On Wednesday 12 April 2006 8:47 pm, Stepan Kasal wrote: > On Wed, Apr 12, 2006 at 08:45:04PM +0200, Ralf Wildenhues wrote: > > here's a patch that I think does more or less what Bruno's patch > > intends to do, against current CVS. > > I worked on the same issue. We both use the same pattern > `sed -n '/@datadir@/p;/@docdir@/p;/@infodir@/p...' ...`
I'd like, if I may, to sound a note of caution concerning this sed command syntax: the use of semicolons as command separators in the sed script is an implementation dependent extension, which is not portable. On some platforms, the test using this sed syntax *will* fail, not because the feature you are testing is unsupported, but because the test itself is invalid. In November 2005, Robert Goulding posted these bug reports on groff@gnu.org: http://lists.gnu.org/archive/html/groff/2005-11/msg00004.html http://lists.gnu.org/archive/html/groff/2005-11/msg00074.html It turns out that Robert was having a problem building CVS groff, which requires texinfo >= 4.8 to compile the info files, under Mac OS X, and configure was saying his texinfo was too old, in spite of him having explicitly just installed texinfo-4.8. The actual problem was that the configure test employed a sed command with this same semicolon usage, and was not behaving as expected -- the test failed because *it* was invalid, *not* because the detected texinfo was too old! At this time, I checked the man page for sed on a SunOS box. Here the documentation very explicitly states that commands in sed scripts *must* be separated by newlines; semicolon is acceptable as an alternative to a comma, to separate the two components of a range specification, but it is *not* acceptable as a command separator. Curiously, the SunOS sed implementation *does* support semicolons as command separators, even though the man page expressly excludes it; it would seem, however, that Mac OS X may be more rigorous in this requirement. To guarantee portability of the above sed command, it cannot be written as shown: `sed -n '/@datadir@/p;/@docdir@/p;/@infodir@/p...' ...` it *must* be rewritten as: `sed -n -e '/@datadir@/p' -e '/@docdir@/p' -e '/@infodir@/p' ...` or as: `sed -n '/@datadir@/p /@docdir@/p /@infodir@/p ...' ...` (i.e. with explicit newlines separating the sed command strings). Regards, Keith.
