Question

This is a question regarding Unix shell scripting (any shell), but any other "standard" scripting language solution would also be appreciated:

I have a directory full of files where the filenames are hash values like this:

fd73d0cf8ee68073dce270cf7e770b97 fec8047a9186fdcc98fdbfc0ea6075ee 

These files have different original file types such as png, zip, doc, pdf etc.

Can anybody provide a script that would rename the files so they get their appropriate file extension, probably based on the output of the file command?

Answer:

J.F. Sebastian’s script will work for both ouput of the filenames as well as the actual renaming.

Answer 1

Here’s mimetypes’ version:

#!/usr/bin/env python '''It is a `filename -> filename.ext` filter.      `ext` is mime-based.  ''' import fileinput import mimetypes import os import sys from subprocess import Popen, PIPE  if len(sys.argv) > 1 and sys.argv[1] == '--rename':     do_rename = True     del sys.argv[1] else:     do_rename = False      for filename in (line.rstrip() for line in fileinput.input()):     output, _ = Popen(['file', '-bi', filename], stdout=PIPE).communicate()     mime = output.split(';', 1)[0].lower().strip()     ext = mimetypes.guess_extension(mime, strict=False)     if ext is None:         ext = os.path.extsep + 'undefined'     filename_ext = filename + ext     print filename_ext     if do_rename:        os.rename(filename, filename_ext) 

Example:

 $ ls *.file? | python add-ext.py --rename avi.file.avi djvu.file.undefined doc.file.dot gif.file.gif html.file.html ico.file.obj jpg.file.jpe m3u.file.ksh mp3.file.mp3 mpg.file.m1v pdf.file.pdf pdf.file2.pdf pdf.file3.pdf png.file.png tar.bz2.file.undefined 

---

Following @Phil H’s response that follows @csl’ response:

#!/usr/bin/env python '''It is a `filename -> filename.ext` filter.      `ext` is mime-based. ''' # Mapping of mime-types to extensions is taken form here: # http://as3corelib.googlecode.com/svn/trunk/src/com/adobe/net/MimeTypeMap.as mime2exts_list = [     ['application/andrew-inset','ez'],     ['application/atom+xml','atom'],     ['application/mac-binhex40','hqx'],     ['application/mac-compactpro','cpt'],     ['application/mathml+xml','mathml'],     ['application/msword','doc'],     ['application/octet-stream','bin','dms','lha','lzh','exe','class','so','dll','dmg'],     ['application/oda','oda'],     ['application/ogg','ogg'],     ['application/pdf','pdf'],     ['application/postscript','ai','eps','ps'],     ['application/rdf+xml','rdf'],     ['application/smil','smi','smil'],     ['application/srgs','gram'],     ['application/srgs+xml','grxml'],     ['application/vnd.adobe.apollo-application-installer-package+zip','air'],     ['application/vnd.mif','mif'],     ['application/vnd.mozilla.xul+xml','xul'],     ['application/vnd.ms-excel','xls'],     ['application/vnd.ms-powerpoint','ppt'],     ['application/vnd.rn-realmedia','rm'],     ['application/vnd.wap.wbxml','wbxml'],     ['application/vnd.wap.wmlc','wmlc'],     ['application/vnd.wap.wmlscriptc','wmlsc'],     ['application/voicexml+xml','vxml'],     ['application/x-bcpio','bcpio'],     ['application/x-cdlink','vcd'],     ['application/x-chess-pgn','pgn'],     ['application/x-cpio','cpio'],     ['application/x-csh','csh'],     ['application/x-director','dcr','dir','dxr'],     ['application/x-dvi','dvi'],     ['application/x-futuresplash','spl'],     ['application/x-gtar','gtar'],     ['application/x-hdf','hdf'],     ['application/x-javascript','js'],     ['application/x-koan','skp','skd','skt','skm'],     ['application/x-latex','latex'],     ['application/x-netcdf','nc','cdf'],     ['application/x-sh','sh'],     ['application/x-shar','shar'],     ['application/x-shockwave-flash','swf'],     ['application/x-stuffit','sit'],     ['application/x-sv4cpio','sv4cpio'],     ['application/x-sv4crc','sv4crc'],     ['application/x-tar','tar'],     ['application/x-tcl','tcl'],     ['application/x-tex','tex'],     ['application/x-texinfo','texinfo','texi'],     ['application/x-troff','t','tr','roff'],     ['application/x-troff-man','man'],     ['application/x-troff-me','me'],     ['application/x-troff-ms','ms'],     ['application/x-ustar','ustar'],     ['application/x-wais-source','src'],     ['application/xhtml+xml','xhtml','xht'],     ['application/xml','xml','xsl'],     ['application/xml-dtd','dtd'],     ['application/xslt+xml','xslt'],     ['application/zip','zip'],     ['audio/basic','au','snd'],     ['audio/midi','mid','midi','kar'],     ['audio/mpeg','mp3','mpga','mp2'],     ['audio/x-aiff','aif','aiff','aifc'],     ['audio/x-mpegurl','m3u'],     ['audio/x-pn-realaudio','ram','ra'],     ['audio/x-wav','wav'],     ['chemical/x-pdb','pdb'],     ['chemical/x-xyz','xyz'],     ['image/bmp','bmp'],     ['image/cgm','cgm'],     ['image/gif','gif'],     ['image/ief','ief'],     ['image/jpeg','jpg','jpeg','jpe'],     ['image/png','png'],     ['image/svg+xml','svg'],     ['image/tiff','tiff','tif'],     ['image/vnd.djvu','djvu','djv'],     ['image/vnd.wap.wbmp','wbmp'],     ['image/x-cmu-raster','ras'],     ['image/x-icon','ico'],     ['image/x-portable-anymap','pnm'],     ['image/x-portable-bitmap','pbm'],     ['image/x-portable-graymap','pgm'],     ['image/x-portable-pixmap','ppm'],     ['image/x-rgb','rgb'],     ['image/x-xbitmap','xbm'],     ['image/x-xpixmap','xpm'],     ['image/x-xwindowdump','xwd'],     ['model/iges','igs','iges'],     ['model/mesh','msh','mesh','silo'],     ['model/vrml','wrl','vrml'],     ['text/calendar','ics','ifb'],     ['text/css','css'],     ['text/html','html','htm'],     ['text/plain','txt','asc'],     ['text/richtext','rtx'],     ['text/rtf','rtf'],     ['text/sgml','sgml','sgm'],     ['text/tab-separated-values','tsv'],     ['text/vnd.wap.wml','wml'],     ['text/vnd.wap.wmlscript','wmls'],     ['text/x-setext','etx'],     ['video/mpeg','mpg','mpeg','mpe'],     ['video/quicktime','mov','qt'],     ['video/vnd.mpegurl','m4u','mxu'],     ['video/x-flv','flv'],     ['video/x-msvideo','avi'],     ['video/x-sgi-movie','movie'],     ['x-conference/x-cooltalk','ice']]  #NOTE: take only the first extension mime2ext = dict(x[:2] for x in mime2exts_list)  if __name__ == '__main__':     import fileinput, os.path     from subprocess import Popen, PIPE      for filename in (line.rstrip() for line in fileinput.input()):         output, _ = Popen(['file', '-bi', filename], stdout=PIPE).communicate()         mime = output.split(';', 1)[0].lower().strip()         print filename + os.path.extsep + mime2ext.get(mime, 'undefined') 

---

Here’s a snippet for old python’s versions (not tested):

#NOTE: take only the first extension mime2ext = {} for x in mime2exts_list:     mime2ext[x[0]] = x[1]  if __name__ == '__main__':     import os     import sys      # this version supports only stdin (part of fileinput.input() functionality)     lines = sys.stdin.read().split('\n')     for line in lines:         filename = line.rstrip()         output = os.popen('file -bi ' + filename).read()                 mime = output.split(';')[0].lower().strip()         try: ext = mime2ext[mime]         except KeyError:              ext = 'undefined'         print filename + '.' + ext 

It should work on Python 2.3.5 (I guess).