Rename threading flag to -t,--threads + update man page

ncdu.1

@@ -18,6 +18,7 @@
 .Op Fl \-include\-caches , \-exclude\-caches
 .Op Fl L , \-follow\-symlinks , \-no\-follow\-symlinks
 .Op Fl \-include\-kernfs , \-exclude\-kernfs
+.Op Fl t , \-threads Ar num
 .Op Fl 0 , 1 , 2
 .Op Fl q , \-slow\-ui\-updates , \-fast\-ui\-updates
 .Op Fl \-enable\-shell , \-disable\-shell
@@ -147,6 +148,16 @@ The exact counting behavior of this flag is subject to change in the future.
 .Pp
 The complete list of currently known pseudo filesystems is: binfmt, bpf, cgroup,
 cgroup2, debug, devpts, proc, pstore, security, selinux, sys, trace.
+.It Fl t , \-threads Ar num
+Number of threads to use when scanning the filesystem, currently defaults to 1.
+.Pp
+In single-threaded mode, the export function (see
+.Fl o )
+can operate with very little memory, but in multi-threaded mode the entire
+directory tree is first constructed in memory and written out after the
+filesystem scan has completed,
+This causes a delay in output and requires significantly more memory for large
+directory trees.
 .El
 .Ss Interface Options
 .Bl -tag -width Ds
@@ -159,9 +170,8 @@ When exporting the data with
 ncurses will not be initialized at all.
 This option is the default when exporting to standard output.
 .It Fl 1
-Similar to
+Write progress information to the terminal, but don't open a full-screen
-.Fl 0 ,
+ncurses interface.
-but does give feedback on the scanning progress with a single line of output.
 This option is the default when exporting to a file.
 .Pp
 In some cases, the ncurses browser interface which you'll see after the

src/main.zig

@@ -266,6 +266,9 @@ fn argConfig(args: *Args, opt: Args.Option) bool {
         else if (std.mem.eql(u8, val, "dark")) config.ui_color = .dark
         else if (std.mem.eql(u8, val, "dark-bg")) config.ui_color = .darkbg
         else ui.die("Unknown --color option: {s}.\n", .{val});
+    } else if (opt.is("-t") or opt.is("--threads")) {
+        const val = args.arg();
+        config.threads = std.fmt.parseInt(u8, val, 10) catch ui.die("Invalid number of --threads: {s}.\n", .{val});
     } else return false;
     return true;
 }
@@ -329,6 +332,7 @@ fn help() noreturn {
     \\  -v,-V,--version            Print version
     \\  -x                         Same filesystem
     \\  -e                         Enable extended information
+    \\  -t NUM                     Number of threads to use
     \\  -r                         Read only
     \\  -o FILE                    Export scanned directory to FILE
     \\  -f FILE                    Import scanned directory from FILE
@@ -487,7 +491,6 @@ pub fn main() void {
             else if (opt.is("-f")) import_file = allocator.dupeZ(u8, args.arg()) catch unreachable
             else if (opt.is("--ignore-config")) {}
             else if (opt.is("--quit-after-scan")) quit_after_scan = true // undocumented feature to help with benchmarking scan/import
-            else if (opt.is("--experimental-threads")) config.threads = std.fmt.parseInt(u8, args.arg(), 10) catch ui.die("Invalid number of threads.\n", .{})
             else if (argConfig(&args, opt)) {}
             else ui.die("Unrecognized option '{s}'.\n", .{opt.val});
         }