What is file?
5 file examples
Syntax and Options
Related Commands
What is file?
The file command accepts a file as an argument and performs certain tests to determine the correct file type. For example text, executable etc.
5 file Examples
1. A basic example
The following basic example determines the file type for all the files present in current directory.
$ file * cmd: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xfac3f75dfae01e0ac037c39099182eb5c51fca82, not stripped cmd.c: ASCII English text file: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xcd78d8859677bf20f34fa16142593494b01cd1ee, not stripped file.c: ASCII C program text helloworld.c: ASCII text helloworld.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped input.txt: ASCII text split: directory
2. Change the delimiter using -F option
As can be seen in the above example, the default delimiter between file name and file type is ‘:’. This can be changed using -F option.
Here is an example :
$ file -F - * cmd- ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xfac3f75dfae01e0ac037c39099182eb5c51fca82, not stripped cmd.c- ASCII English text file- ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xcd78d8859677bf20f34fa16142593494b01cd1ee, not stripped file.c- ASCII C program text helloworld.c- ASCII text helloworld.o- ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped input.txt- ASCII text split- directory
3. Determine the file type of stdin using – option
To determine the file type of stdin file, use the ‘-‘ option.
Here is an example :
$ file - Hello World /dev/stdin: ASCII text
4. Represent file type in form of mime-type using -i option
By default, the information related to file type is presented in form of human readable string. This can be changed to mime-type string using -i option.
Here is an example:
$ file -i * cmd: application/x-executable; charset=binary cmd.c: text/plain; charset=us-ascii file: application/x-executable; charset=binary file.c: text/x-c; charset=us-ascii helloworld.c: text/plain; charset=us-ascii helloworld.o: application/x-object; charset=binary input.txt: text/plain; charset=us-ascii split: inode/directory; charset=binary
5. Change alignment of output using -N option
The alignment of the output can be changed in way that there is no padding after file name by using -N option.
Here is an example :
$ file -N * cmd: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xfac3f75dfae01e0ac037c39099182eb5c51fca82, not stripped cmd.c: ASCII English text file: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0xcd78d8859677bf20f34fa16142593494b01cd1ee, not stripped file.c: ASCII C program text helloworld.c: ASCII text helloworld.o: ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped input.txt: ASCII text split: directory
Syntax and Options
file [-bchiklLNnprsvz0] [--apple] [--mime-encoding] [--mime-type]
[-e testname] [-F separator] [-f namefile] [-m magicfiles] file ...
file -C [-m magicfiles]
file [--help]
| Short Option | Long Option | Option Description |
|---|---|---|
| -b | –brief | Do not prepend filenames to output lines (brief mode). |
| -C | –compile | Write a magic.mgc output file that contains a pre-parsed version of the magic file or directory. |
| -c | –checking-printout | Cause a checking printout of the parsed form of the magic file. This is usually used in conjunction with the -m flag to debug a new magic file before installing it. |
| -e | –exclude | Exclude the test named in testname from the list of tests made to determine the file type |
| -F | –separator | Use the specified string as the separator between the filename and the file result returned. Defaults to ‘:’. |
| -h | –no-dereference | option causes symlinks not to be followed (on systems that support symbolic links). This is the default if the environment variable POSIXLY_CORRECT is not defined. |
| -i | –mime | Causes the file command to output mime type strings rather than the more traditional human readable ones. Thus it may say ‘text/plain; charset=us-ascii’ rather than “ASCII text”. |
| -k | –keep-going | Don’t stop at the first match, keep going. Subsequent matches will be have the string ‘12- ’ prepended. (If you want a new-line, see the -r option.) |
Related Commands
magic
hexdump
od
strings