tail does not work with '+' short option

[Paolo Melacarne]

Binary package hint: coreutils

Version: coreutils 6.10-3ubuntu2 (hardy)

Self explanatory transcript follows.

shell prompt> tail +50 fname1 > fname2
tail: cannot open `+50' for reading: no such file or directory
...
shell prompt> tail --lines=+50 fname1 > fname2

[OK]

[JM Williams (jmdwilliams)]

Confirming (coreutils 6.10-3ubuntu2 also).

However, this is by design, to comply with POSIX, as explained in GNU coreutils FAQ nº 33: Old tail plus N syntax now fails:
http://www.gnu.org/software/coreutils/faq/#Old-tail-plus-N-syntax-now-fails

Whether +N represents a file or a line reference apparently depends on which POSIX version is followed: 1003.2-1992 or 1003.1-2001.

The man page lists only the now-recommended syntaxes: -n, --lines=N. The info documentation, however, explains that, “For compatibility ‘tail’ also supports an obsolete usage ‘tail -[COUNT][bcl][f] [FILE]….’ The info documentation (and, quoting it, the above FAQ) also explains that the +N notation can be enabled (for tail, “sort, uniq, touch and perhaps other programs”) by exporting the setting _POSIX2_VERSION=199209.

There is a bug report for this in the Debian bug tracker (nº 471264) and a (Closed Invalid) one in the GNU bug tracker (nº 21549).

[JM Williams (jmdwilliams)]

Instead, marking as Invalid rather than Confirmed because “the report describes the software's normal behaviour” (https://help.launchpad.net/BugStatuses).