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™-2001 IEEE Standard Standard for Information Technology -- Portable Operating System Interface (POSIX®)

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Interpretation Request #101
Topic: ls -l output Relevant Sections: XCU ls

In the typical case where a file has no alternate or additional access control method, POSIX currently requires a ‹space› followed by at least one ‹blank› between the graphic characters of the first and second columns of an "ls -l" output line.

This appears to be an unintended consequence of POSIX, as common and longstanding practice is to output only a single space. Here is an example, taken from Solaris 10, listing a file with a link count equal to 100:

$ ls -l f
-rw-r--r-- 100 eggert faculty 0 May 15 22:31 f

Only a single space separates the first and second columns of output. (The output is the same regardless of whether /bin/ls or /usr/xpg4/bin/ls is used.) However, POSIX currently requires that a ‹space› must follow the "-", and that one or more ‹blank›s must then separate the ‹space› from the "100".

Action:

Change XCU page 574 line 22176 from:

"%c%s%s%s%c", ‹entry type›, ‹owner permissions›,

to:

"%c%s%s%s%s", ‹entry type›, ‹owner permissions›,

Change XCU page 574 lines 22179-22181 from:

The ‹optional alternate access method flag› shall be a single ‹space› if there is no alternate or additional access control method associated with the file; otherwise a printable character shall be used.

to:

The ‹optional alternate access method flag› shall be the empty string if there is no alternate or additional access control method associated with the file; otherwise it shall be a string containing a single printable character that is not a ‹blank›.

Interpretation Response
The standards states the requirements, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor.

Rationale for Interpretation
None.