# Expect

> extension to the Tcl scripting language

**Wikidata**: [Q2642029](https://www.wikidata.org/wiki/Q2642029)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Expect)  
**Source**: https://4ort.xyz/entity/expect

## Summary
Expect is an extension to the Tcl scripting language that automates interactive applications such as telnet, ftp, passwd, and hundreds of others. It was created by Don Libes, an American computer scientist, to allow scripts to interact with programs that expect human input.

## Key Facts
- Created by Don Libes, an American computer scientist born in 1958
- Latest stable version is 5.45.4, released on February 4, 2018
- Available under public domain license
- Runs on Microsoft Windows and other operating systems
- Listed as both a programming language and command line interface language
- Has 10 Wikipedia sitelinks across multiple languages
- Available in major package repositories including Debian, FreeBSD, OpenBSD, and Arch Linux

## FAQs
### Q: What is Expect used for?
A: Expect is used to automate interactive applications that normally require human interaction, such as telnet sessions, ftp transfers, and password changes. It allows scripts to interact with programs that expect human input.

### Q: Who created Expect?
A: Expect was created by Don Libes, an American computer scientist born in 1958, who developed it as an extension to the Tcl scripting language.

### Q: What programming language is Expect based on?
A: Expect is an extension to the Tcl scripting language, meaning it builds upon and extends Tcl's capabilities to handle interactive applications.

## Why It Matters
Expect revolutionized the automation of interactive applications by providing a way to script interactions that previously required manual human input. Before Expect, automating tasks like remote logins, file transfers, or system administration procedures that required interactive prompts was extremely difficult or impossible. By extending Tcl with the ability to "expect" certain outputs and respond accordingly, Don Libes created a tool that dramatically improved system administration efficiency and enabled complex automation workflows. This capability is particularly valuable in network administration, automated testing, and any scenario where repetitive interactive tasks need to be performed reliably and consistently.

## Notable For
- First major tool to automate interactive applications through scripting
- Public domain licensing made it freely available for widespread adoption
- Cross-platform compatibility including Microsoft Windows support
- Integration with Tcl, a widely-used scripting language
- Long-term maintenance with stable releases over multiple decades

## Body
### Development and History
Expect was developed by Don Libes at the National Institute of Standards and Technology (NIST) as an extension to Tcl. The tool was designed to address the challenge of automating interactive applications that typically require human intervention, such as those using telnet, ftp, or passwd commands.

### Technical Architecture
Expect operates by spawning child processes and then monitoring their output for specific patterns. When a pattern is matched, Expect can send predetermined responses, effectively simulating human interaction. This pattern-matching capability is what gives Expect its name - it "expects" certain outputs and responds accordingly.

### Versions and Releases
The software has seen multiple stable releases, with version 5.45.4 being the current stable release as of February 4, 2018. Earlier versions include 5.44.1.15 from March 11, 2010. The project maintains active development and distribution through various channels.

### Platform Support
Expect runs on multiple operating systems, with specific support for Microsoft Windows noted in the source material. It's available through major package management systems including Debian's stable repository, FreeBSD ports, OpenBSD ports, Arch Linux packages, and MacPorts.

### Licensing and Distribution
Expect is released under public domain licensing, making it freely available for any use without restrictions. This licensing approach has contributed to its widespread adoption and integration into various operating system distributions and package repositories.

### Integration and Ecosystem
As an extension to Tcl, Expect leverages the existing Tcl ecosystem while adding specialized capabilities for interactive application automation. It's included in major software repositories and package managers, ensuring broad accessibility across different computing environments.

## References

1. [2010](https://sourceforge.net/projects/expect/files/Expect/5.44.1.15/)
2. [Expect: Expect](https://core.tcl-lang.org/expect/index)
3. [Expect -  Browse /Expect/5.45.4 at SourceForge.net. 2018](https://sourceforge.net/projects/expect/files/Expect/5.45.4/)
4. Freebase Data Dumps. 2013
5. [PHP: expect:// - Manual](https://secure.php.net/manual/en/wrappers.expect.php)