I’ve received about 300 images in CR2 (Canon raw image format) and wanted to convert it to jpg.
Here is a solution working on Ubuntu 12.04 LTS:

1. Install  libjpeg-turbo-progs, dcraw and ufraw.
2. You can use ufraw for displaying and enhancing a single image.
3. If you want to convert large number of files you can use following Perl script with dcraw tool:

   #!/usr/bin/perl     opendir (DIR, "."); @files= readdir(DIR); foreach $file (@files){ next unless $file =~ /([^\.]*)\.CR2$/; print "Converting $file\n"; system("dcraw -c $file | cjpeg > $1.jpg"); }

   #!/usr/bin/perl opendir (DIR, "."); @files= readdir(DIR); foreach $file (@files){ next unless $file =~ /([^\.]*)\.CR2$/; print "Converting $file\n"; system("dcraw -c $file | cjpeg > $1.jpg"); }