Interpretations

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

IEEE Standards Interpretation for IEEE Std 1003.1™-1990 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)

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Interpretation Request #10
Topic: colon in filenames Relevant Sections: 2.2.2.32, 2.2.2.56, 2.2.2.57, 2.6 Classification: editorial defect

In 2.2.2.32 filename, page 14, lines 179-180:
"The characters composing the name may be selected from the set of all character values excluding the slash character and the null character."

In 2.2.2.57 pathname, page 17, lines 268-269:
"It has an optional beginning slash, followed by zero or more filenames separated by slashes."

In 2.2.2.56 path prefix, page 17, lines 264-265:
"A pathname, with an optional ending slash, that refers to a directory."

In 2.6 Environment Description [PATH], page 28, lines 730-731:
"The prefixes are separated by a colon (:)."

If the PATH environment variable contains a path prefix that includes a filename that includes a colon, shall conforming implementations treat this colon as part of the filename, or as a path prefix separator, or is either behavior acceptable? Are conforming applications prohibited from setting a value of the PATH environment variable that includes a colon as part of a path prefix?

Interpretation Response
Implementations shall interpret all colons in the PATH environment variable as separators. Conforming applications must therefore avoid using colons in pathnames which may be included in the PATH environment variable.

Rationale for Interpretation
The definition of "separated" on page 28 line 731 accords with normal computing practice, which accepts that separator characters cannot be embedded within the separated fields.