---
name: "cat"
section: "3tcl"
platform: "linux"
package: "tcllib"
version: "2.0+dfsg-4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/cat/3tcl"
---

# cat(3tcl)

Concatenation channel

```

```

## NAME

tcl::chan::cat - Concatenation channel

## SYNOPSIS

package require **Tcl 8.5 9**

package require **TclOO**

package require **tcl::chan::core ?1.1?**

package require **tcl::chan::cat ?1.0.4?**

**::tcl::chan::cat** *chan*...

```

```

## DESCRIPTION

The **tcl::chan::cat** package provides a command creating concatenation channels. These are non-seekable channels owning a list of subordinate channels whose contents they return in order, until all are exhausted. In this manner the channel is the concatentation of the contents of all the sub-ordinate channels.

Note that the created channels take ownership of the channels they were constructed with. Whenever they have exhausted one of their channel it will be closed. Similarly, closing the cat channel will close all the sub-ordinates it still has.

The internal **TclOO** class implementing the channel handler is a sub-class of the **tcl::chan::core** framework.

Event handling is delegated to the currently active sub-channel.

## API

- **::tcl::chan::cat** *chan*...

  This command creates the concatenation channel using all the provided channels, and returns its handle.

## BUGS, IDEAS, FEEDBACK

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category *virtchannel* of the *Tcllib Trackers* \[http://core.tcl.tk/tcllib/reportlist\]. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide *unified diffs*, i.e the output of **diff -u**.

Note further that *attachments* are strongly preferred over inlined patches. Attachments can be made by going to the **Edit** form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## KEYWORDS

concatenation channel, reflected channel, tip 219, virtual channel

## CATEGORY

Channels

## COPYRIGHT

```
Copyright (c) 2011 Andreas Kupries <andreas_kupries@users.sourceforge.net>
```