MSID Highlights MSID Opportunities MSID Partners MSID Products MEL MSID Programs MSID Conferences MSID Search MSID Staff MSID Services MSID Standards MSID Publications NIST MSID MSID MSID
Publications

PLEASE NOTE: The Publications System provided by the Manufacturing Systems Integration Division (MSID) has moved to: http://www.mel.nist.gov/msidlibrary/publications.html. The pages below are maintained for archival purposes only.

Publication summary

Author(s): Don Libes

Publication date: November 1991

Citation: Don Libes: "expect; Scripts for Controlling Interactive Processes," Computing Systems Magazine, Vol. 4, No. 2, University of California Press, Berkeley, CA, November, 1991.

Key words: expect, interaction, POSIX, programmed dialogue, shell, Tcl, UNIX

Availability:

  • Postscript
  • A paper copy of this document is available by contacting Kristy Thompson [web,email]
Abstract:
Contemporary shells provide only minimal control (starting, stopping, etc.) over programs, leaving interaction up to users. This means that you cannot run some program non- interactively, such as "passwd". Some programs can be run non-interactively, but only with a loss of flexibility, such as "fsck". This is where the tool-building philosophy of UNIX begins to break down. "expect" crosses this line, solving a number of long-standing problems in the UNIX environment.

"expect" uses Tcl as a language core. In addition, "expect" can use any UNIX program, whether or not it is interactive. The result is a classic example of a little language synergistically generating large power when combined with the rest of the UNIX workbench.

Previous papers have described the implementation of "expect" and compared it to other tools. This paper concentrates on the language, primarily by presenting a variety of scripts. Several scripts demonstrate brand-new features of "expect".

Attention users of these documents: The information contained in these files should not be altered in any way. Attempts to change these files will adversely impact the integrity of the information and its usefulness. It is intended for use as is and will lose its usefulness if changed.

 

Send questions or comments to Webmaster.