file

# file The file command is "a file type guesser", that is, a command-line tool that tells you in words what kind of data a file contains. Unlike most GUI systems, command-line UNIX systems - with this program leading the charge - don't rely on filename extentions to tell you the type of a file, but look at the file's actual contents. This is, of course, more reliable, but requires a bit of I/O. ## Examples ``` $ file logo logo: Adobe Photoshop Image, 2457 x 3425, RGB, 3x 8-bit channels ``` ``` $ file INSTALL INSTALL: ReStructuredText file, ASCII text ``` ## Usage ``` $ file --help Usage: file [OPTION...] [FILE...] Determine type of FILEs. --help display this help and exit -v, --version output version information and exit -m, --magic-file LIST use LIST as a colon-separated list of magic number files -z, --uncompress try to look inside compressed files -Z, --uncompress-noreport only print the contents of compressed files -b, --brief do not prepend filenames to output lines -c, --checking-printout print the parsed form of the magic file, use in conjunction with -m to debug a new magic file before installing it -e, --exclude TEST exclude TEST from the list of test to be performed for file. Valid tests are: apptype, ascii, cdf, compress, csv, elf, encoding, soft, tar, json, simh, text, tokens --exclude-quiet TEST like exclude, but ignore unknown tests -f, --files-from FILE read the filenames to be examined from FILE -F, --separator STRING use string as separator instead of `:' -i, --mime output MIME type strings (--mime-type and --mime-encoding) --apple output the Apple CREATOR/TYPE --extension output a slash-separated list of extensions --mime-type output the MIME type --mime-encoding output the MIME encoding -k, --keep-going don't stop at the first match -l, --list list magic strength -n, --no-buffer do not buffer output -N, --no-pad do not pad output -0, --print0 terminate filenames with ASCII NUL -P, --parameter set file engine parameter limits bytes 7340032 max bytes to look inside file elf_notes 256 max ELF notes processed elf_phnum 2048 max ELF prog sections processed elf_shnum 32768 max ELF sections processed elf_shsize 134217728 max ELF section size encoding 65536 max bytes to scan for encoding indir 50 recursion limit for indirection name 50 use limit for name/use magic regex 8192 length limit for REGEX searches -r, --raw don't translate unprintable chars to \ooo -s, --special-files treat special (block/char devices) files as ordinary ones -S, --no-sandbox disable system call sandboxing -C, --compile compile file specified by -m -d, --debug print debugging messages Report bugs to https://bugs.astron.com/ ```