Usage:
file file ...
The command file can be used to determine the file type and its character encoding.

• Display file type:
  $ echo "Hello ..." > file1 $ ln -s file1 sfile1 $ ln file1 hfile1 $ echo "" > file2 $ touch file3 $ echo '#!/bin/bash' > script1.sh; chmod 755 script1.sh $ mkdir folder1
  $ ls -l ./ -rw-rw-r-- 2 10 file1 -rw-rw-r-- 1 1 file2 -rw-rw-r-- 1 0 file3 drwxrwxr-x 2 4096 folder1 -rw-rw-r-- 2 10 hfile1 -rwxr-xr-x 1 12 script1.sh lrwxrwxrwx 1 5 sfile1 -> file1
  $ file ./* ./file1: ASCII text ./file2: very short file (no magic) ./file3: empty ./folder1: directory ./hfile1: ASCII text ./script1.sh: Bourne-Again shell script, ASCII text executable ./sfile1: symbolic link to file1
  You can use the option -i to display mime type and encoding of the file:
  $ file -i ./* ./file1: text/plain; charset=us-ascii ./file2: application/octet-stream; charset=binary ./file3: inode/x-empty; charset=binary ./folder1: inode/directory; charset=binary ./hfile1: text/plain; charset=us-ascii ./script1.sh: text/x-shellscript; charset=us-ascii ./sfile1: inode/symlink; charset=binary
  You can also use the command file to display the file type of an executable binary file (display the OS information and the libraries the executable requires):
  $ file -i /usr/lib/jvm/java-11-openjdk-amd64/bin/java /usr/lib/jvm/java-11-openjdk-amd64/bin/java: application/x-sharedlib; charset=binary
  $ file /usr/lib/jvm/java-11-openjdk-amd64/bin/java /usr/lib/jvm/java-11-openjdk-amd64/bin/java: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=0bae0045bc544e2d1ef0c59e0d7951e880e7aacd, stripped

The following options can be used:
--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, elf, encoding, soft, tar, text, tokens -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 -L, --dereference follow symlinks (default if POSIXLY_CORRECT is set) -h, --no-dereference don't follow symlinks (default if POSIXLY_CORRECT is not set) (default) -n, --no-buffer do not buffer output -N, --no-pad do not pad output -0, --print0 terminate filenames with ASCII NUL -p, --preserve-date preserve access times on files -P, --parameter set file engine parameter limits indir 15 recursion limit for indirection name 30 use limit for name/use magic elf_notes 256 max ELF notes processed elf_phnum 128 max ELF prog sections processed elf_shnum 32768 max ELF sections processed -r, --raw don't translate unprintable chars to \ooo -s, --special-files treat special (block/char devices) files as ordinary ones -C, --compile compile file specified by -m -d, --debug print debugging messages