Redet Reference Manual: Information
Author: Bill Poser

## Information

Most of the information provided comes in the form of messages displayed in the message region or via the various help functions. A few pieces of information, however, are provided in other ways.

The Redet version is shown in the title bar after its name. The version is followed in turn by the current locale.

Most machines will not have all of the programs supported by Redet installed. When Redet starts up, it checks the availability of all supported programs and disables the Program menu entries of those that it cannot find. Programs whose features have been tested in the current locale are shown in different colors from those that have not.

In this example, the three variants of Php are disabled because Php is not installed on this system. Nawk actually is installed on this system, but in a location that is not on the current search path, so Redet cannot find it. agrep, lua,mysql, and tcl are marked as having been tested.

The name of the currently selected program constitutes the second component of the label of the Execute button. The Execute button also indicates whether the selected program is one in which any line containing a match to the regular expression is considered a match or whether the regular expression must match exactly.

For example, if you give a string of ordinary characters, such as mare, as a regular expression to grep, it will match any line containing mare, e.g. mares and amaretto.

On the other hand, if you supply the same string to Java, it will match only mare, not any of the lines with additional characters before and after.

If any line containing a match is treated as a match, the name of the program is surrounded by stars, reflecting the fact that such a program may be though of as implicitly adding "match anything" expressions at both ends of the regular expression entered by the user. If the program is one that requires an exact match, the program name is preceded by a circumflex ˆ and followed by a dollar sign $, reflecting the fact that such a program may be thought of as implicitly adding "beginning of string" and "end of string" delimiters to the regular expression entered by the user.

The situation need not be symmetric: it is possible for a program to add an implicit "match anything" on one side of the regular expression and not on the other. In fact, at least one program exhibits this behavior. Redet therefore tests for the two sides separately and marks them separately.

Additional information about the current program that does not take the form of a palette feature can be obtained by selecting the This Program entry from the Help menu.

The command Save Command Information on the File menu writes to a file the current regular expression and substitution expression, the command line that would be executed, and the daughter program that would be executed. This is useful for debugging and for users who want to use a language or program directly themselves and would like to see how Redet does it.

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