Enable and document the -Z option for selecting "compress" compression,

now that libarchive supports it.

usr.bin/tar/bsdtar.1

@@ -405,6 +405,15 @@ Note that, unlike other
 .Nm tar
 implementations, this implementation recognizes gzip compression
 automatically when reading archives.
+.It Fl Z
+(c mode only)
+Compress the resulting archive with
+.Xr compress 1 .
+In extract or list modes, this option is ignored.
+Note that, unlike other
+.Nm tar
+implementations, this implementation recognizes compress compression
+automatically when reading archives.
 .El
 .Sh ENVIRONMENT
 The following environment variables affect the execution of
@@ -628,6 +637,7 @@ an archive while preserving any absolute pathnames,
 components, or symlinks to other directories.
 .Sh SEE ALSO
 .Xr bzip2 1 ,
+.Xr compress 1 ,
 .Xr cpio 1 ,
 .Xr gzip 1 ,
 .Xr mt 1 ,

usr.bin/tar/bsdtar.c

@@ -624,11 +624,6 @@ main(int argc, char **argv)
 	if (bsdtar->option_warn_links)
 		only_mode(bsdtar, "--check-links", "cr");
 
-	/* Check other parameters only permitted in certain modes. */
-	if (bsdtar->create_compression == 'Z' && bsdtar->mode == 'c') {
-		bsdtar_warnc(bsdtar, 0, ".Z compression not supported");
-		usage(bsdtar);
-	}
 	if (bsdtar->create_compression != '\0') {
 		strcpy(buff, "-?");
 		buff[1] = bsdtar->create_compression;

usr.bin/tar/write.c

@@ -220,6 +220,9 @@ tar_mode_c(struct bsdtar *bsdtar)
 			archive_write_set_compression_gzip(a);
 			break;
 #endif
+		case 'Z':
+			archive_write_set_compression_compress(a);
+			break;
 		default:
 			bsdtar_errc(bsdtar, 1, 0,
 			    "Unrecognized compression option -%c",