Refactor tar(1) manpage

and mark it as finished in the README.
Specifically, add a small section on the compression flags, which
are basically an infected GNU limb which should be removed from
the face of the earth as soon as possible.

README

@@ -65,7 +65,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
    strings         no                              -a, -n, -t
 =* sync            non-posix                       none
 =  tail            no                              -c, -f
-=  tar             non-posix                       none
+=* tar             non-posix                       none
 =* tee             yes                             none
    test            yes                             none
 =  touch           no                              -r

tar.1

@@ -1,4 +1,4 @@
-.Dd January 31, 2015
+.Dd February 8, 2015
 .Dt TAR 1
 .Os sbase
 .Sh NAME
@@ -7,54 +7,65 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl C Ar dir
-.Op Fl jz
-.Fl x Op Fl m
-|
-.Fl t
-.Op Fl f Ar tarfile
+.Op Fl j | Fl z
+.Fl x Op Fl m | Fl t
+.Op Fl f Ar file
 .Nm
 .Op Fl C Ar dir
-.Op Fl jz
+.Op Fl j | Fl z
 .Fl c Ar dir
-.Op Fl f Ar tarfile
+.Op Fl f Ar file
 .Nm
 .Op Fl C Ar dir
-.Op Fl jz
+.Op Fl j | Fl z
 .Fl cf
-.Ar tarfile Ar dir
+.Ar file Ar dir
 .Sh DESCRIPTION
 .Nm
-is the standard file archiver. Generally the archives
-created with it are further compressed.
+is the standard file archiver.
 .Sh OPTIONS
 .Bl -tag -width Ds
 .It Fl c Ar path
-Creates tarball from
+Create archive from
 .Ar path .
 .It Fl C Ar dir
 Change directory to
 .Ar dir
 before beginning.
-.It Fl f Ar tarfile
-Make
-.Ar tarfile
-be the archive, rather than stdin or stdout.
-.It Fl j
-Compress archive using bzip2. The
-.Xr bzip2 1
-utility must be installed separately.
+.It Fl f Ar file
+Set
+.Ar file
+as input | output archive instead of stdin | stdout.
 .It Fl m
 Do not preserve modification time.
 .It Fl t
-List all files in tarball.
+List all files in the archive.
 .It Fl x
-Extract tarball.
-.It Fl z
-Compress archive using gzip. The
+Extract archive.
+.It Fl j | Fl z
+Use bzip2 | gzip compression. The
+.Xr bzip2 1 |
 .Xr gzip 1
-utility must be installed separately.
+utilities must be installed separately.
+Using these flags is discouraged in favour of the flexibility
+and clarity of pipes:
+.Bd -literal -offset indent
+$ bzcat archive.tar.bz2 | tar -x
+$ zcat archive.tar.gz | tar -x
+.Ed
+.Bd -literal -offset indent
+$ tar -c file ... | bzip2 > archive.tar.bz2
+$ tar -c file ... | gzip2 > archive.tar.gz
+.Ed
 .El
 .Sh SEE ALSO
 .Xr ar 1 ,
 .Xr bzip2 1 ,
 .Xr gzip 1
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the UStar (Uniform Standard Tape ARchive)
+format defined in the
+.St -p1003.1-88
+specification.