---
name: "h2o"
section: "8"
platform: "linux"
package: "h2o"
version: "2.2.5+dfsg2-7"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/h2o"
---

# h2o(8)

optimized HTTP/1.x, HTTP/2 server

## NAME

h2o - optimized HTTP/1.x, HTTP/2 server

## SYNOPSIS

**h2o** \[*options*\]

## DESCRIPTION

H2O is a performance-optimized HTTP/1.x and HTTP/2 web server. Designed from ground-up, the server takes full advantage of HTTP/2 features including prioritized content serving and server push.

This manual page describes the options supported by the **h2o** command. Note that H2O should in most cases be run as a system service (through a [**systemd**(1)](/systemd/1.md) service or an initscript).

## OPTIONS

- **-c**, **--conf** FILE

  Configuration file (default: */etc/h2o/h2o.conf*)

- **-m**, **--mode** *mode*

  *mode* specifies one of the following modes:

  - **worker**

    the **h2o** process will stay in the foreground and handle all incoming connections itself (default).

  - **master**

    **h2o** will be started using the **/usr/share/h2o/start\_server** helper; in this mode the **start\_server** process will stay in the foreground and spawn an **h2o** worker process for handling incoming connections. **SIGHUP** can be sent to the master process to reconfigure or upgrade the server without service downtime.

  - **daemon**

    spawns a **master** process in the background and exits. **error-log** must be configured when using this mode, as all errors are logged to the error log instead of output to standard error.

  - **test**

    tests the configuration and exits

- **-t**, **--test**

  Synonym of \`--mode=test\`

- **-v**, **--version**

  Prints the version number

- **-h**, **--help**

  Prints usage help.

## SEE ALSO

The full documentation for **h2o** is available in the **h2o-doc** package, under */usr/share/doc/h2o*.

## AUTHOR

H2O was written by DeNa Co., Ltd. and Kazuho Oku and distributed under the MIT license.

This manpage was written by Apollon Oikonomopoulos \<apoikos@debian.org\> for the Debian project, but may be used by others.