Linux Command Learning Summary: File command

http://www.cnblogs.com/kerrycode/p/3806618.htmlLinux Command Learning Summary: File command

Introduction to Commands:

This command is used to identify file types and to identify the encoding format of some files. It does this by looking at the header information of the file to get the file type, rather than identifying the file type as Windows does by extension.

Execute permissions: All User

Instruction Path:/usr/bin/file

Command syntax:

file [-BCHIKLNNPRSVZ] [-F NameFile] [-F separator] [-M magicfiles] file ...

Command parameters:

The following table lists some of the commonly used parameters.

Parameters	Long parameters	Description
-B		When listing file identification results, the file name is not displayed.
-C		Detailed instruction execution process to facilitate troubleshooting or analysis of program execution scenarios
-F		List file types for file names in files
-F		Replaces the default ":" Delimiter after the output file name with the specified separator symbol.
-I.		Output MIME-type string
-L		View file types for corresponding soft link files
-Z		Try to interpret the contents of a compressed file
	--help	Show Commands online Help
	--version	Display Command version information

Examples of Use:

1: View the Help information for the file command

[[Email protected] ~] # file--help

Usage:file [OPTION] ... [FILE] ...

Determine file type of FILEs.

  -M,--magic-file list use      list as a colon-separated list of magic

                               Number files

  -Z,--uncompress try to look           inside compressed files

  -B,--brief do not                prepend filenames to output lines

  -C,--checking-printout in    

                               conjunction with-m to debug a new magic file

                               Before installing it

  -F,--files-from FILE read the filenames to is      examined from file

  -F,--separator string use     string as separator instead of ': '

  -I,--mime                 output MIME type strings

  -K,--keep-going           don ' t stop at the first match

  -L,--dereference          causes symlinks to be followed

  -N,--no-buffer do not            buffer output

  -N,--no-pad do not               pad output

  -P,--preserve-date        preserve access times on files

  -R,--raw                  don ' t translate unprintable chars to \ooo

  -S,--special-files        treat Special (Block/char devices) files as

                             Ordinary ones

      --help Display this help and                 exit

      --version              output version information and exit

Of course you can also use the man file to get more detailed help document information.

2: View File types

For example, as shown below, the Temp.txt file type is text, encoded as UTF-8 Unicode

[[Email protected] ~]

Temp.txt:utf-8 Unicode text, with very long lines, with CRLF line terminators

3: Do not output file name, only show file format and encoding

With the following two commands, you can clearly understand the role of parameter-B.

[[Email protected] ~]

Temp.txt:utf-8 Unicode text, with very long lines, with CRLF line terminators

[[Email protected] ~] # file-b Temp.txt

UTF-8 Unicode text, with very long lines, with CRLF line terminators

4: Output MIME-type string

[[Email protected] ~]

Temp.txt:text/plain; Charset=utf-8

5: View file types for file names in files

This parameter is ideal for Shell scripting to find and discriminate data for a file type.

[[Email protected] ~] # cat >test

It is only one test file

[2]+  Stopped                 cat > Test

[[Email protected] ~] # file-f  Test

/root/install.log:        ASCII text

It is only one test File:ERROR:cannot open ' It was only one test file ' (No such file or directory)

[[Email protected] ~]

5: Replaces the default ":" Delimiter after the output file name with the specified separator symbol.

Feel this parameter is very chicken! I was puzzled when I understood the function of this parameter.

6: Try to interpret the contents of the compressed file

[[Email protected] ~]

"Temp.txt", from Unix, last modified:tue June 24 00:34:15 2014)

7: View the file type of the soft link file

As shown below, create a soft-link sfile, and then view the file with the file-l with the parameter separately

[[Email protected] ~] # ln-s Temp.txt.gz sfile

[[Email protected] ~]

Sfile:symbolic link to ' Temp.txt.gz '

[[Email protected] ~]

"Temp.txt", from Unix, last modified:tue June 24 00:34:15 2014

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Linux Command Learning Summary: File command