File Extension Guesser

A bash script to identify files with a tampered extension by making an educated guess based on the MIME type.

Usage

./extension_guesser.sh [OPTIONS] FILE [FILE ...]

Options:

• -r, --rename: Rename file(s) to the correct extension
• -v, --verbose: Print more information about each file
• -h, --help: Print this help message and exit

Example:

./extension_guesser.sh --verbose --rename *.jpg

This command will check all files with the .jpg extension in the current directory. For each file that has a suspicious extension, the script will suggest a new extension and rename the file.

Condensed oneliner

Not in need for fancy coloured output and automated renaming? Try this oneliner instead:

for file in *; do exts=`grep "$(file -b --mime-type $file)\s" /etc/mime.types | sed 's/\s/ /g' | tr -s ' ' | cut -d ' ' -f 1 --complement`; ext=`echo "$file" | cut -d "." -f 2`; if [[ ! "$exts[@]" =~ "$ext" ]]; then echo "$file should be `echo $exts | awk '{printf $1}'`";fi;done