diff --git a/Tasks/BashV3/Tests/L0.ts b/Tasks/BashV3/Tests/L0.ts
index 9d3a2aa7865c..0c1f3828935b 100644
--- a/Tasks/BashV3/Tests/L0.ts
+++ b/Tasks/BashV3/Tests/L0.ts
@@ -20,6 +20,7 @@ describe('Bash Suite', function () {
     it('Runs an inline script correctly', (done: MochaDone) => {
         this.timeout(5000);
 
+        delete process.env['AZP_BASHV3_OLD_SOURCE_BEHAVIOR'];
         let tp: string = path.join(__dirname, 'L0Inline.js');
         let tr: ttm.MockTestRunner = new ttm.MockTestRunner(tp);
 
@@ -35,6 +36,30 @@ describe('Bash Suite', function () {
     it('Runs a checked in script correctly', (done: MochaDone) => {
         this.timeout(5000);
 
+        delete process.env['AZP_BASHV3_OLD_SOURCE_BEHAVIOR'];
+        let tp: string = path.join(__dirname, 'L0External.js');
+        let tr: ttm.MockTestRunner = new ttm.MockTestRunner(tp);
+
+        tr.run();
+
+        runValidations(() => {
+            assert(tr.succeeded, 'Bash should have succeeded.');
+            assert(tr.stderr.length === 0, 'Bash should not have written to stderr');
+            if (process.platform === 'win32') {
+                // This is different on windows because we change the script name to make sure the normalization call is happening.
+                assert(tr.stdout.indexOf(`Writing bash 'temp/path/script' to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
+            } else {
+                assert(tr.stdout.indexOf(`Writing bash 'path/to/script' to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
+            }
+            
+            assert(tr.stdout.indexOf('my script output') > 0,'Bash should have correctly run the script');
+        }, tr, done);
+    });
+
+    it('Runs a checked in script correctly when using the old behavior', (done: MochaDone) => {
+        this.timeout(5000);
+
+        process.env['AZP_BASHV3_OLD_SOURCE_BEHAVIOR'] = "true";
         let tp: string = path.join(__dirname, 'L0External.js');
         let tr: ttm.MockTestRunner = new ttm.MockTestRunner(tp);
 
@@ -57,6 +82,7 @@ describe('Bash Suite', function () {
     it('Adds arguments to the script', (done: MochaDone) => {
         this.timeout(5000);
 
+        delete process.env['AZP_BASHV3_OLD_SOURCE_BEHAVIOR'];
         let tp: string = path.join(__dirname, 'L0Args.js');
         let tr: ttm.MockTestRunner = new ttm.MockTestRunner(tp);
 
@@ -67,9 +93,9 @@ describe('Bash Suite', function () {
             assert(tr.stderr.length === 0, 'Bash should not have written to stderr');
             if (process.platform === 'win32') {
                 // This is different on windows because we change the script name to make sure the normalization call is happening.
-                assert(tr.stdout.indexOf(`Writing . 'temp/path/script' myCustomArg to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
+                assert(tr.stdout.indexOf(`Writing bash 'temp/path/script' myCustomArg to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
             } else {
-                assert(tr.stdout.indexOf(`Writing . 'path/to/script' myCustomArg to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
+                assert(tr.stdout.indexOf(`Writing bash 'path/to/script' myCustomArg to temp/path/fileName.sh`) > 0, 'Bash should have written the script to a file');
             }
             
             assert(tr.stdout.indexOf('my script output') > 0,'Bash should have correctly run the script');
diff --git a/Tasks/BashV3/Tests/L0Args.ts b/Tasks/BashV3/Tests/L0Args.ts
index ddc13527eb0e..c9bcd46089b3 100644
--- a/Tasks/BashV3/Tests/L0Args.ts
+++ b/Tasks/BashV3/Tests/L0Args.ts
@@ -51,7 +51,8 @@ let a: ma.TaskLibAnswers = <ma.TaskLibAnswers>{
         'path/to/script': {
             isFile() {
                 return true;
-            }
+            },
+            mode: '777'
         }
     }
 };
diff --git a/Tasks/BashV3/Tests/L0External.ts b/Tasks/BashV3/Tests/L0External.ts
index 09eb1128354c..78f6a469ad2e 100644
--- a/Tasks/BashV3/Tests/L0External.ts
+++ b/Tasks/BashV3/Tests/L0External.ts
@@ -50,7 +50,8 @@ let a: ma.TaskLibAnswers = <ma.TaskLibAnswers>{
         'path/to/script': {
             isFile() {
                 return true;
-            }
+            },
+            mode: '777'
         }
     }
 };
diff --git a/Tasks/BashV3/bash.ts b/Tasks/BashV3/bash.ts
index 9a4b091c77bf..96a62847409b 100644
--- a/Tasks/BashV3/bash.ts
+++ b/Tasks/BashV3/bash.ts
@@ -1,6 +1,5 @@
 import fs = require('fs');
 import path = require('path');
-import os = require('os');
 import tl = require('azure-pipelines-task-lib/task');
 import tr = require('azure-pipelines-task-lib/toolrunner');
 var uuidV4 = require('uuid/v4');
@@ -45,8 +44,10 @@ async function run() {
         let input_filePath: string;
         let input_arguments: string;
         let input_script: string;
+        let old_source_behavior: boolean;
         let input_targetType: string = tl.getInput('targetType') || '';
         if (input_targetType.toUpperCase() == 'FILEPATH') {
+            old_source_behavior = !!process.env['AZP_BASHV3_OLD_SOURCE_BEHAVIOR'];
             input_filePath = tl.getPathInput('filePath', /*required*/ true);
             if (!tl.stats(input_filePath).isFile()) {
                 throw new Error(tl.loc('JS_InvalidFilePath', input_filePath));
@@ -72,7 +73,26 @@ async function run() {
                 targetFilePath = input_filePath;
             }
 
-            contents = `. '${targetFilePath.replace("'", "'\\''")}' ${input_arguments}`.trim();
+            // Choose 1 of 3 behaviors:
+            // If they've set old_source_behavior, source the script. This is what we used to do and needs to hang around forever for back compat reasons
+            // If the executable bit is set, execute the script. This is our new desired behavior.
+            // If the executable bit is not set, source the script and warn. The user should either make it executable or pin to the old behavior.
+            // See https://github.com/Microsoft/azure-pipelines-tasks/blob/master/docs/bashnote.md
+            if (old_source_behavior) {
+                contents = `. '${targetFilePath.replace("'", "'\\''")}' ${input_arguments}`.trim();
+            } else {
+                // Check if executable bit is set
+                const stats: fs.Stats = tl.stats(input_filePath);
+                // Check file's executable bit.
+                if ((stats.mode & 1) > 0) {
+                    contents = `bash '${targetFilePath.replace("'", "'\\''")}' ${input_arguments}`.trim();
+                }
+                else {
+                    tl.debug(`File permissions: ${stats.mode}`);
+                    tl.warning('Executable bit is not set on target script, sourcing instead of executing. More info at https://github.com/Microsoft/azure-pipelines-tasks/blob/master/docs/bashnote.md');
+                    contents = `. '${targetFilePath.replace("'", "'\\''")}' ${input_arguments}`.trim();
+                }
+            }
             console.log(tl.loc('JS_FormattedCommand', contents));
         }
         else {
@@ -167,4 +187,4 @@ async function run() {
     }
 }
 
-run();
+run();
\ No newline at end of file
diff --git a/Tasks/BashV3/task.json b/Tasks/BashV3/task.json
index 567e3653dbfc..afd56123f12a 100644
--- a/Tasks/BashV3/task.json
+++ b/Tasks/BashV3/task.json
@@ -18,7 +18,7 @@
     "version": {
         "Major": 3,
         "Minor": 163,
-        "Patch": 0
+        "Patch": 1
     },
     "releaseNotes": "Script task consistency. Added support for multiple lines and added support for Windows.",
     "minimumAgentVersion": "2.115.0",
diff --git a/Tasks/BashV3/task.loc.json b/Tasks/BashV3/task.loc.json
index 82b6d906c8e1..1e9d73a6775f 100644
--- a/Tasks/BashV3/task.loc.json
+++ b/Tasks/BashV3/task.loc.json
@@ -18,7 +18,7 @@
   "version": {
     "Major": 3,
     "Minor": 163,
-    "Patch": 0
+    "Patch": 1
   },
   "releaseNotes": "ms-resource:loc.releaseNotes",
   "minimumAgentVersion": "2.115.0",