[Samsung Galaxy Mini] Paul L.:
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symlink("busybox", "/system/xbin/[", "/system/xbin/[[",
"/system/xbin/adjtimex", "/system/xbin/arp", "/system/xbin/ash",
"/system/xbin/awk", "/system/xbin/base64", "/system/xbin/basename",
"/system/xbin/bbconfig", "/system/xbin/blkid", "/system/xbin/blockdev",
"/system/xbin/brctl", "/system/xbin/bunzip2", "/system/xbin/bzcat",
"/system/xbin/bzip2", "/system/xbin/cal", "/system/xbin/cat",
"/system/xbin/catv", "/system/xbin/chattr", "/system/xbin/chgrp",
"/system/xbin/chmod", "/system/xbin/chown", "/system/xbin/chroot",
"/system/xbin/clear", "/system/xbin/cmp", "/system/xbin/comm",
"/system/xbin/cp", "/system/xbin/cpio", "/system/xbin/crond",
"/system/xbin/crontab", "/system/xbin/cut", "/system/xbin/date",
"/system/xbin/dc", "/system/xbin/dd", "/system/xbin/depmod",
"/system/xbin/devmem", "/system/xbin/df", "/system/xbin/diff",
"/system/xbin/dirname", "/system/xbin/dmesg", "/system/xbin/dnsd",
"/system/xbin/dos2unix", "/system/xbin/du", "/system/xbin/echo",
"/system/xbin/ed", "/system/xbin/egrep", "/system/xbin/env",
"/system/xbin/expand", "/system/xbin/expr", "/system/xbin/false",
"/system/xbin/fdisk", "/system/xbin/fgrep", "/system/xbin/find",
"/system/xbin/flash_lock", "/system/xbin/flash_unlock",
"/system/xbin/flashcp", "/system/xbin/flock", "/system/xbin/fold",
"/system/xbin/free", "/system/xbin/freeramdisk", "/system/xbin/fsync",
"/system/xbin/ftpget", "/system/xbin/ftpput", "/system/xbin/fuser",
"/system/xbin/getopt", "/system/xbin/grep", "/system/xbin/groups",
"/system/xbin/gunzip", "/system/xbin/gzip", "/system/xbin/halt",
"/system/xbin/head", "/system/xbin/hexdump", "/system/xbin/id",
"/system/xbin/ifconfig", "/system/xbin/inetd", "/system/xbin/insmod",
"/system/xbin/install", "/system/xbin/iostat", "/system/xbin/ip",
"/system/xbin/kill", "/system/xbin/killall", "/system/xbin/killall5",
"/system/xbin/length", "/system/xbin/less", "/system/xbin/ln",
"/system/xbin/losetup", "/system/xbin/ls", "/system/xbin/lsattr",
"/system/xbin/lsmod", "/system/xbin/lsusb", "/system/xbin/lzcat",
"/system/xbin/lzma", "/system/xbin/lzop", "/system/xbin/lzopcat",
"/system/xbin/man", "/system/xbin/md5sum", "/system/xbin/mesg",
"/system/xbin/mkdir", "/system/xbin/mke2fs", "/system/xbin/mkfifo",
"/system/xbin/mkfs.ext2", "/system/xbin/mkfs.vfat",
"/system/xbin/mknod", "/system/xbin/mkswap", "/system/xbin/mktemp",
"/system/xbin/modinfo", "/system/xbin/modprobe", "/system/xbin/more",
"/system/xbin/mount", "/system/xbin/mountpoint", "/system/xbin/mpstat",
"/system/xbin/mv", "/system/xbin/nanddump", "/system/xbin/nandwrite",
"/system/xbin/netstat", "/system/xbin/nice", "/system/xbin/nohup",
"/system/xbin/nslookup", "/system/xbin/ntpd", "/system/xbin/od",
"/system/xbin/patch", "/system/xbin/pgrep", "/system/xbin/pidof",
"/system/xbin/ping", "/system/xbin/pkill", "/system/xbin/pmap",
"/system/xbin/poweroff", "/system/xbin/printenv", "/system/xbin/printf",
"/system/xbin/ps", "/system/xbin/pstree", "/system/xbin/pwd",
"/system/xbin/pwdx", "/system/xbin/rdev", "/system/xbin/readlink",
"/system/xbin/realpath", "/system/xbin/renice", "/system/xbin/reset",
"/system/xbin/resize", "/system/xbin/rev", "/system/xbin/rm",
"/system/xbin/rmdir", "/system/xbin/rmmod", "/system/xbin/route",
[B][U][SIZE="5"]"/system/xbin/run-parts"[/SIZE][/U][/B], "/system/xbin/rx", "/system/xbin/sed",
"/system/xbin/seq", "/system/xbin/setconsole", "/system/xbin/setserial",
"/system/xbin/setsid", "/system/xbin/sh", "/system/xbin/sha1sum",
"/system/xbin/sha256sum", "/system/xbin/sha512sum",
"/system/xbin/sleep", "/system/xbin/sort", "/system/xbin/split",
"/system/xbin/stat", "/system/xbin/strings", "/system/xbin/stty",
"/system/xbin/sum", "/system/xbin/swapoff", "/system/xbin/swapon",
"/system/xbin/sync", "/system/xbin/sysctl", "/system/xbin/tac",
"/system/xbin/tail", "/system/xbin/tar", "/system/xbin/taskset",
"/system/xbin/tee", "/system/xbin/telnet", "/system/xbin/telnetd",
"/system/xbin/test", "/system/xbin/tftp", "/system/xbin/tftpd",
"/system/xbin/time", "/system/xbin/timeout", "/system/xbin/top",
"/system/xbin/touch", "/system/xbin/tr", "/system/xbin/traceroute",
"/system/xbin/true", "/system/xbin/ttysize", "/system/xbin/tune2fs",
"/system/xbin/umount", "/system/xbin/uname", "/system/xbin/uncompress",
"/system/xbin/unexpand", "/system/xbin/uniq", "/system/xbin/unix2dos",
"/system/xbin/unlzma", "/system/xbin/unlzop", "/system/xbin/unxz",
"/system/xbin/unzip", "/system/xbin/uptime", "/system/xbin/usleep",
"/system/xbin/uudecode", "/system/xbin/uuencode", "/system/xbin/vi",
"/system/xbin/watch", "/system/xbin/wc", "/system/xbin/wget",
"/system/xbin/which", "/system/xbin/whoami", "/system/xbin/xargs",
"/system/xbin/xz", "/system/xbin/xzcat", "/system/xbin/yes",
"/system/xbin/zcat");

(in updater script)

So, busybox is symlinked to run-parts (in fact, run-parts is busybox), the only thing missing is the symlink (this is done when we install the ROM)

The file you copied is a symlink to busybox. :)