IEEE Standards Interpretations for IEEE Std 1003.2™-1992 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)--Part 2: Shell and Utilities
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Interpretation Request #130
Topic: awk - escape sequences in ERE constants Relevant Clauses: 18.104.22.168 (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) /xy/ # 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.
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