Interpretations

Answering questions that may arise related to the meaning of portions of an IEEE standard concerning specific applications.

IEEE Standards Interpretations for IEEE Std 1003.2™-1992 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)--Part 2: Shell and Utilities

Copyright © 1996 by the Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue New York, New York 10016-5997 USA All Rights Reserved.

These are interpretations of IEEE Std 1003.2-1992. Interpretations are issued to explain and clarify the intent of a standard and do not constitute an alteration to the original standard. In addition, interpretations are not intended to supply consulting information. Permission is hereby granted to download and print one copy of this document. Individuals seeking permission to reproduce and/or distribute this document in its entirety or portions of this document must contact the IEEE Standards Department for the appropriate license. Use of the information contained in this document is at your own risk.

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Interpretation Request #130
Topic: awk - escape sequences in ERE constants Relevant Clauses: 4.1.7.8 (6)

I'd like an interpretation of how awk should be evaluating the following ERE constant: /x[ab\135cd]y/ # note that \135 is the octal escape # sequence for the ']' character. Should this be interpreted as /x[ab]cd]y/ # this matches the string "xacd]y" or should this be interpreted as (is done historically) /x[]y/ # this matches "x]y" My reading of subsection (6) lines 1113-1116 indicates that the former interpretation is correct but this does not conform to historical practice.

Interpretation Response
The standard clearly states the behavior for ERE's in awk, and conforming implementations must conform to this, even if it does not match some historic practices. However, concerns have been raised about this which are being forwarded to the sponsor.

Rationale for Interpretation
None.