diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0366f8a..16e2822 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,11 @@
 # 0.0.1
 * catを追加
 * cpを追加
+* echoを追加（完了）
+* groupsを追加（完了）
 * lsを追加
 * mkdirを追加（完了）
 * pwdを追加（完了）
 * rmを追加（完了）
 * touchを追加
+* whoamiを追加（完了）
diff --git a/echo.zig b/echo.zig
new file mode 100644
index 0000000..9b53c3e
--- /dev/null
+++ b/echo.zig
@@ -0,0 +1,85 @@
+const std = @import("std");
+const io = std.io;
+const os = std.os;
+
+const version = @import("version.zig").version;
+
+fn help() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("076 coreutils\n", .{});
+    try stdout.print("使用法: echo\n", .{});
+    try stdout.print("文章を表示\n\n", .{});
+    try stdout.print("-h ヘルプを表示\n", .{});
+    try stdout.print("-v バージョンを表示\n", .{});
+    try stdout.print("-n ニューラインを見逃す\n", .{});
+
+    try bw.flush();
+}
+
+fn ver() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("echo (076 coreutils) {s}\n", .{version});
+
+    try bw.flush();
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const alloc = gpa.allocator();
+
+    var option = std.ArrayList(u8).init(alloc);
+    defer option.deinit();
+
+    const args = try std.process.argsAlloc(alloc);
+    defer std.process.argsFree(alloc, args);
+    var text: [1024]u8 = undefined;
+    var text_len: usize = 0;
+
+    for (args, 0..) |arg, i| {
+        if (i == 0) continue;
+        var m: [1]u8 = [_]u8{'-'};
+        if (std.mem.eql(u8, arg[0..1], m[0..])) {
+            for (arg, 0..) |a, j| {
+                if (j == 0) continue;
+                try option.append(a);
+            }
+        } else {
+            const length = std.math.min(arg.len, text.len - 1);
+            std.mem.copy(u8, text[0..length], arg[0..length]);
+            text_len = length;
+        }
+    }
+
+    var isnonl = false;
+    for (option.items) |i| {
+        if (i == 'h') {
+            try help();
+            return;
+        }
+        if (i == 'v') {
+            try ver();
+            return;
+        }
+        if (i == 'n') {
+            isnonl = true;
+        }
+    }
+
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    if (isnonl) {
+        try stdout.print("{s}", .{text[0..text_len]});
+    } else {
+        try stdout.print("{s}\n", .{text[0..text_len]});
+    }
+    try bw.flush();
+}
diff --git a/groups.zig b/groups.zig
new file mode 100644
index 0000000..e0b6eb7
--- /dev/null
+++ b/groups.zig
@@ -0,0 +1,165 @@
+const std = @import("std");
+const fs = std.fs;
+const io = std.io;
+const os = std.os;
+const mem = std.mem;
+
+const version = @import("version.zig").version;
+
+fn help() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("076 coreutils\n", .{});
+    try stdout.print("使用法: groups\n", .{});
+    try stdout.print("グループ名を表示\n\n", .{});
+    try stdout.print("-h ヘルプを表示\n", .{});
+    try stdout.print("-v バージョンを表示\n", .{});
+
+    try bw.flush();
+}
+
+fn ver() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("groups (076 coreutils) {s}\n", .{version});
+
+    try bw.flush();
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const alloc = gpa.allocator();
+
+    var option = std.ArrayList(u8).init(alloc);
+    defer option.deinit();
+
+    const args = try std.process.argsAlloc(alloc);
+    defer std.process.argsFree(alloc, args);
+    var username: [32]u8 = undefined;
+
+    for (args, 0..) |arg, i| {
+        if (i == 0) continue;
+        var m: [1]u8 = [_]u8{'-'};
+        if (mem.eql(u8, arg[0..1], m[0..])) {
+            for (arg, 0..) |a, j| {
+                if (j == 0) continue;
+                try option.append(a);
+            }
+        } else {
+            const length = std.math.min(arg.len, username.len - 1);
+            mem.copy(u8, username[0..length], arg[0..length]);
+            username[length] = 0;
+        }
+    }
+
+    for (option.items) |i| {
+        if (i == 'h') {
+            try help();
+            return;
+        }
+        if (i == 'v') {
+            try ver();
+            return;
+        }
+    }
+
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+    var buf: [4096]u8 = undefined;
+
+    if (username[0] == 0) {
+        const pfile = try fs.cwd().openFile("/etc/passwd", .{});
+        defer pfile.close();
+
+        const pstream = pfile.reader();
+        const preal = try pstream.readAll(&buf);
+
+        var plines = mem.split(u8, buf[0..preal], "\n");
+        while (plines.next()) |*line| {
+            var fields = mem.split(u8, line.*, ":");
+            var username_opt = fields.next();
+            _ = fields.next();
+            var uid_str_opt = fields.next();
+            if (username_opt != null and uid_str_opt != null) {
+                const puid = std.fmt.parseInt(u32, uid_str_opt.?, 10) catch continue;
+                if (puid == os.linux.getuid()) {
+                    if (username_opt) |username_slice| {
+                        mem.copy(u8, username[0..], username_slice);
+                    }
+                    break;
+                }
+            }
+        }
+    }
+
+    const cwd = fs.cwd();
+
+    const file = try cwd.openFile("/etc/group", .{});
+    defer file.close();
+
+    const stream = file.reader();
+    const real = try stream.readAll(&buf);
+    var user_found_in_group = false;
+
+    var lines = mem.split(u8, buf[0..real], "\n");
+    while (lines.next()) |*line| {
+        var fields = mem.split(u8, line.*, ":");
+        var group_opt = fields.next();
+        _ = fields.next();
+        _ = fields.next();
+        var users_str_opt = fields.next();
+        if (group_opt != null and users_str_opt != null) {
+            var users = mem.split(u8, users_str_opt.?, ",");
+            while (users.next()) |user| {
+                var user_length: usize = 0;
+                while (user[user_length] != ':' and user[user_length] != '\n') : (user_length += 1) {}
+                var username_length: usize = 0;
+                while (username[username_length] != 0) : (username_length += 1) {}
+
+                if (mem.eql(u8, user[0..user_length], username[0..username_length])) {
+                    try stdout.print("{s} ", .{group_opt.?});
+                }
+            }
+        }
+    }
+
+    var it = mem.split(u8, buf[0..real], "\n");
+    while (it.next()) |line| {
+        user_found_in_group = false;
+        var split = mem.split(u8, line, ":");
+
+        if (split.next()) |group| {
+            var group_length: usize = 0;
+            while (group[group_length] != ':' and group[group_length] != '\n') : (group_length += 1) {}
+            var username_length: usize = 0;
+            while (username[username_length] != 0) : (username_length += 1) {}
+
+            if (split.next()) |_| {
+                if (split.next()) |_| {
+                    if (split.next()) |users| {
+                        var users_list = mem.split(u8, users, ",");
+                        while (users_list.next()) |user| {
+                            var user_length: usize = 0;
+                            while (user[user_length] != ':' and user[user_length] != '\n') : (user_length += 1) {}
+                            if (std.mem.eql(u8, user[0..user_length], username[0..username_length])) {
+                                user_found_in_group = true;
+                            }
+                        }
+                    }
+                }
+            }
+
+            if (std.mem.eql(u8, group[0..group_length], username[0..username_length]) and !user_found_in_group) {
+                try stdout.print("{s} ", .{group});
+            }
+        }
+    }
+    try stdout.print("\n", .{});
+    try bw.flush();
+}
diff --git a/whoami.zig b/whoami.zig
new file mode 100644
index 0000000..eb5d794
--- /dev/null
+++ b/whoami.zig
@@ -0,0 +1,91 @@
+const std = @import("std");
+const fs = std.fs;
+const io = std.io;
+const os = std.os;
+
+const version = @import("version.zig").version;
+
+fn help() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("076 coreutils\n", .{});
+    try stdout.print("使用法: whoami\n", .{});
+    try stdout.print("ユーザー名を表示\n\n", .{});
+    try stdout.print("-h ヘルプを表示\n", .{});
+    try stdout.print("-v バージョンを表示\n", .{});
+
+    try bw.flush();
+}
+
+fn ver() !void {
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    try stdout.print("whoami (076 coreutils) {s}\n", .{version});
+
+    try bw.flush();
+}
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const alloc = gpa.allocator();
+
+    var option = std.ArrayList(u8).init(alloc);
+    defer option.deinit();
+
+    const args = try std.process.argsAlloc(alloc);
+    defer std.process.argsFree(alloc, args);
+
+    for (args, 0..) |arg, i| {
+        if (i == 0) continue;
+        var m: [1]u8 = [_]u8{'-'};
+        if (std.mem.eql(u8, arg[0..1], m[0..])) {
+            for (arg, 0..) |a, j| {
+                if (j == 0) continue;
+                try option.append(a);
+            }
+        }
+    }
+
+    for (option.items) |i| {
+        if (i == 'h') {
+            try help();
+            return;
+        }
+        if (i == 'v') {
+            try ver();
+            return;
+        }
+    }
+
+    const stdof = io.getStdOut().writer();
+    var bw = io.bufferedWriter(stdof);
+    const stdout = bw.writer();
+
+    const file = try fs.cwd().openFile("/etc/passwd", .{});
+    defer file.close();
+
+    var buf: [4096]u8 = undefined;
+    const stream = file.reader();
+    const real = try stream.readAll(&buf);
+
+    var lines = std.mem.split(u8, buf[0..real], "\n");
+    while (lines.next()) |*line| {
+        var fields = std.mem.split(u8, line.*, ":");
+        var username_opt = fields.next();
+        _ = fields.next();
+        var uid_str_opt = fields.next();
+        if (username_opt != null and uid_str_opt != null) {
+            const puid = std.fmt.parseInt(u32, uid_str_opt.?, 10) catch continue;
+            if (puid == os.linux.getuid()) {
+                try stdout.print("{s}\n", .{username_opt.?});
+                try bw.flush();
+                return;
+            }
+        }
+    }
+}