{"record":{"id":"dd7e1f4a5769aa94","repo":"firecrawl/open-lovable","slug":"failed-to-write-file-via-command-writeresult-st","errorCode":null,"errorMessage":"Failed to write file via command: ${writeResult.stderr}","messagePattern":"Failed to write file via command: (.+?)","errorType":"exception","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"lib/sandbox/providers/vercel-provider.ts","lineNumber":186,"sourceCode":"      // Write file using echo and redirection\n      const escapedContent = content\n        .replace(/\\\\/g, '\\\\\\\\')\n        .replace(/\"/g, '\\\\\"')\n        .replace(/\\$/g, '\\\\$')\n        .replace(/`/g, '\\\\`')\n        .replace(/\\n/g, '\\\\n');\n      \n      const writeResult = await this.sandbox.runCommand({\n        cmd: 'sh',\n        args: ['-c', `echo \"${escapedContent}\" > \"${fullPath}\"`]\n      });\n      \n      // File written\n      \n      if (writeResult.exitCode === 0) {\n        this.existingFiles.add(path);\n      } else {\n        throw new Error(`Failed to write file via command: ${writeResult.stderr}`);\n      }\n    }\n  }\n\n  async readFile(path: string): Promise<string> {\n    if (!this.sandbox) {\n      throw new Error('No active sandbox');\n    }\n\n    // Vercel sandbox default working directory is /vercel/sandbox\n    const fullPath = path.startsWith('/') ? path : `/vercel/sandbox/${path}`;\n    \n    const result = await this.sandbox.runCommand({\n      cmd: 'cat',\n      args: [fullPath]\n    });\n    \n    // Handle stdout and stderr - they might be functions in Vercel SDK","sourceCodeStart":168,"sourceCodeEnd":204,"githubUrl":"https://github.com/firecrawl/open-lovable/blob/69bd93bae7a9c97ef989eb70aabe6797fb3dac89/lib/sandbox/providers/vercel-provider.ts#L168-L204","documentation":"VercelProvider.writeFile falls back to writing via a shell command (e.g. heredoc/echo) inside the sandbox; when that command exits non-zero, the provider throws 'Failed to write file via command: <stderr>'. Unlike the null-sandbox guard, the sandbox exists but the write itself failed.","triggerScenarios":"The fallback command's exitCode !== 0 — typically shell quoting/escaping problems when content contains backticks, $, quotes, or newlines; path not writable in /vercel/sandbox; disk-full or command not available in the sandbox image.","commonSituations":"Writing generated code/TSX with template literals or dollar signs that the shell interpolates; very large files blowing argument/heredoc limits; read-only working directory; sandbox image lacking the shell utility used by the fallback.","solutions":["Read writeResult.stderr in the thrown message and fix the specific shell/quoting issue; prefer base64-encoding content before embedding it in the command and decoding in the sandbox","Use the provider's primary filesystem write API (files.write) and ensure createSandbox() ran so the fallback path is never taken","Sanitize/escape path and content before interpolation","Verify the target directory exists (mkdir -p) and is writable inside the sandbox"],"exampleFix":"// before (fragile interpolation)\nconst cmd = `cat > ${fullPath} <<EOF\\n${content}\\nEOF`;\nawait provider.runCommand(cmd);\n// after (encode to survive shell)\nconst b64 = Buffer.from(content).toString('base64');\nawait provider.runCommand(`mkdir -p $(dirname ${fullPath}) && echo ${b64} | base64 -d > ${fullPath}`);","handlingStrategy":"try-catch","validationCode":"// prefer the native write path and validate inputs first\nif (!provider.sandbox) await provider.createSandbox();\nif (/[`$\"\\\\]/.test(content)) {\n  // shell-sensitive content: use base64-encoded command, not raw heredoc\n}\nif (!content.endsWith('\\n')) content += '\\n';","typeGuard":null,"tryCatchPattern":"try {\n  await provider.writeFile(path, content);\n} catch (e) {\n  if (e instanceof Error && e.message.startsWith('Failed to write file via command:')) {\n    const b64 = Buffer.from(content).toString('base64');\n    await provider.runCommand(`mkdir -p $(dirname ${fullPath}) && echo ${b64} | base64 -d > ${fullPath}`);\n  } else throw e;\n}","preventionTips":["Base64-encode file content before embedding it in shell commands","Escape or avoid shell metacharacters ($, backticks, quotes) in generated files","Ensure target directories exist (mkdir -p) and are writable","Prefer the sandbox's native files.write API over command-based fallbacks","Inspect the stderr embedded in the error message to pinpoint the shell failure"],"tags":["sandbox","vercel","filesystem","shell-escape"],"backgroundTag":"file-write-failed","analyzedSha":"69bd93bae7a9c97ef989eb70aabe6797fb3dac89","analyzedAt":"2026-08-28T22:20:32.339Z","schemaVersion":2},"datasetVersion":"2026-08-29T02:17:18.158Z"}