diff --git a/.golangci.yml b/.golangci.yml
index a84a30c4..ce481ee2 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -126,7 +126,7 @@ linters:
     #- exhaustruct # [highly recommend to enable] checks if all structure fields are initialized
     #- ginkgolinter # [if you use ginkgo/gomega] enforces standards of using ginkgo and gomega
     #- godox # detects usage of FIXME, TODO and other keywords inside comments
-    #- goheader # checks is file header matches to pattern
+    - goheader # checks that each file starts with the project license header
     #- inamedparam # [great idea, but too strict, need to ignore a lot of cases by default] reports interfaces with unnamed method parameters
     #- interfacebloat # checks the number of methods inside an interface
     #- ireturn # accept interfaces, return concrete types
@@ -323,6 +323,32 @@ linters:
     gocyclo:
       min-complexity: 35
 
+    goheader:
+      # Every source file must open with the GPL-3.0-only header carried by the
+      # original shell implementation (see the `legacy` branch). The year is pinned
+      # to the project's inception (2021) to stay consistent with the shell sources
+      # still shipped under internal/inside-distrobox/assets, so no {{ YEAR }}
+      # placeholder is used here.
+      template: |-
+        SPDX-License-Identifier: GPL-3.0-only
+
+        This file is part of the distrobox project:
+           https://github.com/89luca89/distrobox
+
+        Copyright (C) 2021 distrobox contributors
+
+        distrobox is free software; you can redistribute it and/or modify it
+        under the terms of the GNU General Public License version 3
+        as published by the Free Software Foundation.
+
+        distrobox is distributed in the hope that it will be useful, but
+        WITHOUT ANY WARRANTY; without even the implied warranty of
+        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+        General Public License for more details.
+
+        You should have received a copy of the GNU General Public License
+        along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
     govet:
       # Enable all analyzers.
       # Default: false
diff --git a/cmd/distrobox/main.go b/cmd/distrobox/main.go
index 9fb5ef64..e9a2e0c9 100644
--- a/cmd/distrobox/main.go
+++ b/cmd/distrobox/main.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package main
 
 import (
diff --git a/internal/cli/assemble.go b/internal/cli/assemble.go
index 4f56049b..d299515e 100644
--- a/internal/cli/assemble.go
+++ b/internal/cli/assemble.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/assemble_internal_test.go b/internal/cli/assemble_internal_test.go
index 12daef93..64f05f0c 100644
--- a/internal/cli/assemble_internal_test.go
+++ b/internal/cli/assemble_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import "testing"
diff --git a/internal/cli/compatibility.go b/internal/cli/compatibility.go
index 3899eef8..ec44dc22 100644
--- a/internal/cli/compatibility.go
+++ b/internal/cli/compatibility.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/compatibility_internal_test.go b/internal/cli/compatibility_internal_test.go
index f149b149..7b107ff1 100644
--- a/internal/cli/compatibility_internal_test.go
+++ b/internal/cli/compatibility_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/completion.go b/internal/cli/completion.go
index c40ed298..29b99625 100644
--- a/internal/cli/completion.go
+++ b/internal/cli/completion.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/create.go b/internal/cli/create.go
index a2c29214..b0b55d68 100644
--- a/internal/cli/create.go
+++ b/internal/cli/create.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/enter.go b/internal/cli/enter.go
index fa0775c7..f4f35539 100644
--- a/internal/cli/enter.go
+++ b/internal/cli/enter.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/enter_internal_test.go b/internal/cli/enter_internal_test.go
index c52d91b0..ebcde30c 100644
--- a/internal/cli/enter_internal_test.go
+++ b/internal/cli/enter_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/ephemeral.go b/internal/cli/ephemeral.go
index 5b5b245a..93382218 100644
--- a/internal/cli/ephemeral.go
+++ b/internal/cli/ephemeral.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/ephemeral_internal_test.go b/internal/cli/ephemeral_internal_test.go
index d6e0a14f..500ffa4b 100644
--- a/internal/cli/ephemeral_internal_test.go
+++ b/internal/cli/ephemeral_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/generate-entry.go b/internal/cli/generate-entry.go
index 92b1d769..23e8f2a9 100644
--- a/internal/cli/generate-entry.go
+++ b/internal/cli/generate-entry.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/list.go b/internal/cli/list.go
index 49445ae0..c23b4d36 100644
--- a/internal/cli/list.go
+++ b/internal/cli/list.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/parse.go b/internal/cli/parse.go
index 6eae1c98..db9a0716 100644
--- a/internal/cli/parse.go
+++ b/internal/cli/parse.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/parse_internal_test.go b/internal/cli/parse_internal_test.go
index 5e76eae5..2975d9bb 100644
--- a/internal/cli/parse_internal_test.go
+++ b/internal/cli/parse_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/rm.go b/internal/cli/rm.go
index 21b1410d..1f6a63b8 100644
--- a/internal/cli/rm.go
+++ b/internal/cli/rm.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/root.go b/internal/cli/root.go
index 59c8582b..f5e18ca7 100644
--- a/internal/cli/root.go
+++ b/internal/cli/root.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/root_internal_test.go b/internal/cli/root_internal_test.go
index 78006d5c..2ab659ac 100644
--- a/internal/cli/root_internal_test.go
+++ b/internal/cli/root_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/stop.go b/internal/cli/stop.go
index b43c6ff3..851076da 100644
--- a/internal/cli/stop.go
+++ b/internal/cli/stop.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/cli/upgrade.go b/internal/cli/upgrade.go
index 6ee45423..4c135fc6 100644
--- a/internal/cli/upgrade.go
+++ b/internal/cli/upgrade.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package cli
 
 import (
diff --git a/internal/inside-distrobox/scripts.go b/internal/inside-distrobox/scripts.go
index e16b7677..63f684de 100644
--- a/internal/inside-distrobox/scripts.go
+++ b/internal/inside-distrobox/scripts.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package insidedistrobox
 
 import (
diff --git a/internal/inside-distrobox/scripts_test.go b/internal/inside-distrobox/scripts_test.go
index 84d616ec..8471a7eb 100644
--- a/internal/inside-distrobox/scripts_test.go
+++ b/internal/inside-distrobox/scripts_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package insidedistrobox_test
 
 import (
diff --git a/internal/rootful/rootful.go b/internal/rootful/rootful.go
index 238d67b3..65e659e5 100644
--- a/internal/rootful/rootful.go
+++ b/internal/rootful/rootful.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 // Package rootful provides utilities for running operations that require
 // root privileges via a configurable sudo command.
 package rootful
diff --git a/internal/rootful/rootful_internal_test.go b/internal/rootful/rootful_internal_test.go
index 56ec2086..254a8a4f 100644
--- a/internal/rootful/rootful_internal_test.go
+++ b/internal/rootful/rootful_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package rootful
 
 import (
diff --git a/internal/userenv/user_environment.go b/internal/userenv/user_environment.go
index a10bca91..bfea6e38 100644
--- a/internal/userenv/user_environment.go
+++ b/internal/userenv/user_environment.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package userenv
 
 import (
diff --git a/internal/userenv/user_environment_test.go b/internal/userenv/user_environment_test.go
index 7e970e0e..86d3547a 100644
--- a/internal/userenv/user_environment_test.go
+++ b/internal/userenv/user_environment_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package userenv_test
 
 import (
diff --git a/pkg/commands/assemble.go b/pkg/commands/assemble.go
index ac0ff350..8b98fcdd 100644
--- a/pkg/commands/assemble.go
+++ b/pkg/commands/assemble.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/assemble_test.go b/pkg/commands/assemble_test.go
index fcbc414e..3af02830 100644
--- a/pkg/commands/assemble_test.go
+++ b/pkg/commands/assemble_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/create.go b/pkg/commands/create.go
index 5f93083d..9f08a66d 100644
--- a/pkg/commands/create.go
+++ b/pkg/commands/create.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/create_test.go b/pkg/commands/create_test.go
index ebd0d8ce..93a53d27 100644
--- a/pkg/commands/create_test.go
+++ b/pkg/commands/create_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/distro_icons.go b/pkg/commands/distro_icons.go
index f04c4375..47333ec3 100644
--- a/pkg/commands/distro_icons.go
+++ b/pkg/commands/distro_icons.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import "strings"
diff --git a/pkg/commands/enter.go b/pkg/commands/enter.go
index 7813dcc8..952bd903 100644
--- a/pkg/commands/enter.go
+++ b/pkg/commands/enter.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/ephemeral.go b/pkg/commands/ephemeral.go
index 9ce97311..ae75de1e 100644
--- a/pkg/commands/ephemeral.go
+++ b/pkg/commands/ephemeral.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/ephemeral_internal_test.go b/pkg/commands/ephemeral_internal_test.go
index 27c85779..ee9ed011 100644
--- a/pkg/commands/ephemeral_internal_test.go
+++ b/pkg/commands/ephemeral_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/ephemeral_test.go b/pkg/commands/ephemeral_test.go
index d5284382..746cc180 100644
--- a/pkg/commands/ephemeral_test.go
+++ b/pkg/commands/ephemeral_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/generate_entry.go b/pkg/commands/generate_entry.go
index 5fb1e9fd..f62bf7c0 100644
--- a/pkg/commands/generate_entry.go
+++ b/pkg/commands/generate_entry.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/generate_entry_internal_test.go b/pkg/commands/generate_entry_internal_test.go
index ff02eddc..2014dcfb 100644
--- a/pkg/commands/generate_entry_internal_test.go
+++ b/pkg/commands/generate_entry_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/generate_entry_test.go b/pkg/commands/generate_entry_test.go
index 262bdf8f..78c4a742 100644
--- a/pkg/commands/generate_entry_test.go
+++ b/pkg/commands/generate_entry_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/list.go b/pkg/commands/list.go
index 7e0298e9..357767aa 100644
--- a/pkg/commands/list.go
+++ b/pkg/commands/list.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/list_test.go b/pkg/commands/list_test.go
index 88c05e19..7203a5c8 100644
--- a/pkg/commands/list_test.go
+++ b/pkg/commands/list_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/rm.go b/pkg/commands/rm.go
index 044669fe..bde9e7ac 100644
--- a/pkg/commands/rm.go
+++ b/pkg/commands/rm.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/rm_test.go b/pkg/commands/rm_test.go
index 3c973421..e36b85c9 100644
--- a/pkg/commands/rm_test.go
+++ b/pkg/commands/rm_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/commands/stop.go b/pkg/commands/stop.go
index 0097c42a..c82bf433 100644
--- a/pkg/commands/stop.go
+++ b/pkg/commands/stop.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/upgrade.go b/pkg/commands/upgrade.go
index ad1db3b8..d987ae86 100644
--- a/pkg/commands/upgrade.go
+++ b/pkg/commands/upgrade.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands
 
 import (
diff --git a/pkg/commands/upgrade_test.go b/pkg/commands/upgrade_test.go
index 2e8fc6f0..6baea5ec 100644
--- a/pkg/commands/upgrade_test.go
+++ b/pkg/commands/upgrade_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package commands_test
 
 import (
diff --git a/pkg/config/config.go b/pkg/config/config.go
index 8b5f1f32..104a06d2 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package config
 
 import (
diff --git a/pkg/config/config_internal_test.go b/pkg/config/config_internal_test.go
index 7a5b59df..597fa918 100644
--- a/pkg/config/config_internal_test.go
+++ b/pkg/config/config_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package config
 
 import (
diff --git a/pkg/config/config_test.go b/pkg/config/config_test.go
index a3058a64..02c813e3 100644
--- a/pkg/config/config_test.go
+++ b/pkg/config/config_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package config_test
 
 import (
diff --git a/pkg/containermanager/bindmount_internal_test.go b/pkg/containermanager/bindmount_internal_test.go
index 95a1d3d0..5dfa443c 100644
--- a/pkg/containermanager/bindmount_internal_test.go
+++ b/pkg/containermanager/bindmount_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package containermanager
 
 import "testing"
diff --git a/pkg/containermanager/containermanager.go b/pkg/containermanager/containermanager.go
index d7d89dbf..320dfc1a 100644
--- a/pkg/containermanager/containermanager.go
+++ b/pkg/containermanager/containermanager.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package containermanager
 
 import (
diff --git a/pkg/containermanager/containermanager_test.go b/pkg/containermanager/containermanager_test.go
index ca1032d9..f00e0124 100644
--- a/pkg/containermanager/containermanager_test.go
+++ b/pkg/containermanager/containermanager_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package containermanager_test
 
 import (
diff --git a/pkg/containermanager/providers/autodetect.go b/pkg/containermanager/providers/autodetect.go
index 707e6051..018f1408 100644
--- a/pkg/containermanager/providers/autodetect.go
+++ b/pkg/containermanager/providers/autodetect.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/autodetect_test.go b/pkg/containermanager/providers/autodetect_test.go
index 2676eec1..dab59129 100644
--- a/pkg/containermanager/providers/autodetect_test.go
+++ b/pkg/containermanager/providers/autodetect_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers_test
 
 import (
diff --git a/pkg/containermanager/providers/clone_internal_test.go b/pkg/containermanager/providers/clone_internal_test.go
index d6a1cde3..d94bf266 100644
--- a/pkg/containermanager/providers/clone_internal_test.go
+++ b/pkg/containermanager/providers/clone_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/docker.go b/pkg/containermanager/providers/docker.go
index 5e1ceeb2..edfcb8b2 100644
--- a/pkg/containermanager/providers/docker.go
+++ b/pkg/containermanager/providers/docker.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/docker_internal_test.go b/pkg/containermanager/providers/docker_internal_test.go
index 6b0b8409..ef82044f 100644
--- a/pkg/containermanager/providers/docker_internal_test.go
+++ b/pkg/containermanager/providers/docker_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/podman.go b/pkg/containermanager/providers/podman.go
index 1c841b19..b891bfc6 100644
--- a/pkg/containermanager/providers/podman.go
+++ b/pkg/containermanager/providers/podman.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/podman_internal_test.go b/pkg/containermanager/providers/podman_internal_test.go
index 21785bcb..b881a56f 100644
--- a/pkg/containermanager/providers/podman_internal_test.go
+++ b/pkg/containermanager/providers/podman_internal_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import (
diff --git a/pkg/containermanager/providers/sleeps.go b/pkg/containermanager/providers/sleeps.go
index 40ba34e8..3139e9ac 100644
--- a/pkg/containermanager/providers/sleeps.go
+++ b/pkg/containermanager/providers/sleeps.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package providers
 
 import "time"
diff --git a/pkg/internal/testutil/mock_containermanager.go b/pkg/internal/testutil/mock_containermanager.go
index d6b29cd4..476ca9cd 100644
--- a/pkg/internal/testutil/mock_containermanager.go
+++ b/pkg/internal/testutil/mock_containermanager.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package testutil
 
 import (
diff --git a/pkg/manifest/parse.go b/pkg/manifest/parse.go
index b1a16002..6a021539 100644
--- a/pkg/manifest/parse.go
+++ b/pkg/manifest/parse.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package manifest
 
 import (
diff --git a/pkg/manifest/parse_test.go b/pkg/manifest/parse_test.go
index b915051c..2a423d0b 100644
--- a/pkg/manifest/parse_test.go
+++ b/pkg/manifest/parse_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package manifest_test
 
 import (
diff --git a/pkg/ui/colors.go b/pkg/ui/colors.go
index bebc695f..fbae6d2b 100644
--- a/pkg/ui/colors.go
+++ b/pkg/ui/colors.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package ui
 
 const (
diff --git a/pkg/ui/printer.go b/pkg/ui/printer.go
index 3c7c805e..022e9102 100644
--- a/pkg/ui/printer.go
+++ b/pkg/ui/printer.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package ui
 
 import (
diff --git a/pkg/ui/progress.go b/pkg/ui/progress.go
index 5aa625d9..1e36c8f7 100644
--- a/pkg/ui/progress.go
+++ b/pkg/ui/progress.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package ui
 
 import (
diff --git a/pkg/ui/prompt.go b/pkg/ui/prompt.go
index fec194d2..28caecbd 100644
--- a/pkg/ui/prompt.go
+++ b/pkg/ui/prompt.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package ui
 
 import (
diff --git a/pkg/ui/prompt_test.go b/pkg/ui/prompt_test.go
index 486df565..75aff952 100644
--- a/pkg/ui/prompt_test.go
+++ b/pkg/ui/prompt_test.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package ui_test
 
 import (
diff --git a/pkg/version/version.go b/pkg/version/version.go
index 9b8fd894..84316e89 100644
--- a/pkg/version/version.go
+++ b/pkg/version/version.go
@@ -1,3 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-only
+//
+// This file is part of the distrobox project:
+//    https://github.com/89luca89/distrobox
+//
+// Copyright (C) 2021 distrobox contributors
+//
+// distrobox is free software; you can redistribute it and/or modify it
+// under the terms of the GNU General Public License version 3
+// as published by the Free Software Foundation.
+//
+// distrobox is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with distrobox; if not, see <http://www.gnu.org/licenses/>.
+
 package version
 
 // Version is set at build time via -ldflags.