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Last update: 1997-05-20
9945-2-120 _____________________________________________________________________________ Topic: expr Relevant Sections: 4.22.7.1 Defect Report: ----------------------- Date: Tue, 2 May 1995 15:17:17 -0700 From: Greg Burrell <[email protected]> Defect Report: ----------------------- I would like to request an official, binding interpretation from WG15 concerning the following point in ISO/IEC 9945-2:1993 (POSIX.2). Subclause 4.22.7.1 of POSIX.2 specifies the syntax and semantics of the expr utility. This section reads: The ':' matching operator shall compare the string resulting from the evaluation of expr1 with the BRE pattern resulting from the evaluation of expr2. BRE syntax shall be that defined in 2.8.3, except that all patterns are "anchored" to the beginning of the string (that is, only sequences starting at the first character of a string shall be matched by the BRE). Therefore, it is unspecified whether ^ is a special character in that context. Note that this description does not say that it is "implementation defined", but rather "unspecified" whether ^ is an anchor when used in the BRE of an expr matching expression. As such, this implies that a conforming implementation of expr need not even behave consistently from one invocation to the next when a ^ is used in a BRE on the right side of a ':' operator. Since the BRE is not a subexpression, the system defined behavior of anchors in subexpressions does not apply here. Is this the intention? Thank you for your attention to this matter. Sincerely, Greg Burrell Mindcraft, Inc. [email protected] +1 415 323-9000 x125 Interpretation response ------------------------ It is difficult to state what the intention was, but the standard is clear. If "implementation defined" were used instead of "unspecified", it would not affect a conforming POSIX.2 application. Rationale ------------- None. Forwarded to Interpretations group: May 04 1995 Proposed resolution forwarded: Aug 11 1995 Finalized: Sept 12 1995