> ## Documentation Index
> Fetch the complete documentation index at: https://tbd-6fc993ce-hypeship-process-execution-guide.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# Process Execution
> Run commands and manage processes alongside the browser
every KERNEL browser runs in a full linux environment. playwright controls what happens in the page; process execution lets you run commands, scripts, and binaries alongside the browser.
use process execution when your browser automation needs software or system access outside a playwright callback. code running alongside the browser can access the same files and local browser services, so you can process downloads without transferring them to your application first, run existing command-line tools, or keep a high-frequency agent loop close to the browser.
use `process.exec` for bounded commands where you need the result before continuing. use `process.spawn` for agents, servers, watchers, interactive shells, and other long-running processes. after spawning a process, you can inspect its status, stream its output, send input, resize its pty, or terminate it.
if your task only needs the `page`, `context`, and `browser` objects, use [playwright execution](/browsers/playwright-execution). use process execution when you need an executable, operating-system tools, a long-running process, or direct filesystem access. for workloads that need their own deployment and invocation lifecycle, use [KERNEL apps](/apps).
## common production patterns
* **co-locate an agent with its browser.** browser agents often make many small tool calls. upload an agent binary with [file i/o](/browsers/file-io), run it alongside chromium, and point it at the local playwright endpoint to remove a round trip through KERNEL's public api from each call. see the [fx co-located agent cookbook](https://github.com/kernel/cookbooks/tree/main/integrations/fx-colocated-agent) for an end-to-end example.
* **process downloads before retrieving them.** unpack archives, extract text from documents, resize images, or compress a directory while the files are still alongside the browser, then retrieve only the final artifacts with file i/o.
* **run existing command-line tools.** upload a pinned binary or script and call it from the same workflow instead of rewriting it as browser automation code.
* **start a session-local helper.** run a local server, callback handler, or file watcher for as long as the browser task needs it.
* **inspect failed browser tasks.** run tools such as `curl`, `ps`, and `ls` to inspect network responses, running processes, logs, and downloaded files before the browser is deleted.
## Run a command synchronously
`process.exec` runs a command and blocks until it exits or times out. `stdout_b64` and `stderr_b64` are base64-encoded, and `exit_code` tells you whether it succeeded.
```typescript Typescript/Javascript theme={null}
import Kernel from '@onkernel/sdk';
const kernel = new Kernel();
const browser = await kernel.browsers.create({});
const result = await kernel.browsers.process.exec(browser.session_id, {
command: 'ls',
args: ['-la', '/tmp'],
});
console.log(Buffer.from(result.stdout_b64 ?? '', 'base64').toString());
console.log('exit code', result.exit_code);
```
```python Python theme={null}
import base64
from kernel import Kernel
kernel = Kernel()
browser = kernel.browsers.create()
result = kernel.browsers.process.exec(
browser.session_id,
command="ls",
args=["-la", "/tmp"],
)
print(base64.b64decode(result.stdout_b64 or "").decode())
print("exit code", result.exit_code)
```
Use `cwd` to set a working directory, `env` to pass environment variables, `as_user`/`as_root` to control privileges, and `timeout_sec` to cap execution time.
## Run a command in the background
`process.spawn` starts a command without waiting for it to finish, returning a `process_id` you use to manage it afterward. This is the right call for long-running processes — a server, a watcher script, an interactive shell.
If your long-running process is a server, pick a port yourself and don't assume it's free — the VM's own infrastructure (live view, CDP, the playwright daemon) already listens on several, including `8080`, `9222`–`9225`, `8888`, `10001`, and `10002`.
```typescript Typescript/Javascript theme={null}
const spawned = await kernel.browsers.process.spawn(browser.session_id, {
command: 'sh',
args: ['-c', 'while true; do echo "tick $(date +%s)"; sleep 5; done'],
});
console.log('process_id', spawned.process_id);
```
```python Python theme={null}
spawned = kernel.browsers.process.spawn(
browser.session_id,
command="sh",
args=["-c", 'while true; do echo "tick $(date +%s)"; sleep 5; done'],
)
print("process_id", spawned.process_id)
```
Pass `allocate_tty: true` to attach a pseudo-terminal for interactive shells, with `cols`/`rows` to set its initial size.
## Manage a running process
### Check status
Poll for whether a spawned process is still running, and its resource usage:
```typescript Typescript/Javascript theme={null}
const status = await kernel.browsers.process.status(spawned.process_id, {
id_or_name: browser.session_id,
});
console.log(status.state, status.exit_code);
```
```python Python theme={null}
status = kernel.browsers.process.status(
spawned.process_id,
id_or_name=browser.session_id,
)
print(status.state, status.exit_code)
```
### Stream stdout and stderr
Read output from a spawned process as it happens over server-sent events:
```typescript Typescript/Javascript theme={null}
const stream = await kernel.browsers.process.stdoutStream(spawned.process_id, {
id_or_name: browser.session_id,
});
for await (const chunk of stream) {
if (chunk.event === 'exit') {
console.log('exited with', chunk.exit_code);
break;
}
console.log(chunk.stream, Buffer.from(chunk.data_b64 ?? '', 'base64').toString());
}
```
```python Python theme={null}
import base64
with kernel.browsers.process.stdout_stream(
spawned.process_id, id_or_name=browser.session_id
) as stream:
for chunk in stream:
if chunk.event == "exit":
print("exited with", chunk.exit_code)
break
print(chunk.stream, base64.b64decode(chunk.data_b64 or "").decode())
```
### Write to stdin
Send base64-encoded input to a running process, e.g. to answer an interactive prompt:
```typescript Typescript/Javascript theme={null}
await kernel.browsers.process.stdin(spawned.process_id, {
id_or_name: browser.session_id,
data_b64: Buffer.from('y\n').toString('base64'),
});
```
```python Python theme={null}
import base64
kernel.browsers.process.stdin(
spawned.process_id,
id_or_name=browser.session_id,
data_b64=base64.b64encode(b"y\n").decode(),
)
```
### Resize a PTY
Resizing only works on a process spawned with `allocate_tty: true` — calling it on a plain process returns a 400. Match the terminal to a live view or client window:
```typescript Typescript/Javascript theme={null}
const shell = await kernel.browsers.process.spawn(browser.session_id, {
command: 'sh',
allocate_tty: true,
cols: 80,
rows: 24,
});
await kernel.browsers.process.resize(shell.process_id, {
id_or_name: browser.session_id,
cols: 120,
rows: 40,
});
```
```python Python theme={null}
shell = kernel.browsers.process.spawn(
browser.session_id,
command="sh",
allocate_tty=True,
cols=80,
rows=24,
)
kernel.browsers.process.resize(
shell.process_id,
id_or_name=browser.session_id,
cols=120,
rows=40,
)
```
### Kill a process
```typescript Typescript/Javascript theme={null}
await kernel.browsers.process.kill(spawned.process_id, {
id_or_name: browser.session_id,
signal: 'TERM',
});
```
```python Python theme={null}
kernel.browsers.process.kill(
spawned.process_id,
id_or_name=browser.session_id,
signal="TERM",
)
```
`signal` accepts `TERM`, `KILL`, `INT`, or `HUP`.
## Root and per-user execution
Pass `as_root: true` or `as_user: ""` on `exec` or `spawn` to control which user the command runs as. This is safe because a Kernel browser is a [unikernel VM](/security#2-4-security-features) with no shared host kernel — root inside your session has no path to other customers or platform infrastructure.
## Via CLI
The [CLI](/reference/cli/browsers#process-control) exposes the same operations:
```bash theme={null}
# Synchronous
kernel browsers process exec --command ls --args -la
# Background, then inspect
kernel browsers process spawn --command python3 --args -m --args http.server
kernel browsers process status
kernel browsers process kill
```
## Related
Upload and download files from a browser VM
Open an interactive SSH session for debugging
All `kernel browsers process` subcommands and flags