1 Introduction
2 Interface
3 Scanner
4 Parser
5 Analyser
6 Tangle
7 Weave
8 Shell
9 Commands
10 Glossary
11 References

FunnelWeb Reference Manual

9.9 Eneo

The eneo command takes one filename argument. If the file does not exist, no action is taken. If the file does exist, it is deleted. In both cases success status is returned. However, if the file exists and cannot be deleted, eneo returns severe status.

Syntax  : eneo = "eneo" s filename
Examples: eneo result.out

The eneo command was added so as to allow regression testing scripts to ensure that existing output files were not present before proceeding with a test run. If FunnelWeb were to fail to generate an output file, it would be extremely undesirable for the old version to be used.

ENEO stands for Establish the Non Existence Of. Most operating systems provide a command to delete files. Typically these commands are verbs such as "delete", "remove", and "kill". As a consequence, the designers of delete commands usually consider the command to have failed if it fails to find the file to be deleted. However, in scripts, the delete command is very commonly used to establish the non-existence of  one or more files. Typically, a script is starting up and needs to clear the air before getting started. If the files are there, they should be deleted; if they are not, then that's OK too. (Note: As far as I know, the eneo command is original).

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