file - determine file type
file [ file ... ]
File performs a series of tests on its argument files in an attempt to classify their con-
tents by language or purpose. If no arguments are given, the classification is performed
on standard input.
The file types it looks for include directory, device file, zero-filled file, empty file,
Plan 9 executable, PAC audio file, cpio archive, tex dvi file, archive symbol table, ar-
chive, rc script, sh script, PostScript, troff output file for various devices, GIF, FAX,
picfile(9.6), object code, C and Alef source, assembler source, compressed files,
encrypted file, English text, Plan 9 bitmap, Plan 9 subfont, Plan 9 font.
If a file has no apparent format, file looks at the character set it uses to classify it
according to ASCII, extended ASCII, Latin ASCII, or UTF holding one or more of the follow-
ing blocks of the Unicode Standard: Extended Latin, Greek, Cyrillic, Armenian, Hebrew,
Arabic, Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil, Telugu, Kannada, Malayalam,
Thai, Lao, Tibetan, Georgian, Japanese, Chinese, or Korean.
If all else fails, file decides its input is binary.
It can make mistakes, for example classifying a file of decimal data, etc. as troff(1)