---
name: "watch"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/watch/8"
---

# watch(8)

snoop on another tty line

## NAME

**watch** – snoop on another tty line

## SYNOPSIS

**watch** \[**-cinotW**\] \[**-f** *snpdev*\] \[*tty*\]

## DESCRIPTION

The **watch** utility allows the user to examine all data coming through a specified tty using the [snp(4)](/snp/4.md) device. If the [snp(4)](/snp/4.md) device is not available, **watch** will attempt to load the module (**snp**). The **watch** utility writes to standard output.

The options are as follows:

- **-c**

  Reconnect on close. If the tty observed by **watch** is closed, automatically reattach to the same tty. If this option is not specified, **watch** will request a new tty if running in interactive mode or exit if running without a controlling tty.

- **-f** *snpdev*

  If this option is specified, **watch** will use *snpdev* as the [snp(4)](/snp/4.md) device. Without this option, **watch** will attempt to find the next available [snp(4)](/snp/4.md) device.

- **-i**

  Force interactive mode. Interactive mode is a default if **watch** is started from a tty. If output is redirected to a file, interactive mode can still be requested by specifying this option.

- **-n**

  Disable the ability to switch the watched tty interactively. This disables both change requests made with \<control-X\> as well as automatic prompting when the current tty is closed or overflows. In all cases where a prompt would be displayed, **watch** will exit. The reconnect flags are unaffected by this option. When this flag is used, \<control-X\> is passed through to the terminal.

- **-o**

  Reconnect on overflow. The behavior of **watch** if the observed tty overflows is similar to the behavior if the observed tty is closed. For more info see [snp(4)](/snp/4.md).

- **-t**

  Print the date and time when observation of a given tty is started.

- **-W**

  Allow write access to observed tty.

- *tty*

  Tty may be specified as a tty-style device, such as a pseudo tty device, a virtual console, or a serial line, etc. Names may be preceded by */dev/*.

## OPERATION

While running in interactive mode, all user input is discarded except for:

- **\<control-G\>**

  Exit **watch**.

- **\<control-W\>**

  Clear screen.

- **\<control-X\>**

  Change attached tty, unless this feature is disabled, in which case control-X is passed to the terminal as with other control characters.

## SEE ALSO

[pty(4)](/pty/4.md), [snp(4)](/snp/4.md), [kldload(8)](/kldload/8.md)

## HISTORY

The **watch** utility first appeared in FreeBSD 2.1.

## AUTHORS

Ugen J.S. Antsilevich ⟨*ugen@NetVision.net.il*⟩

## BUGS

No terminal emulation is performed. All user output is reproduced as-is.