9.6 Diff

9.6 Diff

The diff command reads in two text files and 

appends

  a report to a log file

containing a list of the differences between the two input files. If the log

Tutorial

file does not already exist, an empty one is created first.

Developer

Syntax  :

   diff = "diff" s filename s filename s

Reference

                   filename s ["ABORT"]

1 Introduction

Examples:

2 Interface

   diff result.tex answer.tex diff.log

   diff $Otest23.out $Atest23.out $Ldiff.log ABORT

3 Scanner

4 Parser

The diff command performs a full line based differences operation. It will

5 Analyser

identify different sections in a file, even if they are of differing length.

6 Tangle

The implementation of the diff command is quite complicated. To be sure

7 Weave

that it is at least getting its same/different proclamation right, the diff

8 Shell

command performs a binary comparison as an extra check.

9 Commands

The following points describe the rules for determining the result status.

10 Glossary

11 References

diff aborts with a severe error if the log file cannot be opened or

1.  

created for appending.

SEARCH

An ordinary error is generated if either or both of the input files

2.  

cannot be opened.

If, at the end of the run, the two input files have not been proven to

3.  

be identical, and the ABORT keyword is present, diff returns severe

status.

diff returns success status if none of the above conditions (or similar

4.  

conditions) occur, even if the two files are different.

The diff command 

appends

  its differences report rather than merely

writing it. This allows a regression test script to perform a series of

regression tests and produce a report for the user.

The diff command was added to the shell after it had become apparent that

the simpler compare command was not yielding enough information.

Whereas early on, regression testing was treated mainly as a tool to ensure

that FunnelWeb was being ported to other machines correctly, it began to

place an increasing role during development in identifying the effects of

changes made to the code. The diff command supports this application of

regression testing by pinpointing the differences between nearly identical

text files.

http://www.ross.net/funnelweb/reference/commands_diff.html (1 of 2) [3/3/2000 10:44:36 PM]