diff --git a/atlasaction/action.go b/atlasaction/action.go
index 957d98bd..873eff97 100644
--- a/atlasaction/action.go
+++ b/atlasaction/action.go
@@ -1240,26 +1240,35 @@ func RenderTemplate(name string, data any) (string, error) {
 	return buf.String(), nil
 }
 
-// toEnvVar converts the given string to an environment variable name.
-func toEnvVar(s string) string {
+// toEnvName converts the given string to an environment variable name.
+func toEnvName(s string) string {
 	return strings.ToUpper(strings.NewReplacer(
 		" ", "_", "-", "_", "/", "_",
 	).Replace(s))
 }
 
-// writeBashEnv writes the given name and value to the bash environment file.
-func writeBashEnv(path, name, value string) error {
+// toInputVarName converts the given string to an input variable name.
+func toInputVarName(input string) string {
+	return fmt.Sprintf("ATLAS_INPUT_%s", toEnvName(input))
+}
+
+// toOutputVar converts the given values to an output variable.
+// The action and output are used to create the output variable name with the format:
+// ATLAS_OUTPUT_<ACTION>_<OUTPUT>="<value>"
+func toOutputVar(action, output, value string) string {
+	return fmt.Sprintf("ATLAS_OUTPUT_%s=%q", toEnvName(action+"_"+output), value)
+}
+
+// fprintln writes the given values to the file using fmt.Fprintln.
+func fprintln(name string, val ...any) error {
 	// Write the output to a file.
-	f, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	f, err := os.OpenFile(name, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
 		return fmt.Errorf("failed to open file: %w", err)
 	}
 	defer f.Close()
-	_, err = fmt.Fprintf(f, "export %s=%q\n", name, value)
-	if err != nil {
-		return err
-	}
-	return nil
+	_, err = fmt.Fprintln(f, val...)
+	return err
 }
 
 // commentMarker creates a hidden marker to identify the comment as one created by this action.
diff --git a/atlasaction/bitbucket.go b/atlasaction/bitbucket.go
index 7026a91e..d2add496 100644
--- a/atlasaction/bitbucket.go
+++ b/atlasaction/bitbucket.go
@@ -80,7 +80,7 @@ func (a *bbPipe) GetTriggerContext(context.Context) (*TriggerContext, error) {
 
 // GetInput implements the Action interface.
 func (a *bbPipe) GetInput(name string) string {
-	return strings.TrimSpace(a.getenv("ATLAS_INPUT_" + toEnvVar(name)))
+	return strings.TrimSpace(a.getenv(toInputVarName(name)))
 }
 
 // SetOutput implements Action.
@@ -104,11 +104,11 @@ func (a *bbPipe) SetOutput(name, value string) {
 		a.Errorf("failed to create output directory %s: %v", dir, err)
 		return
 	}
-	cmd := a.getenv("ATLAS_ACTION_COMMAND")
-	err := writeBashEnv(filepath.Join(dir, "outputs.sh"), toEnvVar(
-		fmt.Sprintf("ATLAS_OUTPUT_%s_%s", cmd, name)), value)
+	outputs := filepath.Join(dir, "outputs.sh")
+	err := fprintln(outputs,
+		"export", toOutputVar(a.getenv("ATLAS_ACTION_COMMAND"), name, value))
 	if err != nil {
-		a.Errorf("failed to write output to file %s: %v", dir, err)
+		a.Errorf("failed to write output to file %s: %v", outputs, err)
 	}
 }
 
diff --git a/atlasaction/circleci_action.go b/atlasaction/circleci_action.go
index ae3e5d55..5184474a 100644
--- a/atlasaction/circleci_action.go
+++ b/atlasaction/circleci_action.go
@@ -38,19 +38,22 @@ func (a *circleCIOrb) Getenv(key string) string {
 
 // GetInput implements the Action interface.
 func (a *circleCIOrb) GetInput(name string) string {
-	return strings.TrimSpace(a.getenv(toEnvVar("INPUT_" + name)))
+	v := a.getenv(toInputVarName(name))
+	if v == "" {
+		// TODO: Remove this fallback once all the actions are updated.
+		v = a.getenv(toEnvName("INPUT_" + name))
+	}
+	return strings.TrimSpace(v)
 }
 
 // SetOutput implements the Action interface.
 func (a *circleCIOrb) SetOutput(name, value string) {
 	if bashEnv := a.getenv("BASH_ENV"); bashEnv != "" {
-		cmd := a.getenv("ATLAS_ACTION_COMMAND")
-		err := writeBashEnv(bashEnv, toEnvVar(
-			fmt.Sprintf("ATLAS_OUTPUT_%s_%s", cmd, name)), value)
+		err := fprintln(bashEnv,
+			"export", toOutputVar(a.getenv("ATLAS_ACTION_COMMAND"), name, value))
 		if err != nil {
-			a.Fatalf("failed to write env to file %s: %v", bashEnv, err)
+			a.Fatalf("failed to write output to file %s: %v", bashEnv, err)
 		}
-		return
 	}
 }
 
diff --git a/atlasaction/circleci_action_test.go b/atlasaction/circleci_action_test.go
index 0775993b..a7c0efc6 100644
--- a/atlasaction/circleci_action_test.go
+++ b/atlasaction/circleci_action_test.go
@@ -60,7 +60,7 @@ func Test_circleCIOrb_GetTriggerContext(t *testing.T) {
 func TestCircleCI(t *testing.T) {
 	var (
 		actions = "actions"
-		output  = filepath.Join(actions, "output.txt")
+		output  = filepath.Join(actions, "output.sh")
 	)
 	wd, err := os.Getwd()
 	require.NoError(t, err)
@@ -75,7 +75,7 @@ func TestCircleCI(t *testing.T) {
 			e.Setenv("CIRCLECI", "true")
 			e.Setenv("CIRCLE_PROJECT_REPONAME", "atlas-orb")
 			e.Setenv("CIRCLE_SHA1", "1234567890")
-			e.Setenv("BASH_ENV", filepath.Join(dir, "output.txt"))
+			e.Setenv("BASH_ENV", filepath.Join(dir, "output.sh"))
 			return nil
 		},
 		Cmds: map[string]func(ts *testscript.TestScript, neg bool, args []string){
diff --git a/atlasaction/gitlab_ci.go b/atlasaction/gitlab_ci.go
index 78dd4c5b..d490cd9d 100644
--- a/atlasaction/gitlab_ci.go
+++ b/atlasaction/gitlab_ci.go
@@ -8,7 +8,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"os"
 	"slices"
 	"strconv"
 	"strings"
@@ -40,17 +39,15 @@ func (a *gitlabCI) Getenv(key string) string {
 
 // GetInput implements the Action interface.
 func (a *gitlabCI) GetInput(name string) string {
-	return strings.TrimSpace(a.getenv(toEnvVar("ATLAS_INPUT_" + name)))
+	return strings.TrimSpace(a.getenv(toInputVarName(name)))
 }
 
 // SetOutput implements the Action interface.
 func (a *gitlabCI) SetOutput(name, value string) {
-	f, err := os.OpenFile(".env", os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0600)
+	err := fprintln(".env", toOutputVar(a.getenv("ATLAS_ACTION_COMMAND"), name, value))
 	if err != nil {
-		return
+		a.Errorf("failed to write output to file .env: %v", err)
 	}
-	defer f.Close()
-	fmt.Fprintf(f, "%s=%s\n", name, value)
 }
 
 // GetTriggerContext implements the Action interface.
diff --git a/atlasaction/testdata/circleci/migrate-lint.txtar b/atlasaction/testdata/circleci/migrate-lint.txtar
index a6041936..11abcb39 100644
--- a/atlasaction/testdata/circleci/migrate-lint.txtar
+++ b/atlasaction/testdata/circleci/migrate-lint.txtar
@@ -1,26 +1,26 @@
 # Mock the atlas command outputs
 env ATLAS_PATH=$MOCK_ATLAS TEST_BATCH=./migrate-lint
 # Setup the action input variables
-env INPUT_CONFIG=file://testdata/config/atlas.hcl
-env INPUT_ENV=test
-env INPUT_DIR_NAME=pupisu
-env INPUT_TAG=staging
-env INPUT_VARS='{"var1":"value1","var2":"value2"}'
-env INPUT_DIR=file://testdata/migrations
-env INPUT_DEV_URL=sqlite://file?mode=memory
-env INPUT_RUN=example
+env ATLAS_INPUT_CONFIG=file://testdata/config/atlas.hcl
+env ATLAS_INPUT_ENV=test
+env ATLAS_INPUT_DIR_NAME=pupisu
+env ATLAS_INPUT_TAG=staging
+env ATLAS_INPUT_VARS='{"var1":"value1","var2":"value2"}'
+env ATLAS_INPUT_DIR=file://testdata/migrations
+env ATLAS_INPUT_DEV_URL=sqlite://file?mode=memory
+env ATLAS_INPUT_RUN=example
 
 # The action's output should append the existing outputs
-cp output-pre.txt actions/output.txt
+cp output-pre.sh actions/output.sh
 atlas-action --action=migrate/lint
-output output.txt
+output output.sh
 
 -- migrate-lint/1/args --
 migrate lint -w --context {"repo":"atlas-orb","path":"file://testdata/migrations","commit":"1234567890"} --env test --config file://testdata/config/atlas.hcl --dev-url sqlite://file?mode=memory --dir file://testdata/migrations --base atlas://pupisu?tag=staging --var var1=value1 --var var2=value2 --format {{ json . }}
 -- migrate-lint/1/stdout --
 {"URL":"https://migration-lint-report-url"}
--- output-pre.txt --
+-- output-pre.sh --
 export FOO=bar
--- output.txt --
+-- output.sh --
 export FOO=bar
 export ATLAS_OUTPUT_MIGRATE_LINT_REPORT_URL="https://migration-lint-report-url"
diff --git a/atlasaction/testdata/gitlab/schema-plan-approve.txtar b/atlasaction/testdata/gitlab/schema-plan-approve.txtar
index 7741ce1c..7d6318a4 100644
--- a/atlasaction/testdata/gitlab/schema-plan-approve.txtar
+++ b/atlasaction/testdata/gitlab/schema-plan-approve.txtar
@@ -7,7 +7,7 @@ stdout 'No schema plan found'
 
 # One pending plan.
 atlas-action --action=schema/plan/approve
-output expected-output.env
+output .env.expected-output
 
 # Multiple pending plans.
 ! atlas-action --action=schema/plan/approve
@@ -15,12 +15,12 @@ stdout 'No plan URL provided, searching for the pending plan'
 stdout 'Found schema plan: atlas://plans/1234'
 stdout 'Found schema plan: atlas://plans/5678'
 stdout 'found multiple schema plans, please approve or delete the existing plans'
-output expected-output.env
+output .env.expected-output
 
--- expected-output.env --
-link=https://test.atlasgo.cloud/schemas/123/plans/456
-plan=atlas://plans/1234
-status=
+-- .env.expected-output --
+ATLAS_OUTPUT_SCHEMA_PLAN_APPROVE_LINK="https://test.atlasgo.cloud/schemas/123/plans/456"
+ATLAS_OUTPUT_SCHEMA_PLAN_APPROVE_PLAN="atlas://plans/1234"
+ATLAS_OUTPUT_SCHEMA_PLAN_APPROVE_STATUS=""
 -- schema-plan-approve/1/args --
 schema plan list --format {{ json . }} --context {"scmType":"GITLAB"} --pending --auto-approve
 
diff --git a/atlasaction/testdata/gitlab/schema-plan.txtar b/atlasaction/testdata/gitlab/schema-plan.txtar
index 8d72fad2..fb8fdc81 100644
--- a/atlasaction/testdata/gitlab/schema-plan.txtar
+++ b/atlasaction/testdata/gitlab/schema-plan.txtar
@@ -15,12 +15,12 @@ atlas-action --action=schema/plan
 stdout 'Schema plan does not exist, creating a new one with name "pr-1-3RRRcLHF"'
 
 cmp comments-expected/1 comments/1
-output expected-output.env
+output .env.expected-output
 
--- expected-output.env --
-link=http://test.atlasgo.cloud/schemas/141733920769/plans/210453397511
-plan=atlas://app/plans/20241010143904
-status=PENDING
+-- .env.expected-output --
+ATLAS_OUTPUT_SCHEMA_PLAN_LINK="http://test.atlasgo.cloud/schemas/141733920769/plans/210453397511"
+ATLAS_OUTPUT_SCHEMA_PLAN_PLAN="atlas://app/plans/20241010143904"
+ATLAS_OUTPUT_SCHEMA_PLAN_STATUS="PENDING"
 -- schema-plan/1/args --
 schema plan list --format {{ json . }} --context {"repo":"my-project","branch":"test-branch","commit":"123","url":"https://gitlab.com/projects/my-project/merge_requests/1","username":"user","userID":"123","scmType":"GITLAB"} --pending --auto-approve