fix(execute-command): fix $-pattern substitution, maxBuffer vs timeout detection, bestPractices text

apps/sim/app/api/execute-command/run/route.ts

@@ -131,7 +131,7 @@ function resolveTagVariables(
       stringValue = String(result.value)
     }
 
-    resolved = resolved.replace(new RegExp(escapeRegExp(match), 'g'), stringValue)
+    resolved = resolved.replace(new RegExp(escapeRegExp(match), 'g'), () => stringValue)
   }
 
   return resolved
@@ -160,6 +160,7 @@ interface CommandResult {
   stderr: string
   exitCode: number
   timedOut: boolean
+  maxBufferExceeded: boolean
 }
 
 /**
@@ -182,12 +183,14 @@ function executeCommand(
       (error, stdout, stderr) => {
         if (error) {
           const killed = error.killed ?? false
+          const isMaxBuffer = killed && /maxBuffer/.test(error.message ?? '')
           const exitCode = typeof error.code === 'number' ? error.code : 1
           resolve({
             stdout: stdout.trimEnd(),
             stderr: stderr.trimEnd(),
             exitCode,
-            timedOut: killed,
+            timedOut: killed && !isMaxBuffer,
+            maxBufferExceeded: isMaxBuffer,
           })
           return
         }
@@ -196,6 +199,7 @@ function executeCommand(
           stderr: stderr.trimEnd(),
           exitCode: 0,
           timedOut: false,
+          maxBufferExceeded: false,
         })
       }
     )
@@ -206,6 +210,7 @@ function executeCommand(
         stderr: err.message,
         exitCode: 1,
         timedOut: false,
+        maxBufferExceeded: false,
       })
     })
   })
@@ -297,6 +302,18 @@ export async function POST(req: NextRequest) {
       })
     }
 
+    if (result.maxBufferExceeded) {
+      return NextResponse.json({
+        success: false,
+        output: {
+          stdout: result.stdout,
+          stderr: result.stderr,
+          exitCode: result.exitCode,
+        },
+        error: `Command output exceeded maximum buffer size of ${MAX_BUFFER / 1024 / 1024}MB`,
+      })
+    }
+
     return NextResponse.json({
       success: true,
       output: {

apps/sim/blocks/blocks/execute-command.ts

@@ -16,7 +16,7 @@ export const ExecuteCommandBlock: BlockConfig<ExecuteCommandOutput> = {
   - Use <blockName.output> syntax to reference outputs from other blocks.
   - Use {{ENV_VAR}} syntax to reference environment variables.
   - The working directory defaults to the server process directory if not specified.
-  - A non-zero exit code is treated as an error. Use || true to suppress errors if needed.
+  - A non-zero exit code is returned as data (exitCode > 0), not treated as a workflow error. Use a Condition block to branch on exitCode if needed.
   `,
   docsLink: 'https://docs.sim.ai/blocks/execute-command',
   category: 'blocks',