You really won't find it because it doesn't exist on Android system not even from a third party Busybox installer. But I achieved to find a solution to compile it so that I can use it on my android terminal. Here's the link http://forum.xda-developers.com/showthread.php?t=1612760
Basically you just have to follow this,
Originally posted by samveen on XDA
After wandering around looking for an android build of the file command, I finally went ahead and compiled it myself.
The attached package contains the file binary (v5.11), the libmagic.so shared library, the associated magic files and the build specific files that I needed (over and above the source) to build it. The paths of the files are relative to '/'.
Note: Add the location of libmagic.so to LD_LIBRARY_PATH to get rid of the "CANNOT LINK EXECUTABLE" error. (I use /data/local/lib)
$ echo $ LD_LIBRARY_PATH /data/local/lib:/data/local/lib:/data/local/lib:/system/lib:/vendor/lib
Usage: - file [-bchikLlNnprsvz0] [--apple]
[--mime-type] [-e testname]
[-F separator] [-f namefile]
[-m magicfiles] file ...
file -C [-m magicfiles]
$ getprop | grep device [ro.cm.device]: [jordan] [ro.product.device]: [umts_jordan]
Download here: http://forum.xda-developers.com/attachment.php?attachmentid=1022807&d=1335294084