exiftool(1p) -b -ThumbnailImage /home/marcos/DCIM/347CANON/_MG_4757.JPG > 4757_thumbnail.jpg
Read and write meta information in files
-b (-binary)
     Output requested data in binary format without tag names or descriptions.  This option is mainly
     used for extracting embedded images or other binary data, but it may also be useful for some text
     strings since control characters (such as newlines) are not replaced by '.' as they are in the
     default output.  Also valid in combination with the "-X" option.
-T (-table)
     Output tag values in table form.  Equivalent to -t -S -q -f.
-h (-htmlFormat)
     Use HTML table formatting for output.  Implies the -E option.  The formatting options -D, -H, -g,
     -G, -l and -s may be used in combination with -h to influence the HTML format.
-u (-unknown)
     Extract values of unknown tags.  Add another -u to also extract unknown information from binary data
     blocks.  This option applies to tags with numerical tag ID's, and causes tag names like
     "Exif_0xc5d9" to be generated for unknown information.  It has no effect on information types which
     have human-readable tag ID's (such as XMP), since unknown tags are extracted automatically from
     these formats.
-m (-ignoreMinorErrors)
     Ignore minor errors and warnings.  This enables writing to files with minor errors and disables some
     validation checks which could result in minor warnings.  Generally, minor errors/warnings indicate a
     problem which usually won't result in loss of metadata if ignored.  However, there are exceptions,
     so ExifTool leaves it up to you to make the final decision.
-n (--printConv)
     Read and write values as numbers instead of words.  By default, extracted values are converted to a
     more human-readable format for printing, but the -n option disables this print conversion for all
     tags.  For example:
  -a          (-duplicates)        Allow duplicate tags to be extracted
  -e          (--composite)        Do not calculate composite tags
  -ee         (-extractEmbedded)   Extract information from embedded files
  -ext EXT    (-extension)         Process files with specified extension
  -F[OFFSET]  (-fixBase)           Fix the base for maker notes offsets
  -fast[NUM]                       Increase speed for slow devices
  -fileOrder [-]TAG                Set file processing order
  -i DIR      (-ignore)            Ignore specified directory name
  -if EXPR                         Conditionally process files
  -m          (-ignoreMinorErrors) Ignore minor errors and warnings
  -o OUTFILE  (-out)               Set output file or directory name
  -overwrite_original              Overwrite original by renaming tmp file
  -overwrite_original_in_place     Overwrite original by copying tmp file
  -P          (-preserve)          Preserve date/time of original file
  -password PASSWD                 Password for processing protected files
  -q          (-quiet)             Quiet processing
  -r          (-recurse)           Recursively process subdirectories
  -scanForXMP                      Brute force XMP scan
  -u          (-unknown)           Extract unknown tags
  -U          (-unknown2)          Extract unknown binary tags too
  -z          (-zip)               Read/write compressed information

Special features
-i DIR (-ignore)
     Ignore specified directory name.  Use multiple -i options to ignore more than one directory name.  A
     special DIR value of "SYMLINKS" (case sensitive) may be specified to ignore symbolic links when the
     -r option is used.
-l (-long)
     Use long 2-line Canon-style output format.  Adds a description and unconverted value to the XML
     output when -X is used.
-e (--composite)
     Extract existing tags only -- don't calculate composite tags.
Before a command is executed, its input and output may be redirected using a special notation interpreted
by  the  shell.   Redirection  may  also  be used to open and close files for the current shell execution
environment.  The following redirection operators may precede or appear anywhere within a simple  command
or may follow a command.  Redirections are processed in the order they appear, from left to right.

Redirecting Output
    Redirection of output causes the file whose name results from the expansion of  word  to  be  opened  for
    writing  on  file descriptor n, or the standard output (file descriptor 1) if n is not specified.  If the
    file does not exist it is created; if it does exist it is truncated to zero size.

    The general format for redirecting output is:

           [n]>word

    If the redirection operator is >, and the noclobber option to the  set  builtin  has  been  enabled,  the
    redirection  will  fail if the file whose name results from the expansion of word exists and is a regular
    file.  If the redirection operator is >|, or the redirection operator is > and the  noclobber  option  to
    the  set  builtin  command  is  not  enabled, the redirection is attempted even if the file named by word
    exists.
source manpages: exiftool