{
+				"key": "one",
+			},
+			wantErr: false,
+		},
+		{
+			name: "key='one'",
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key='one'`)),
+			},
+			want: map[string]string{
+				"key": "one",
+			},
+			wantErr: false,
+		},
+		{
+			name: `key='o"ne'`,
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key='o"ne'`)),
+			},
+			want: map[string]string{
+				"key": `o"ne`,
+			},
+			wantErr: false,
+		},
+		{
+			name: `key="one"`,
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key="one"`)),
+			},
+			want: map[string]string{
+				"key": `one`,
+			},
+			wantErr: false,
+		},
+		{
+			name: `key=sample==`,
+			args: args{
+				reader: bytes.NewBuffer([]byte(`key=sample==`)),
+			},
+			want: map[string]string{
+				"key": `sample==`,
+			},
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := parseDotEnv(tt.args.reader)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("parseDotEnvFile() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("parseDotEnvFile()\n\t got: %#v,\n\twant: %#v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/pkg/runfile/run.go b/pkg/runfile/run.go
index 21b70ef..ae96ded 100644
--- a/pkg/runfile/run.go
+++ b/pkg/runfile/run.go
@@ -1,24 +1,28 @@
 package runfile
 
 import (
-	"bytes"
 	"context"
-	"fmt"
 	"io"
+	"log/slog"
 	"os"
 	"os/exec"
+
+	"github.com/nxtcoder17/runfile/pkg/runfile/errors"
+	"golang.org/x/sync/errgroup"
 )
 
-type runArgs struct {
-	shell []string
-	env   []string // [key=value, key=value, ...]
-	cmd   string
+type cmdArgs struct {
+	shell      []string
+	env        []string // [key=value, key=value, ...]
+	workingDir string
+
+	cmd string
 
 	stdout io.Writer
 	stderr io.Writer
 }
 
-func runInShell(ctx context.Context, args runArgs) error {
+func createCommand(ctx context.Context, args cmdArgs) *exec.Cmd {
 	if args.shell == nil {
 		args.shell = []string{"sh", "-c"}
 	}
@@ -32,75 +36,86 @@ func runInShell(ctx context.Context, args runArgs) error {
 	}
 
 	shell := args.shell[0]
-	// f, err := os.CreateTemp(os.TempDir(), "runfile-")
-	// if err != nil {
-	// 	return err
-	// }
-	// f.WriteString(args.cmd)
-	// f.Close()
-
-	// cargs := append(args.shell[1:], f.Name())
+
 	cargs := append(args.shell[1:], args.cmd)
 	c := exec.CommandContext(ctx, shell, cargs...)
+	c.Dir = args.workingDir
 	c.Env = args.env
 	c.Stdout = args.stdout
 	c.Stderr = args.stderr
-	return c.Run()
+	return c
 }
 
-func (r *RunFile) Run(ctx context.Context, taskName string) error {
-	task, ok := r.Tasks[taskName]
-	if !ok {
-		return fmt.Errorf("task %s not found", taskName)
+func (rf *Runfile) runTask(ctx context.Context, taskName string) error {
+	pt, err := ParseTask(ctx, rf, taskName)
+	if err != nil {
+		return err
 	}
 
-	env := make([]string, len(task.Env))
-	for k, v := range task.Env {
-		switch v := v.(type) {
-		case string:
-			env = append(env, fmt.Sprintf("%s=%s", k, v))
-		case map[string]any:
-			shcmd, ok := v["sh"]
-			if !ok {
-				return fmt.Errorf("env %s is not a string", k)
-			}
-
-			s, ok := shcmd.(string)
-			if !ok {
-				return fmt.Errorf("shell cmd is not a string")
-			}
+	// slog.Default().Info("parsing", "task", pt)
 
-			value := new(bytes.Buffer)
-
-			if err := runInShell(ctx, runArgs{
-				shell:  task.Shell,
-				env:    os.Environ(),
-				cmd:    s,
-				stdout: value,
-			}); err != nil {
+	for _, command := range pt.Commands {
+		if command.Run != "" {
+			if err := rf.runTask(ctx, command.Run); err != nil {
 				return err
 			}
-			env = append(env, fmt.Sprintf("%s=%v", k, value.String()))
-		default:
-			panic(fmt.Sprintf("env %s is not a string (%T)", k, v))
+			continue
+		}
+
+		cmd := createCommand(ctx, cmdArgs{
+			shell:      pt.Shell,
+			env:        pt.Environ,
+			cmd:        command.Command,
+			workingDir: pt.WorkingDir,
+		})
+		if err := cmd.Run(); err != nil {
+			return err
 		}
 	}
 
-	// parsing dotenv
-	s, err := parseDotEnv(task.DotEnv...)
-	if err != nil {
-		return err
+	return nil
+}
+
+type RunArgs struct {
+	Tasks             []string
+	ExecuteInParallel bool
+	Watch             bool
+	Debug             bool
+}
+
+func (rf *Runfile) Run(ctx context.Context, args RunArgs) error {
+	for _, v := range args.Tasks {
+		if _, ok := rf.Tasks[v]; !ok {
+			return errors.TaskNotFound{Context: errors.Context{
+				Task:    v,
+				Runfile: rf.attrs.RunfilePath,
+			}}
+		}
 	}
 
-	// INFO: keys from task.Env will override those coming from dotenv files, when duplicated
-	env = append(s, env...)
+	if args.ExecuteInParallel {
+		slog.Default().Debug("running in parallel mode", "tasks", args.Tasks)
+		g := new(errgroup.Group)
 
-	for _, cmd := range task.Commands {
-		runInShell(ctx, runArgs{
-			shell: task.Shell,
-			env:   append(os.Environ(), env...),
-			cmd:   cmd,
-		})
+		for _, tn := range args.Tasks {
+			g.Go(func() error {
+				return rf.runTask(ctx, tn)
+			})
+		}
+
+		// Wait for all tasks to finish
+		if err := g.Wait(); err != nil {
+			return err
+		}
+
+		return nil
 	}
+
+	for _, tn := range args.Tasks {
+		if err := rf.runTask(ctx, tn); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
diff --git a/pkg/runfile/run_test.go b/pkg/runfile/run_test.go
new file mode 100644
index 0000000..a5515d8
--- /dev/null
+++ b/pkg/runfile/run_test.go
@@ -0,0 +1 @@
+package runfile
diff --git a/pkg/runfile/runfile.go b/pkg/runfile/runfile.go
new file mode 100644
index 0000000..bc483da
--- /dev/null
+++ b/pkg/runfile/runfile.go
@@ -0,0 +1,35 @@
+package runfile
+
+import (
+	"os"
+	"path/filepath"
+
+	fn "github.com/nxtcoder17/runfile/pkg/functions"
+	"sigs.k8s.io/yaml"
+)
+
+type attrs struct {
+	RunfilePath string
+}
+
+type Runfile struct {
+	attrs attrs
+
+	Version string
+	Tasks   map[string]Task `json:"tasks"`
+}
+
+func Parse(file string) (*Runfile, error) {
+	var runfile Runfile
+	f, err := os.ReadFile(file)
+	if err != nil {
+		return &runfile, err
+	}
+	err = yaml.Unmarshal(f, &runfile)
+	if err != nil {
+		return nil, err
+	}
+
+	runfile.attrs.RunfilePath = fn.Must(filepath.Abs(file))
+	return &runfile, nil
+}
diff --git a/pkg/runfile/task-parser.go b/pkg/runfile/task-parser.go
new file mode 100644
index 0000000..e77901f
--- /dev/null
+++ b/pkg/runfile/task-parser.go
@@ -0,0 +1,197 @@
+package runfile
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"text/template"
+
+	sprig "github.com/go-task/slim-sprig/v3"
+	fn "github.com/nxtcoder17/runfile/pkg/functions"
+	"github.com/nxtcoder17/runfile/pkg/runfile/errors"
+)
+
+type ParsedTask struct {
+	Shell      []string      `json:"shell"`
+	WorkingDir string        `json:"workingDir"`
+	Environ    []string      `json:"environ"`
+	Commands   []CommandJson `json:"commands"`
+}
+
+func ParseTask(ctx context.Context, rf *Runfile, taskName string) (*ParsedTask, error) {
+	errctx := errors.Context{Task: taskName, Runfile: rf.attrs.RunfilePath}
+
+	task, ok := rf.Tasks[taskName]
+	if !ok {
+		return nil, errors.TaskNotFound{Context: errctx}
+	}
+
+	for _, requirement := range task.Requires {
+		if requirement == nil {
+			continue
+		}
+
+		if requirement.Sh != nil {
+			cmd := createCommand(ctx, cmdArgs{
+				shell:      []string{"sh", "-c"},
+				env:        os.Environ(),
+				workingDir: filepath.Dir(rf.attrs.RunfilePath),
+				cmd:        *requirement.Sh,
+				stdout:     fn.Must(os.OpenFile(os.DevNull, os.O_WRONLY, 0o755)),
+				stderr:     fn.Must(os.OpenFile(os.DevNull, os.O_WRONLY, 0o755)),
+			})
+			if err := cmd.Run(); err != nil {
+				return nil, errors.ErrTaskFailedRequirements{Context: errctx.WithErr(err), Requirement: *requirement.Sh}
+			}
+			continue
+		}
+
+		if requirement.GoTmpl != nil {
+			t := template.New("requirement")
+			t = t.Funcs(sprig.FuncMap())
+			templateExpr := fmt.Sprintf(`{{ %s }}`, *requirement.GoTmpl)
+			t, err := t.Parse(templateExpr)
+			if err != nil {
+				return nil, err
+			}
+			b := new(bytes.Buffer)
+			if err := t.ExecuteTemplate(b, "requirement", map[string]string{}); err != nil {
+				return nil, err
+			}
+
+			if b.String() != "true" {
+				return nil, errors.ErrTaskFailedRequirements{Context: errctx.WithErr(fmt.Errorf("`%s` evaluated to `%s` (wanted: `true`)", templateExpr, b.String())), Requirement: *requirement.GoTmpl}
+			}
+
+			continue
+		}
+	}
+
+	if task.Shell == nil {
+		task.Shell = []string{"sh", "-c"}
+	}
+
+	if task.Dir == nil {
+		task.Dir = fn.New(fn.Must(os.Getwd()))
+	}
+
+	fi, err := os.Stat(*task.Dir)
+	if err != nil {
+		return nil, errors.InvalidWorkingDirectory{Context: errctx.WithErr(err)}
+	}
+
+	if !fi.IsDir() {
+		return nil, errors.InvalidWorkingDirectory{Context: errctx.WithErr(fmt.Errorf("path (%s), is not a directory", *task.Dir))}
+	}
+
+	dotenvPaths, err := resolveDotEnvFiles(filepath.Dir(rf.attrs.RunfilePath), task.DotEnv...)
+	if err != nil {
+		return nil, errors.InvalidDotEnv{Context: errctx.WithErr(err).WithMessage("failed to resolve dotenv paths")}
+	}
+
+	dotenvVars, err := parseDotEnvFiles(dotenvPaths...)
+	if err != nil {
+		return nil, errors.InvalidDotEnv{Context: errctx.WithErr(err).WithMessage("failed to parse dotenv files")}
+	}
+
+	env := make([]string, 0, len(os.Environ())+len(dotenvVars))
+	if !task.ignoreSystemEnv {
+		env = append(env, os.Environ()...)
+	}
+	for k, v := range dotenvVars {
+		env = append(env, fmt.Sprintf("%s=%v", k, v))
+	}
+
+	// INFO: keys from task.Env will override those coming from dotenv files, when duplicated
+	envVars, err := parseEnvVars(ctx, task.Env, EvaluationArgs{
+		Shell: task.Shell,
+		Env:   dotenvVars,
+	})
+	if err != nil {
+		return nil, errors.InvalidEnvVar{Context: errctx.WithErr(err).WithMessage("failed to parse/evaluate env vars")}
+	}
+
+	for k, v := range envVars {
+		env = append(env, fmt.Sprintf("%s=%v", k, v))
+	}
+
+	commands := make([]CommandJson, 0, len(task.Commands))
+	for i := range task.Commands {
+		c2, err := parseCommand(rf, task.Commands[i])
+		if err != nil {
+			return nil, errors.IncorrectCommand{Context: errctx.WithErr(err).WithMessage(fmt.Sprintf("failed to parse command: %+v", task.Commands[i]))}
+		}
+		commands = append(commands, *c2)
+	}
+
+	return &ParsedTask{
+		Shell:      task.Shell,
+		WorkingDir: *task.Dir,
+		Environ:    env,
+		Commands:   commands,
+	}, nil
+}
+
+// returns absolute paths to dotenv files
+func resolveDotEnvFiles(pwd string, dotEnvFiles ...string) ([]string, error) {
+	paths := make([]string, 0, len(dotEnvFiles))
+
+	for _, v := range dotEnvFiles {
+		dotenvPath := v
+		if !filepath.IsAbs(v) {
+			dotenvPath = filepath.Join(pwd, v)
+		}
+		fi, err := os.Stat(dotenvPath)
+		if err != nil {
+			return nil, err
+		}
+
+		if fi.IsDir() {
+			return nil, fmt.Errorf("dotenv file must be a file, but %s is a directory", v)
+		}
+
+		paths = append(paths, dotenvPath)
+	}
+
+	return paths, nil
+}
+
+func parseCommand(rf *Runfile, command any) (*CommandJson, error) {
+	switch c := command.(type) {
+	case string:
+		{
+			return &CommandJson{
+				Command: c,
+			}, nil
+		}
+	case map[string]any:
+		{
+			var cj CommandJson
+			b, err := json.Marshal(c)
+			if err != nil {
+				return nil, err
+			}
+
+			if err := json.Unmarshal(b, &cj); err != nil {
+				return nil, err
+			}
+
+			if cj.Run == "" {
+				return nil, fmt.Errorf("key: 'run', must be specified when setting command in json format")
+			}
+
+			if _, ok := rf.Tasks[cj.Run]; !ok {
+				return nil, fmt.Errorf("[run target]: %s, not found in Runfile (%s)", cj.Run, rf.attrs.RunfilePath)
+			}
+
+			return &cj, nil
+		}
+	default:
+		{
+			return nil, fmt.Errorf("invalid command")
+		}
+	}
+}
diff --git a/pkg/runfile/task-parser_test.go b/pkg/runfile/task-parser_test.go
new file mode 100644
index 0000000..60e497f
--- /dev/null
+++ b/pkg/runfile/task-parser_test.go
@@ -0,0 +1,656 @@
+package runfile
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+
+	fn "github.com/nxtcoder17/runfile/pkg/functions"
+)
+
+func TestParseTask(t *testing.T) {
+	type args struct {
+		ctx      context.Context
+		rf       *Runfile
+		taskName string
+	}
+
+	areEqual := func(t *testing.T, got, want *ParsedTask) bool {
+		if want == nil {
+			return false
+		}
+
+		if strings.Join(got.Shell, ",") != strings.Join(want.Shell, ",") {
+			t.Logf("shell not equal")
+			return false
+		}
+
+		slices.Sort(got.Environ)
+		slices.Sort(want.Environ)
+
+		if strings.Join(got.Environ, ",") != strings.Join(want.Environ, ",") {
+			t.Logf("environ not equal")
+			return false
+		}
+
+		if got.WorkingDir != want.WorkingDir {
+			t.Logf("working dir not equal")
+			return false
+		}
+
+		if fmt.Sprintf("%#v", got.Commands) != fmt.Sprintf("%#v", want.Commands) {
+			t.Logf("commands not equal:\n got:\t%#v\nwant:\t%#v", got.Commands, want.Commands)
+			return false
+		}
+
+		return true
+	}
+
+	// for dotenv test
+	dotenvTestFile, err := os.CreateTemp(os.TempDir(), ".env")
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	fmt.Fprintf(dotenvTestFile, "hello=world\n")
+	dotenvTestFile.Close()
+
+	type test struct {
+		name    string
+		args    args
+		want    *ParsedTask
+		wantErr bool
+	}
+
+	testRequires := []test{
+		{
+			name: "[requires] condition specified, but it neither has 'sh' or 'gotmpl' key",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           nil,
+							ignoreSystemEnv: true,
+							Requires: []*Requires{
+								{},
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+
+		{
+			name: "[requires] condition specified, with gotmpl key",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           nil,
+							ignoreSystemEnv: true,
+							Requires: []*Requires{
+								{
+									GoTmpl: fn.New(`eq 5 5`),
+								},
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+
+		{
+			name: "[requires] condition specified, with sh key",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           nil,
+							ignoreSystemEnv: true,
+							Requires: []*Requires{
+								{
+									Sh: fn.New(`echo hello`),
+								},
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+
+		{
+			name: "[unhappy/requires] condition specified, with sh key",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           nil,
+							ignoreSystemEnv: true,
+							Requires: []*Requires{
+								{
+									Sh: fn.New(`echo hello && exit 1`),
+								},
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands:   []CommandJson{},
+			},
+			wantErr: true,
+		},
+	}
+
+	testEnviroments := []test{
+		{
+			name: "[unhappy/env] required env, not provided",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Env: EnvVar{
+								"hello": map[string]any{
+									"required": true,
+								},
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name: "[env] required env, provided",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Env: EnvVar{
+								"hello": map[string]any{
+									"required": true,
+								},
+							},
+							DotEnv: []string{
+								dotenvTestFile.Name(),
+							},
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Environ: []string{
+					"hello=world",
+				},
+				Commands: []CommandJson{},
+			},
+			wantErr: false,
+		},
+	}
+
+	tests := []test{
+		{
+			name: "[shell] if not specified, defaults to [sh, -c]",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           nil,
+							ignoreSystemEnv: true,
+							Dir:             fn.New("."),
+							Commands:        nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: ".",
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[shell] if specified, must be acknowledged",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           []string{"python", "-c"},
+							ignoreSystemEnv: true,
+							Dir:             fn.New("."),
+							Commands:        nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"python", "-c"},
+				WorkingDir: ".",
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[env] key: value",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							Shell:           []string{"sh", "-c"},
+							ignoreSystemEnv: true,
+							Env: map[string]any{
+								"hello": "hi",
+								"k1":    1,
+							},
+							Dir:      fn.New("."),
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell: []string{"sh", "-c"},
+				Environ: []string{
+					"hello=hi",
+					"k1=1",
+				},
+				WorkingDir: ".",
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[env] key: JSON object format",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Env: map[string]any{
+								"hello": map[string]any{
+									"sh": "echo hi",
+								},
+							},
+							Dir:      fn.New("."),
+							Commands: nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell: []string{"sh", "-c"},
+				Environ: []string{
+					"hello=hi",
+				},
+				WorkingDir: ".",
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[unhappy/env] JSON object format [must throw err, when] sh key does not exist in value",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Env: map[string]any{
+								"k1": map[string]any{
+									"asdfasf": "asdfad",
+								},
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[unhappy/env] JSON object format [must throw err, when] sh (key)'s value is not a string",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Env: map[string]any{
+								"k1": map[string]any{
+									"sh": []string{"asdfsadf"},
+								},
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[dotenv] loads environment from given file",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							DotEnv: []string{
+								dotenvTestFile.Name(),
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Environ: []string{
+					"hello=world", // from dotenv
+				},
+				Commands: []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[unhappy/dotenv] throws err, when file does not exist",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							DotEnv: []string{
+								"/tmp/env-aasfksadjfkl",
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[unhappy/dotenv] throws err, when filepath exists [but] is not a file (might be a directory or something else)",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							DotEnv: []string{
+								"/tmp",
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[working_dir] if not specified, should be current working directory",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Commands:        nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[working_dir] when specified, must be acknowledged",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Dir:             fn.New("/tmp"),
+							Commands:        nil,
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: "/tmp",
+				Commands:   []CommandJson{},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[unhappy/working_dir]  must throw err, when directory does not exist",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Dir:             fn.New("/tmp/xsdfjasdfkjdskfjasl"),
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[unhappy/working_dir] must throw err, when directory specified is not a directory (might be something else, or a file)",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Dir:             fn.New(filepath.Join(fn.Must(os.Getwd()), "task.go")),
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[commands] string commands: single line",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Commands: []any{
+								"echo hello",
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands: []CommandJson{
+					{Command: "echo hello"},
+				},
+			},
+			wantErr: false,
+		},
+
+		{
+			name: "[commands] string commands: multiline",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Commands: []any{
+								`
+echo "hello"
+echo "hi"
+`,
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands: []CommandJson{
+					{
+						Command: `
+echo "hello"
+echo "hi"
+`,
+					},
+				},
+			},
+			wantErr: false,
+		},
+
+		{
+			name: "[commands] JSON commands",
+			args: args{
+				ctx: nil,
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Commands: []any{
+								"echo i will call hello, now",
+								map[string]any{
+									"run": "hello",
+								},
+							},
+						},
+						"hello": {
+							ignoreSystemEnv: true,
+							Commands: []any{
+								"echo hello everyone",
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			want: &ParsedTask{
+				Shell:      []string{"sh", "-c"},
+				WorkingDir: fn.Must(os.Getwd()),
+				Commands: []CommandJson{
+					{Command: "echo i will call hello, now"},
+					{Run: "hello"},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "[unhappy/commands] JSON commands [must throw err, when] run target does not exist",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{
+						"test": {
+							ignoreSystemEnv: true,
+							Commands: []any{
+								"echo i will call hello, now",
+								map[string]any{
+									"run": "hello",
+								},
+							},
+						},
+					},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+		{
+			name: "[unhappy/runfile] target task does not exist",
+			args: args{
+				rf: &Runfile{
+					Tasks: map[string]Task{},
+				},
+				taskName: "test",
+			},
+			wantErr: true,
+		},
+	}
+
+	tests = append(tests, testRequires...)
+	tests = append(tests, testEnviroments...)
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseTask(context.TODO(), tt.args.rf, tt.args.taskName)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ParseTask() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			// if !reflect.DeepEqual(got, tt.want) {
+			if !tt.wantErr {
+				if !areEqual(t, got, tt.want) {
+					t.Errorf("ParseTask():> \n\tgot:\t%v,\n\twant:\t%v", got, tt.want)
+				}
+			}
+		})
+	}
+}
diff --git a/pkg/runfile/task.go b/pkg/runfile/task.go
new file mode 100644
index 0000000..62b2e91
--- /dev/null
+++ b/pkg/runfile/task.go
@@ -0,0 +1,53 @@
+package runfile
+
+// Only one of the fields must be set
+type Requires struct {
+	Sh     *string `json:"sh,omitempty"`
+	GoTmpl *string `json:"gotmpl,omitempty"`
+}
+
+/*
+EnvVar Values could take multiple forms:
+- my_key: "value"
+or
+  - my_key:
+    sh: "echo hello hi"
+
+Object values with `sh` key, such that the output of this command will be the value of the top-level key
+*/
+type EnvVar map[string]any
+
+type Task struct {
+	// Shell in which above commands will be executed
+	// Default: ["sh", "-c"]
+	/* Common Usecases could be:
+	   - ["bash", "-c"]
+	   - ["python", "-c"]
+	   - ["node", "-e"]
+	*/
+	Shell []string `json:"shell"`
+
+	// load env vars from [.env](https://www.google.com/search?q=sample+dotenv+files&udm=2) files
+	DotEnv []string `json:"dotenv"`
+
+	// working directory for the task
+	Dir *string `json:"dir,omitempty"`
+
+	Env EnvVar `json:"env,omitempty"`
+
+	// this field is for testing purposes only
+	ignoreSystemEnv bool `json:"-"`
+
+	Requires []*Requires `json:"requires,omitempty"`
+
+	// List of commands to be executed in given shell (default: sh)
+	// can take multiple forms
+	//   - simple string
+	//   - a json object with key `run`, signifying other tasks to run
+	Commands []any `json:"cmd"`
+}
+
+type CommandJson struct {
+	Command string
+	Run     string `json:"run"`
+}
diff --git a/pkg/runfile/type.go b/pkg/runfile/type.go
index f62304d..4333a64 100644
--- a/pkg/runfile/type.go
+++ b/pkg/runfile/type.go
@@ -1,15 +1,153 @@
 package runfile
 
-type RunFile struct {
-	Version string
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+	"text/template"
 
-	Tasks map[string]TaskSpec `json:"tasks"`
+	sprig "github.com/go-task/slim-sprig/v3"
+	fn "github.com/nxtcoder17/runfile/pkg/functions"
+)
+
+type EvaluationArgs struct {
+	Shell []string
+	Env   map[string]string
+}
+
+func ToEnviron(m map[string]string) []string {
+	results := os.Environ()
+	for k, v := range m {
+		results = append(results, fmt.Sprintf("%s=%v", k, v))
+	}
+	return results
+}
+
+type EnvKV struct {
+	Key string
+
+	Value  *string `json:"value"`
+	Sh     *string `json:"sh"`
+	GoTmpl *string `json:"gotmpl"`
 }
 
-type TaskSpec struct {
-	// load env vars from [.env](https://www.google.com/search?q=sample+dotenv+files&udm=2) files
-	DotEnv   []string       `json:"dotenv"`
-	Env      map[string]any `json:"env"`
-	Commands []string       `json:"cmd"`
-	Shell    []string       `json:"shell"`
+func (ejv EnvKV) Parse(ctx context.Context, args EvaluationArgs) (*string, error) {
+	switch {
+	case ejv.Value != nil:
+		{
+			return ejv.Value, nil
+		}
+	case ejv.Sh != nil:
+		{
+			value := new(bytes.Buffer)
+
+			cmd := createCommand(ctx, cmdArgs{
+				shell:  args.Shell,
+				env:    ToEnviron(args.Env),
+				cmd:    *ejv.Sh,
+				stdout: value,
+			})
+			if err := cmd.Run(); err != nil {
+				return nil, err
+			}
+
+			return fn.New(strings.TrimSpace(value.String())), nil
+		}
+	case ejv.GoTmpl != nil:
+		{
+			t := template.New(ejv.Key).Funcs(sprig.FuncMap())
+			t, err := t.Parse(fmt.Sprintf(`{{ %s }}`, *ejv.GoTmpl))
+			if err != nil {
+				return nil, err
+			}
+
+			value := new(bytes.Buffer)
+			if err := t.ExecuteTemplate(value, ejv.Key, map[string]string{}); err != nil {
+				return nil, err
+			}
+
+			return fn.New(strings.TrimSpace(value.String())), nil
+		}
+	default:
+		{
+			return nil, fmt.Errorf("failed to parse, unknown format, one of [value, sh, gotmpl] must be set")
+		}
+	}
+}
+
+func parseEnvVars(ctx context.Context, ev EnvVar, args EvaluationArgs) (map[string]string, error) {
+	env := make(map[string]string, len(ev))
+	for k, v := range ev {
+		switch v := v.(type) {
+		case string:
+			env[k] = v
+		case map[string]any:
+			b, err := json.Marshal(v)
+			if err != nil {
+				return nil, err
+			}
+
+			var envAsJson struct {
+				*EnvKV
+				Required bool
+				Default  *EnvKV
+			}
+
+			if err := json.Unmarshal(b, &envAsJson); err != nil {
+				return nil, err
+			}
+
+			switch {
+			case envAsJson.Required:
+				{
+					isDefined := false
+					if _, ok := os.LookupEnv(k); ok {
+						isDefined = true
+					}
+
+					if !isDefined {
+						if _, ok := args.Env[k]; ok {
+							isDefined = true
+						}
+					}
+
+					if !isDefined {
+						return nil, fmt.Errorf("env: %q, not defined", k)
+					}
+				}
+
+			case envAsJson.EnvKV != nil:
+				{
+					envAsJson.Key = k
+					s, err := envAsJson.EnvKV.Parse(ctx, args)
+					if err != nil {
+						return nil, err
+					}
+					env[k] = *s
+				}
+
+			case envAsJson.Default != nil:
+				{
+					envAsJson.Default.Key = k
+					s, err := envAsJson.Default.Parse(ctx, args)
+					if err != nil {
+						return nil, err
+					}
+					env[k] = *s
+				}
+			default:
+				{
+					return nil, fmt.Errorf("either required, value, sh, gotmpl or default, must be defined")
+				}
+			}
+
+		default:
+			env[k] = fmt.Sprintf("%v", v)
+		}
+	}
+
+	return env, nil
 }