Data Flow Control

Import contains provisions for jumping ahead in a file and then backing up (using rewind).

This has several uses. In particular, it is often useful to search through the header of a file for certain clues as to its identity and then back up again to read in the name of requests or components which were deliberately skipped the first time through.

The find and qfind commands allow you to jump ahead in a file. These commands are identical, except that find supports regular expressions, while qfind searches for a simple string. Currently, only the following special characters are supported:

[  ]  .   *   +   ^   $   ?

String literals (including regular expressions) can be surrounded by either single or double quotes. Whichever type of quote is used, the other type can be used within the parameter string without terminating it.

Both find and qfind position the file pointer at the first character of the file following the string or regular expression that was matched. If either search command does not find its target before either the end of the file is reached or maxfind (a predefined variable) lines have been searched, a failure condition results.