diff --git a/build-box.sh b/build-box.sh
new file mode 100755
index 0000000..65d1e33
--- /dev/null
+++ b/build-box.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+CFLAGS="-s -Os -Wextra -Wall -pedantic"
+CC="cc"
+
+chmod +x ./libmu/build-libmu.sh
+./libmu/build-libmu.sh
+
+cat > mutils.c << EOF
+#include <stdio.h>
+#include <string.h>
+
+$(for i in $(ls src); do
+	f=$(basename $i .c)
+	echo "int "$f"_main(int argc, char **argv);"
+done)
+
+struct cmd {
+	int (*func)(int argc, char **argv);
+	const char *str;
+} cmds[] = {
+$(for i in $(ls src); do
+	f=$(basename $i .c)
+
+	#EDIT SOURCES
+	cat src/$i | sed "s/main(/"$f"_main(/g" > bin/$i
+
+	#MAKE STRUCTURE
+	echo -e "\t{"$f"_main, \"$f\"},"
+done)
+};
+
+int main(int argc, char **argv) {
+	if (argc > 1) {
+		argc--;
+		argv++;
+
+		for (size_t i = 0; i < sizeof(cmds) / sizeof(struct cmd); i++)
+			if (!strcmp(argv[0], cmds[i].str))
+				return cmds[i].func(argc, argv);
+	}
+
+	for (size_t i = 0; i < sizeof(cmds) / sizeof(struct cmd); i++)
+		printf("%s ", cmds[i].str);
+
+	putchar('\n');
+	return 0;
+}
+EOF
+
+echo $CFLAGS | xargs $CC mutils.c bin/*.c obj/*.o -Iconfigs -Ilibmu -omutils
diff --git a/build.sh b/build.sh
index eeb9809..72ff08b 100755
--- a/build.sh
+++ b/build.sh
@@ -1,8 +1,11 @@
 #!/bin/sh
-CFLAGS=-s -Os -Wextra -Wall -pedantic
-CC=cc
+CFLAGS="-s -Os -Wextra -Wall -pedantic"
+CC="cc"
+
+chmod +x ./libmu/build-libmu.sh
+./libmu/build-libmu.sh
 
 for i in $(ls src); do
 	echo "CC $i"
-	$CC $CFLAGS -Iconfigs -Iinclude src/$i -o bin/$(basename $i .c)
+	echo $CFLAGS | xargs $CC -Iconfigs -Ilibmu src/$i -o bin/$(basename $i .c) obj/*.o
 done
diff --git a/clean.sh b/clean.sh
new file mode 100755
index 0000000..7881c8e
--- /dev/null
+++ b/clean.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+rm -f obj/* bin/* mutils.c mutils
diff --git a/configs/config.h b/configs/config.h
index 5959897..112d499 100644
--- a/configs/config.h
+++ b/configs/config.h
@@ -16,8 +16,8 @@
 
 #ifdef _PW_CHECK_H
 	/* Pw_check. Salt for crypt() */
-	int MU_SALT_ENC[] = {'s', 'a', 'l', 't'};
-	char MU_SALT_BUF[sizeof(MU_SALT_ENC) + 1];
+	static int MU_SALT_ENC[] = {'s', 'a', 'l', 't'};
+	static char MU_SALT_BUF[sizeof(MU_SALT_ENC) + 1];
 #endif
 
 #ifdef _MOUNT_C
diff --git a/include/mu_strlen.h b/include/mu_strlen.h
deleted file mode 100644
index ee6463b..0000000
--- a/include/mu_strlen.h
+++ /dev/null
@@ -1,13 +0,0 @@
-#ifndef _UTF8_STRLEN
-#define _UTF8_STRLEN
-
-static size_t mu_strlen(const char *s) {
-	size_t i = 0;
-
-	while (*s++)
-		i += (*s & 0xC0) != 0x80;
-
-	return i;
-}
-
-#endif
diff --git a/libmu/build-libmu.sh b/libmu/build-libmu.sh
new file mode 100755
index 0000000..00b5b67
--- /dev/null
+++ b/libmu/build-libmu.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+cd obj
+cc ../libmu/*.c -I ../configs -I ../libmu -c
diff --git a/include/duration.h b/libmu/duration.c
similarity index 72%
rename from include/duration.h
rename to libmu/duration.c
index ac09e4d..af68748 100644
--- a/include/duration.h
+++ b/libmu/duration.c
@@ -1,9 +1,7 @@
-#ifndef _DURATION_H
-#define _DURATION_H
-
+#include <stdlib.h>
 #include <string.h>
 
-static unsigned long long parse_uint(const char *str) {
+unsigned long long parse_uint(const char *str) {
 	char *p = NULL;
 
 	unsigned long long res = strtoull(str, &p, 0);
@@ -32,7 +30,7 @@ static unsigned long long parse_uint(const char *str) {
 	return res;
 }
 
-static unsigned long long mu_parse_duration(const char *arg) {
+unsigned long long mu_parse_duration(const char *arg) {
 	if (strchr(arg, '.')) {
 		/* TODO */
 	}
@@ -44,5 +42,3 @@ static unsigned long long mu_parse_duration(const char *arg) {
 
 	return 0;
 }
-
-#endif
diff --git a/libmu/duration.h b/libmu/duration.h
new file mode 100644
index 0000000..063aa81
--- /dev/null
+++ b/libmu/duration.h
@@ -0,0 +1,7 @@
+#ifndef _DURATION_H
+#define _DURATION_H
+
+unsigned long long parse_uint(const char *str);
+unsigned long long mu_parse_duration(const char *arg);
+
+#endif
diff --git a/include/get_stat.h b/libmu/get_stat.c
similarity index 58%
rename from include/get_stat.h
rename to libmu/get_stat.c
index 258f9fa..1085922 100644
--- a/include/get_stat.h
+++ b/libmu/get_stat.c
@@ -1,12 +1,9 @@
-#ifndef _GET_STAT_H
-#define _GET_STAT_H
-
 #include <stdio.h>
-#include <errno.h>
 #include <string.h>
-#include <sys/stat.h>
+#include <errno.h>
+#include "get_stat.h"
 
-static int mu_get_stat(const char *prog_name, const char *path, struct stat *stat_path) {
+int mu_get_stat(const char *prog_name, const char *path, struct stat *stat_path) {
 	if (stat(path, stat_path)) {
 		if (prog_name != NULL)
 			fprintf(stderr, "%s: %s: %s\n", prog_name, path, strerror(errno));
@@ -17,7 +14,7 @@ static int mu_get_stat(const char *prog_name, const char *path, struct stat *sta
 	return 0;
 }
 
-static int mu_get_lstat(const char *prog_name, const char *path, struct stat *stat_path) {
+int mu_get_lstat(const char *prog_name, const char *path, struct stat *stat_path) {
 	if (lstat(path, stat_path)) {
 		if (prog_name != NULL)
 			fprintf(stderr, "%s: %s: %s\n", prog_name, path, strerror(errno));
@@ -28,12 +25,10 @@ static int mu_get_lstat(const char *prog_name, const char *path, struct stat *st
 	return 0;
 }
 
-static int mu_get_stats(const char *prog_name, int flag, const char *path, struct stat *stat_path) {
+int mu_get_stats(const char *prog_name, int flag, const char *path, struct stat *stat_path) {
 	if (flag)
 		return mu_get_lstat(prog_name, path, stat_path);
 
 	else
 		return mu_get_stat(prog_name, path, stat_path);
 }
-
-#endif
diff --git a/libmu/get_stat.h b/libmu/get_stat.h
new file mode 100644
index 0000000..c884e62
--- /dev/null
+++ b/libmu/get_stat.h
@@ -0,0 +1,9 @@
+#ifndef _GET_STAT_H
+#define _GET_STAT_H
+
+#include <sys/stat.h>
+int mu_get_stat(const char *prog_name, const char *path, struct stat *stat_path);
+int mu_get_lstat(const char *prog_name, const char *path, struct stat *stat_path);
+int mu_get_stats(const char *prog_name, int flag, const char *path, struct stat *stat_path);
+
+#endif
diff --git a/include/human.h b/libmu/human.c
similarity index 62%
rename from include/human.h
rename to libmu/human.c
index 458358c..6eb052d 100644
--- a/include/human.h
+++ b/libmu/human.c
@@ -1,13 +1,6 @@
-#ifndef _HUMAN_H
-#define _HUMAN_H
+#include "human.h"
 
-#include <stdlib.h>
-#include <stdint.h>
-
-#define MU_HUMAN_BUF_SIZE 16
-
-static char *mu_humansize(off_t n, off_t block) {
-	static char mu_hs_buf[MU_HUMAN_BUF_SIZE + 1];
+char *mu_humansize(off_t n, off_t block) {
 	memset(mu_hs_buf, '\0', sizeof(mu_hs_buf));
 
 	char *postfixes = "BKMGTPE";
@@ -27,4 +20,3 @@ static char *mu_humansize(off_t n, off_t block) {
 	return mu_hs_buf;
 }
 
-#endif
diff --git a/libmu/human.h b/libmu/human.h
new file mode 100644
index 0000000..00f2a50
--- /dev/null
+++ b/libmu/human.h
@@ -0,0 +1,12 @@
+#ifndef _HUMAN_H
+#define _HUMAN_H
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+#define MU_HUMAN_BUF_SIZE 16
+static char mu_hs_buf[MU_HUMAN_BUF_SIZE + 1];
+
+char *mu_humansize(off_t n, off_t block);
+#endif
diff --git a/include/make_path.h b/libmu/make_path.c
similarity index 80%
rename from include/make_path.h
rename to libmu/make_path.c
index 934130b..fa24470 100644
--- a/include/make_path.h
+++ b/libmu/make_path.c
@@ -1,11 +1,8 @@
-#ifndef _MAKE_PATH_H
-#define _MAKE_PATH_H
-
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 
-static char *mu_make_path(const char *prog_name, const char *src, const char *dst) {
+char *mu_make_path(const char *prog_name, const char *src, const char *dst) {
 	int flag = 0;
 
 	if (src == NULL) {
@@ -35,5 +32,3 @@ static char *mu_make_path(const char *prog_name, const char *src, const char *ds
 
 	return full_path;
 }
-
-#endif
diff --git a/libmu/make_path.h b/libmu/make_path.h
new file mode 100644
index 0000000..4687185
--- /dev/null
+++ b/libmu/make_path.h
@@ -0,0 +1,5 @@
+#ifndef _MAKE_PATH_H
+#define _MAKE_PATH_H
+
+char *mu_make_path(const char *prog_name, const char *src, const char *dst);
+#endif
diff --git a/include/mode_to_str.h b/libmu/mode_to_str.c
similarity index 85%
rename from include/mode_to_str.h
rename to libmu/mode_to_str.c
index b34728b..8be70f0 100644
--- a/include/mode_to_str.h
+++ b/libmu/mode_to_str.c
@@ -1,11 +1,8 @@
-#ifndef _MODE_TO_STR_H
-#define _MODE_TO_STR_H
-
 #include <stdio.h>
 #include <sys/stat.h>
+#include "mode_to_str.h"
 
-static char *mu_mode_2_str(mode_t file_mode) {
-	static char mode[11];
+char *mu_mode_2_str(mode_t file_mode) {
 	snprintf(mode, sizeof(mode), "----------");
 
 	if (file_mode & S_IRUSR)
@@ -54,4 +51,3 @@ static char *mu_mode_2_str(mode_t file_mode) {
 	return mode;
 }
 
-#endif
diff --git a/libmu/mode_to_str.h b/libmu/mode_to_str.h
new file mode 100644
index 0000000..34e6152
--- /dev/null
+++ b/libmu/mode_to_str.h
@@ -0,0 +1,6 @@
+#ifndef _MODE_TO_STR_H
+#define _MODE_TO_STR_H
+static char mode[11];
+
+char *mu_mode_2_str(mode_t file_mode);
+#endif
diff --git a/libmu/mu_strlen.c b/libmu/mu_strlen.c
new file mode 100644
index 0000000..13239e5
--- /dev/null
+++ b/libmu/mu_strlen.c
@@ -0,0 +1,11 @@
+#include "mu_strlen.h"
+
+size_t mu_strlen(const char *s) {
+	size_t i = 0;
+
+	while (*s++)
+		i += (*s & 0xC0) != 0x80;
+
+	return i;
+}
+
diff --git a/libmu/mu_strlen.h b/libmu/mu_strlen.h
new file mode 100644
index 0000000..a720249
--- /dev/null
+++ b/libmu/mu_strlen.h
@@ -0,0 +1,6 @@
+#ifndef _MU_STRLEN
+#define _MU_STRLEN
+
+#include <stdio.h>
+size_t mu_strlen(const char *s);
+#endif
diff --git a/include/parse_mode.h b/libmu/parse_mode.c
similarity index 92%
rename from include/parse_mode.h
rename to libmu/parse_mode.c
index 19b4265..806caf9 100644
--- a/include/parse_mode.h
+++ b/libmu/parse_mode.c
@@ -1,6 +1,4 @@
-#ifndef _PARSE_MODE_H
-#define _PARSE_MODE_H
-
+#include <stdlib.h>
 #include <sys/stat.h>
 #include <string.h>
 
@@ -15,7 +13,7 @@
 #define SU_PERM (S_ISUID | S_ISGID | S_ISVTX)
 #define FULL_PERM (WR_PERM | EX_PERM | RD_PERM)
 
-static mode_t mu_parse_mode(const char *s, mode_t cur_mode) {
+mode_t mu_parse_mode(const char *s, mode_t cur_mode) {
 	char *p = NULL;
 
 	mode_t mode = (mode_t)strtol(s, &p, 8);
@@ -96,4 +94,3 @@ static mode_t mu_parse_mode(const char *s, mode_t cur_mode) {
 		return (cur_mode & ~mask) | (mode & mask);
 }
 
-#endif
diff --git a/libmu/parse_mode.h b/libmu/parse_mode.h
new file mode 100644
index 0000000..18e17ff
--- /dev/null
+++ b/libmu/parse_mode.h
@@ -0,0 +1,5 @@
+#ifndef _PARSE_MODE_H
+#define _PARSE_MODE_H
+
+mode_t mu_parse_mode(const char *s, mode_t cur_mode);
+#endif
diff --git a/include/parse_mount.h b/libmu/parse_mount.c
similarity index 54%
rename from include/parse_mount.h
rename to libmu/parse_mount.c
index 1dbcaed..b4ca1ec 100644
--- a/include/parse_mount.h
+++ b/libmu/parse_mount.c
@@ -1,26 +1,7 @@
-#ifndef _PARSE_MOUNT_H
-#define _PARSE_MOUNT_H
 #include <string.h>
+#include "parse_mount.h"
 
-typedef struct {
-	char *opt;
-	char *notopt;
-	char *desc;
-	unsigned int val;
-} MU_MOUNT_OPTS;
-
-static MU_MOUNT_OPTS mu_options[] = {
-	{"defaults", NULL,     NULL, 0},
-	{"ro",       "rw",     "Read only / Read and write", MS_RDONLY},
-	{"remount",  NULL,     "Remount a mounted filesystem", MS_REMOUNT},
-	{"sync",     "async",  "Writes are [a]synchronous", MS_SYNCHRONOUS},
-	{"nodev",    "dev",    "(Dis)allow use of special device files", MS_NODEV},
-	{"bind",     "rbind",  "Bind a file or directory", MS_BIND},
-	{"noexec",   "exec",   "(Dis)allow use of executable files", MS_NOEXEC},
-	{"noatime",  "atime",  "Disable/enable updates to inode access times", MS_NOATIME}
-};
-
-static unsigned long mu_parse_opts(char *str, char *data, const size_t data_size) {
+unsigned long mu_parse_opts(char *str, char *data, const size_t data_size) {
 	memset(data, '\0', data_size);
 	unsigned long opt = 0;
 	size_t data_len = 0;
@@ -68,5 +49,3 @@ static unsigned long mu_parse_opts(char *str, char *data, const size_t data_size
 
 	return opt;
 }
-
-#endif
diff --git a/libmu/parse_mount.h b/libmu/parse_mount.h
new file mode 100644
index 0000000..e0b7e20
--- /dev/null
+++ b/libmu/parse_mount.h
@@ -0,0 +1,24 @@
+#ifndef _PARSE_MOUNT_H
+#define _PARSE_MOUNT_H
+#include <sys/mount.h>
+
+typedef struct {
+	char *opt;
+	char *notopt;
+	char *desc;
+	unsigned int val;
+} MU_MOUNT_OPTS;
+
+static MU_MOUNT_OPTS mu_options[] = {
+	{"defaults", NULL,     NULL, 0},
+	{"ro",       "rw",     "Read only / Read and write", MS_RDONLY},
+	{"remount",  NULL,     "Remount a mounted filesystem", MS_REMOUNT},
+	{"sync",     "async",  "Writes are [a]synchronous", MS_SYNCHRONOUS},
+	{"nodev",    "dev",    "(Dis)allow use of special device files", MS_NODEV},
+	{"bind",     "rbind",  "Bind a file or directory", MS_BIND},
+	{"noexec",   "exec",   "(Dis)allow use of executable files", MS_NOEXEC},
+	{"noatime",  "atime",  "Disable/enable updates to inode access times", MS_NOATIME}
+};
+
+unsigned long mu_parse_opts(char *str, char *data, const size_t data_size);
+#endif
diff --git a/include/proc_parser.h b/libmu/proc_parser.c
similarity index 72%
rename from include/proc_parser.h
rename to libmu/proc_parser.c
index f7a028a..b948a37 100644
--- a/include/proc_parser.h
+++ b/libmu/proc_parser.c
@@ -1,52 +1,13 @@
-#ifndef _PROC_PARSER
-#define _PROC_PARSER
-
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
-#include <limits.h>
 #include <errno.h>
 #include <ctype.h>
-#include <pwd.h>
-#include <grp.h>
+#include "proc_parser.h"
 
-struct mu_proc {
-	/* from status */
-	char prog[PATH_MAX + 1];
-	uid_t uid;
-	gid_t gid;
-
-	/* from stat */
-	pid_t pid;
-	char cmdline[PATH_MAX + 1];
-	char state;
-	int ppid;
-	int pgrp;
-	int sid;
-	int tty;
-	int tpgid;
-	unsigned flags;
-	unsigned long minflt;
-	unsigned long cminflt;
-	unsigned long majflt;
-	unsigned long cmajflt;
-	unsigned long utime;
-	unsigned long stime;
-	long cutime;
-	long cstime;
-	long priority;
-	long nice;
-	long num_threads;
-	long itrealvalue;
-	unsigned long long starttime;
-	unsigned long vsize;
-	long rss;
-	long rsslim;
-};
-
-static int mu_proc_status(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
+int mu_proc_status(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
 	proc_s->uid = -1;
 	proc_s->gid = -1;
 
@@ -98,7 +59,7 @@ static int mu_proc_status(const char *prog_name, const pid_t pid, struct mu_proc
 	return 0;
 }
 
-static int mu_proc_stat(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
+int mu_proc_stat(const char *prog_name, const pid_t pid, struct mu_proc *proc_s) {
 	char path[PATH_MAX + 1];
 	snprintf(path, sizeof(path), "/proc/%d/stat", pid);
 
@@ -132,5 +93,3 @@ int mu_proc_parser(const char *prog_name, const pid_t pid, struct mu_proc *proc_
 
 	return ret;
 }
-
-#endif
diff --git a/libmu/proc_parser.h b/libmu/proc_parser.h
new file mode 100644
index 0000000..cc427dd
--- /dev/null
+++ b/libmu/proc_parser.h
@@ -0,0 +1,45 @@
+#ifndef _PROC_PARSER
+#define _PROC_PARSER
+
+#include <pwd.h>
+#include <grp.h>
+#include <limits.h>
+
+struct mu_proc {
+	/* from status */
+	char prog[PATH_MAX + 1];
+	uid_t uid;
+	gid_t gid;
+
+	/* from stat */
+	pid_t pid;
+	char cmdline[PATH_MAX + 1];
+	char state;
+	int ppid;
+	int pgrp;
+	int sid;
+	int tty;
+	int tpgid;
+	unsigned flags;
+	unsigned long minflt;
+	unsigned long cminflt;
+	unsigned long majflt;
+	unsigned long cmajflt;
+	unsigned long utime;
+	unsigned long stime;
+	long cutime;
+	long cstime;
+	long priority;
+	long nice;
+	long num_threads;
+	long itrealvalue;
+	unsigned long long starttime;
+	unsigned long vsize;
+	long rss;
+	long rsslim;
+};
+
+int mu_proc_status(const char *prog_name, const pid_t pid, struct mu_proc *proc_s);
+int mu_proc_stat(const char *prog_name, const pid_t pid, struct mu_proc *proc_s);
+int mu_proc_parser(const char *prog_name, const pid_t pid, struct mu_proc *proc_s);
+#endif
diff --git a/include/pw_check.h b/libmu/pw_check.c
similarity index 77%
rename from include/pw_check.h
rename to libmu/pw_check.c
index d33dcd2..45c31f5 100644
--- a/include/pw_check.h
+++ b/libmu/pw_check.c
@@ -1,14 +1,11 @@
-#ifndef _PW_CHECK_H
-#define _PW_CHECK_H
-
-#include <pwd.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include "pw_check.h"
 #include "config.h"
 
-static void dec_salt(void) {
+void dec_salt(void) {
 	size_t i;
 	for (i = 0; i < sizeof(MU_SALT_ENC) / sizeof(int); i++)
 		MU_SALT_BUF[i] = (char)MU_SALT_ENC[i];
@@ -16,7 +13,7 @@ static void dec_salt(void) {
 	MU_SALT_BUF[i + 1] = '\0';
 }
 
-static char *enc_password(const char *prog_name, const char *pass, const char *salt) {
+char *enc_password(const char *prog_name, const char *pass, const char *salt) {
 	if (salt == NULL)
 		dec_salt();
 
@@ -31,7 +28,7 @@ static char *enc_password(const char *prog_name, const char *pass, const char *s
 	return cpass;
 }
 
-static int pw_check(const char *prog_name, const struct passwd *pw, const char *pass) {
+int pw_check(const char *prog_name, const struct passwd *pw, const char *pass) {
 	if (pw->pw_passwd[0] == '\0' && pass[0] == '\0')
 		return 0;
 
@@ -55,4 +52,3 @@ static int pw_check(const char *prog_name, const struct passwd *pw, const char *
 	return 1;
 }
 
-#endif
diff --git a/libmu/pw_check.h b/libmu/pw_check.h
new file mode 100644
index 0000000..5554617
--- /dev/null
+++ b/libmu/pw_check.h
@@ -0,0 +1,9 @@
+#ifndef _PW_CHECK_H
+#define _PW_CHECK_H
+#include <pwd.h>
+
+void dec_salt(void);
+char *enc_password(const char *prog_name, const char *pass, const char *salt);
+int pw_check(const char *prog_name, const struct passwd *pw, const char *pass);
+
+#endif
diff --git a/include/recurse.h b/libmu/recurse.c
similarity index 78%
rename from include/recurse.h
rename to libmu/recurse.c
index 4b01146..1edac27 100644
--- a/include/recurse.h
+++ b/libmu/recurse.c
@@ -1,13 +1,11 @@
-#ifndef _RECURSE_H
-#define _RECURSE_H
-
 #include <stdio.h>
 #include <dirent.h>
+#include <stdlib.h>
 #include <string.h>
 #include "make_path.h"
 #include "get_stat.h"
 
-static int mu_recurse(const char *restrict prog_name, int link_flag, const char *restrict path, void *restrict arg, int (*file_act)(const char *path, void *p), int (*dir_act)(const char *path, void *p)) {
+int mu_recurse(const char *restrict prog_name, int link_flag, const char *restrict path, void *restrict arg, int (*file_act)(const char *path, void *p), int (*dir_act)(const char *path, void *p)) {
 	struct stat sb;
 	if (mu_get_stats(prog_name, link_flag, path, &sb))
 		return 1;
@@ -49,5 +47,3 @@ static int mu_recurse(const char *restrict prog_name, int link_flag, const char
 
 	return ret;
 }
-
-#endif
diff --git a/libmu/recurse.h b/libmu/recurse.h
new file mode 100644
index 0000000..ce3dc19
--- /dev/null
+++ b/libmu/recurse.h
@@ -0,0 +1,5 @@
+#ifndef _RECURSE_H
+#define _RECURSE_H
+
+int mu_recurse(const char *restrict prog_name, int link_flag, const char *restrict path, void *restrict arg, int (*file_act)(const char *path, void *p), int (*dir_act)(const char *path, void *p));
+#endif
diff --git a/include/unused.h b/libmu/unused.h
similarity index 100%
rename from include/unused.h
rename to libmu/unused.h
diff --git a/obj/.gitignore b/obj/.gitignore
new file mode 100644
index 0000000..e69de29
diff --git a/src/chgrp.c b/src/chgrp.c
index 982e594..757a475 100644
--- a/src/chgrp.c
+++ b/src/chgrp.c
@@ -4,6 +4,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <dirent.h>
+#include <errno.h>
 #include <sys/stat.h>
 #include "make_path.h"
 #include "get_stat.h"
diff --git a/src/chmod.c b/src/chmod.c
index 5b4bc72..c2f681c 100644
--- a/src/chmod.c
+++ b/src/chmod.c
@@ -3,6 +3,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <dirent.h>
+#include <errno.h>
 #include <sys/stat.h>
 #include "mode_to_str.h"
 #include "make_path.h"
diff --git a/src/env.c b/src/env.c
index 09aa151..331ecf9 100644
--- a/src/env.c
+++ b/src/env.c
@@ -4,7 +4,7 @@
 #include <string.h>
 #include <unistd.h>
 
-int main(const int argc, char **argv, const char **envp) {
+int main(const int argc, char **argv) {
 	int i;
 	for (i = 1; i < argc; i++) {
 		char *val = strchr(argv[i], '=');
@@ -21,10 +21,8 @@ int main(const int argc, char **argv, const char **envp) {
 
 	/* Print env */
 	if (i == argc) {
-		while (*envp)
-			puts(*envp++);
-
-		return 0;
+		fputs("env: not enought opearands\n", stderr);
+		return 1;
 	}
 
 	execvp(argv[i], argv + i);
diff --git a/src/grep.c b/src/grep.c
index 5e48c62..4fbfa0b 100644
--- a/src/grep.c
+++ b/src/grep.c
@@ -11,6 +11,11 @@ typedef struct {
 static PATTERN *regexs;
 static size_t r_size;
 
+static char i_flag;
+static char F_flag;
+static char E_flag;
+static char H_flag;
+
 static int addpattern(char *str) {
 	if (regexs == NULL) {
 		regexs = malloc(sizeof(PATTERN));
@@ -29,16 +34,16 @@ static int addpattern(char *str) {
 	}
 	regexs = regexs_tmp;
 
+	/* Add new pattern */
 	regexs[r_size].pattern = str;
-
+	
 	r_size++;
 	return 0;
 }
 
 int main(int argc, char **argv) {
-
 	int opt;
-	while ((opt = getopt(argc, argv, "e:")) != -1) {
+	while ((opt = getopt(argc, argv, "e:iFH")) != -1) {
 		switch (opt) {
 			case 'e':
 				if (addpattern(optarg))
@@ -46,8 +51,20 @@ int main(int argc, char **argv) {
 
 				break;
 
+			case 'i':
+				i_flag = 1;
+				break;
+
+			case 'F':
+				F_flag = 1;
+				break;
+
+			case 'H':
+				H_flag = 1;
+				break;
+
 			default:
-				printf("grep [e] [FILE]\n\t-e PTRN Pattern to match\n");
+				printf("grep [eiFH] [FILE]\n\t-e PTRN Pattern to match\n\t-i Ignore case\n\t-H Add 'filename:' prefix\n\t-F PATTERN is a literal (not regexp)\n");
 				return 0;
 		}
 	}
diff --git a/src/kill.c b/src/kill.c
index 0748208..bbb7d11 100644
--- a/src/kill.c
+++ b/src/kill.c
@@ -94,7 +94,7 @@ int main(int argc, char **argv) {
 	argc -= optind;
 
 	if ((n_flag || !a_flag) && argc == 0) {
-		fprintf(stderr, "kill: missing operands\n");
+		fputs("kill: missing operands\n", stderr);
 		return 1;
 	}
 
diff --git a/src/ln.c b/src/ln.c
index b7f6c48..c48781d 100644
--- a/src/ln.c
+++ b/src/ln.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 #include <errno.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include "make_path.h"
diff --git a/src/printenv.c b/src/printenv.c
index 860ccae..1542f7c 100644
--- a/src/printenv.c
+++ b/src/printenv.c
@@ -3,7 +3,9 @@
 #include <string.h>
 #include <unistd.h>
 
-static int printvars(int len, char **names) {
+extern char **environ;
+
+static int printvars(int len, char **names, char n_flag) {
 	int ret = 0;
 
 	for (int i = 0; i < len; i++) {
@@ -13,28 +15,38 @@ static int printvars(int len, char **names) {
 			continue;
 		}
 
-		printf("%s\n", val);
+		printf("%s%c", val, n_flag);
 	}
 
 	return ret;
 }
 
-int main(int argc, char **argv, const char **envp) {
+int main(int argc, char **argv) {
+	char n_flag = '\n';
+
 	int opt;
 	while ((opt = getopt(argc, argv, "0")) != -1) {
-		puts("printenv [var1 var2...]");
-		return 0;
+		switch (opt) {
+			case 'n':
+				n_flag = '\0';
+				break;
+
+			default:
+				puts("printenv [var1 var2...]\n\t-0 NUL terminated output\n");
+				return 0;
+		}
 	}
 
 	argv += optind;
 	argc -= optind;
 
-	if (argc == 0)
-		while (*envp)
-			printf("%s\n", *envp++);
+	if (argc == 0) {
+		while (*environ)
+			printf("%s%c", *environ++, n_flag);
+	}
 
 	else
-		return printvars(argc, argv);
+		return printvars(argc, argv, n_flag);
 
 	return 0;
 }
diff --git a/src/rm.c b/src/rm.c
index d5c81da..f362a0c 100644
--- a/src/rm.c
+++ b/src/rm.c
@@ -77,7 +77,7 @@ int main(int argc, char **argv) {
 				break;
 
 			default:
-				puts("rm [rif] [file1 file2...]\n\t-f Force\n\t-r Recursive\n\t-i Print prompt before remove");
+				puts("rm [rif] [file1 file2...]\n\t-f Never prompt\n\t-r Recursive\n\t-i Print prompt before remove");
 				return 0;
 		}
 	}