--- /dev/null
+diff -urN busybox.old/include/applets.h busybox.dev/include/applets.h
+--- busybox.old/include/applets.h 2006-03-14 09:46:09.000000000 +0100
++++ busybox.dev/include/applets.h 2006-03-14 09:49:17.000000000 +0100
+@@ -340,6 +340,9 @@
+ #ifdef CONFIG_LOADKMAP
+ APPLET(loadkmap, loadkmap_main, _BB_DIR_SBIN, _BB_SUID_NEVER)
+ #endif
++#ifdef CONFIG_LOCK
++ APPLET_NOUSAGE("lock", lock_main, _BB_DIR_BIN, _BB_SUID_NEVER)
++#endif
+ #ifdef CONFIG_LOGGER
+ APPLET(logger, logger_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
+ #endif
+diff -urN busybox.old/miscutils/Config.in busybox.dev/miscutils/Config.in
+--- busybox.old/miscutils/Config.in 2004-08-27 01:12:59.000000000 +0200
++++ busybox.dev/miscutils/Config.in 2006-03-14 09:52:13.000000000 +0100
+@@ -148,6 +148,12 @@
+ Enables the 'hdparm -d' option to get/set using_dma flag.
+ This is dangerous stuff, so you should probably say N.
+
++config CONFIG_LOCK
++ bool "lock"
++ default y
++ help
++ Small utility for using locks in scripts
++
+ config CONFIG_MAKEDEVS
+ bool "makedevs"
+ default n
+diff -urN busybox.old/miscutils/Makefile.in busybox.dev/miscutils/Makefile.in
+--- busybox.old/miscutils/Makefile.in 2004-10-08 09:45:39.000000000 +0200
++++ busybox.dev/miscutils/Makefile.in 2006-03-14 09:52:41.000000000 +0100
+@@ -31,6 +31,7 @@
+ MISCUTILS-$(CONFIG_DEVFSD) += devfsd.o
+ MISCUTILS-$(CONFIG_HDPARM) += hdparm.o
+ MISCUTILS-$(CONFIG_LAST) += last.o
++MISCUTILS-$(CONFIG_LOCK) += lock.o
+ MISCUTILS-$(CONFIG_MAKEDEVS) += makedevs.o
+ MISCUTILS-$(CONFIG_MT) += mt.o
+ MISCUTILS-$(CONFIG_RX) += rx.o
+diff -urN busybox.old/miscutils/lock.c busybox.dev/miscutils/lock.c
+--- busybox.old/miscutils/lock.c 1970-01-01 01:00:00.000000000 +0100
++++ busybox.dev/miscutils/lock.c 2006-03-14 09:50:40.000000000 +0100
+@@ -0,0 +1,125 @@
++#include <sys/types.h>
++#include <sys/file.h>
++#include <sys/stat.h>
++#include <signal.h>
++#include <fcntl.h>
++#include <unistd.h>
++#include <stdio.h>
++#include "busybox.h"
++
++static int unlock = 0;
++static int shared = 0;
++static int waitonly = 0;
++static int fd;
++static char *file;
++
++static void usage(char *name)
++{
++ fprintf(stderr, "Usage: %s [-suw] <filename>\n"
++ " -s Use shared locking\n"
++ " -u Unlock\n"
++ " -w Wait for the lock to become free, don't acquire lock\n"
++ "\n", name);
++ exit(1);
++}
++
++static void exit_unlock(int sig)
++{
++ flock(fd, LOCK_UN);
++ unlink(file);
++ exit(0);
++}
++
++static int do_unlock(void)
++{
++ FILE *f;
++ int i;
++
++ f = fopen(file, "r");
++ fscanf(f, "%d", &i);
++ if (i > 0)
++ kill(i, SIGTERM);
++ fclose(f);
++
++ return 0;
++}
++
++static int do_lock(void)
++{
++ int pid;
++ char pidstr[8];
++
++ if ((fd = open(file, O_RDWR | O_CREAT, 0700)) < 0) {
++ fprintf(stderr, "Can't open %s\n", file);
++ return 1;
++ }
++
++ if (flock(fd, (shared ? LOCK_SH : LOCK_EX)) < 0) {
++ fprintf(stderr, "Can't lock %s\n", file);
++ return 1;
++ }
++
++ pid = fork();
++
++ if (pid < 0)
++ return -1;
++
++ if (pid == 0) {
++ signal(SIGKILL, exit_unlock);
++ signal(SIGTERM, exit_unlock);
++ signal(SIGINT, exit_unlock);
++ if (waitonly)
++ exit_unlock(0);
++ else
++ while (1)
++ sleep(1);
++ } else {
++ if (!waitonly) {
++ lseek(fd, 0, SEEK_SET);
++ ftruncate(fd, 0);
++ sprintf(pidstr, "%d\n", pid);
++ write(fd, pidstr, strlen(pidstr));
++ close(fd);
++ }
++
++ return 0;
++ }
++}
++
++#ifndef CONFIG_LOCK
++int main(int argc, char **argv)
++#else
++int lock_main(int argc, char **argv)
++#endif
++{
++ char **args = &argv[1];
++ int c = argc - 1;
++
++ while ((*args != NULL) && (*args)[0] == '-') {
++ char *ch = *args;
++ while (*(++ch) > 0) {
++ switch(*ch) {
++ case 'w':
++ waitonly = 1;
++ break;
++ case 's':
++ shared = 1;
++ break;
++ case 'u':
++ unlock = 1;
++ break;
++ }
++ }
++ c--;
++ args++;
++ }
++
++ if (c != 1)
++ usage(argv[0]);
++
++ file = *args;
++ if (unlock)
++ return do_unlock();
++ else
++ return do_lock();
++}