>> correct diff(1) usage: -u uses a hardcoded context of 3 while only
>> -U takes an argument
>
> I don't think the -U is portable enough:
>
> | [EMAIL PROTECTED]:/u/rse
> | $ /usr/bin/diff -U3 x y
> | /usr/bin/diff: illegal option -- U
> | usage: diff [-bitw] [-c | -e | -f | -h | -n] file1 file2
> | diff [-bitw] [-C number] file1 file2
> | diff [-bitw] [-D string] file1 file2
> | diff [-bitw] [-c | -e | -f | -h | -n] [-l] [-r] [-s] [-S name] directory1
> directory2
>
> The option -u on the other hand exists everywhere AFAIK.
>
I agree with -u but svs used -u3 which is different.
> Where did -u3 break?
>
You asked for it :-)
The most portable combinations are -U3 and -u using OpenPKG.
The second most portable combinations are the same supporting
everything but solaris8 whose operating system diff does not seem
to support unified format at all.
OP = OpenPKG diffutils-2.8.7-2.4.0
OS = Operating System
OP-u3 OP-U3 OP-u OS-u3 OS-U3 OS-u
----- ----- ----- ----- ----- -----
rm1 ix86-solaris10 OK OK OK ERR OK OK
rm2 ix86-debian3.1 ERR OK OK OK OK OK
rm3 ix86-rhel4 ERR OK OK ERR OK OK
rm4 ix86-solaris9 OK OK OK ERR OK OK
rm5 ia64-freebsd5.4 OK OK OK OK OK OK
rm6 amd64-freebsd5.4 OK OK OK OK OK OK
rm7 sparc64-solaris9 OK OK OK ERR OK OK
rm8 sparc64-solaris8 OK OK OK ERR ERR ERR
rm9 sparc64-solaris10 OK OK OK ERR OK OK
vm10 ix86-freebsd6.0 OK OK OK OK OK OK
vm11 ix86-netbsd2.0.2 OK OK OK OK OK OK
vm12 ix86-gentoo1.12.0 ERR OK OK ERR OK OK
vm20 ix86-suse9.3 ERR OK OK ERR OK OK
vm21 ix86-mandriva10.2 ERR OK OK ERR OK OK
vm22 ix86-freebsd4.11 OK OK OK OK OK OK
vm30 ix86-fedora4 ERR OK OK ERR OK OK
vm31 ix86-suse10.0 ERR OK OK ERR OK OK
vm32 ix86-freebsd7.0 OK OK OK OK OK OK
First column references machine names tested in openpkg.NET
which are property of OpenPKG Foundation e.V.
Operating System tests used /bin/diff on
ix86-solaris10, ix86-solaris9, sparc64-solaris10,
sparc64-solaris8, sparc64-solaris9
Operating System tests used /usr/bin/diff on
amd64-freebsd5.4, ia64-freebsd5.4, ix86-debian3.1, ix86-fedora4,
ix86-freebsd4.11, ix86-freebsd6.0, ix86-freebsd7.0,
ix86-gentoo1.12.0, ix86-mandriva10.2, ix86-netbsd2.0.2,
ix86-rhel4, ix86-suse10.0, ix86-suse9.3
A final note on OP-u3 is that as of this writing OpenPKG uses default
behavior of GNU diffutils which in turn tries to conform to the version
of POSIX that is standard for the system, see [1].
[1]
http://www.gnu.org/software/diffutils/manual/html_node/Standards-conformance.html#Standards%20conformance
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