How to list only JPEG files from root below using the command line?

Question

I am searching for a method to find only JPEG files/ With my limited knowledge of Linux I came to this point:

1. list all paths that exist from root below with find /
2. pipe the result into next command and perform the file command on each found path with xargs file
3. In the result of the file command is a JPEG string contained, I thought maybe it would be possible somehow to an IF-statement to filter only the JPEGs: If (JPEG contained in output of file command) {show argument of file}

once more:

find / | xargs file | "If statement" 

Could you please correct me, give me a hint how to perform the task or give a solution?

Answer 1

If you want to list files containing a JPEG image regardless of the extension in the filename, you could use find + file to list the files with mime type image/jpeg:

find . -type f -exec sh -c '
    file --mime-type "$0" | grep -q image/jpeg\$ && printf "$0\n"
' {} \;

or

find . -type f -exec sh -c '
    mt=$(file --brief --mime-type "$0")
    [ -z "${mt#image/jpeg}" ] && printf "$0\n"
' {} \;

Answer 2

As a start, you could print out files with a .jpg file extension with:

sudo find / -name *.jpg -print

See how that behaves, modify to suit, and you can then pipe the output into another function rather than just printout if you'd like. For example, if you want to allow .JPG as well:

sudo find / -iname "*.jpg"

Answer 3

This will print the paths to all files with the mime-type of image/jpeg.

find / -type f -exec file --no-pad --mime-type {} + 2>/dev/null \
    | awk '$NF == "image/jpeg" {$NF=""; sub(": $", ""); print}'

A few things to note:

• use -exec command {} + instead of -exec command {} \; so as to only call file once (instead of once for every file)
• use the --no-pad option to ensure file's output is in a consistent format (to make parsing it easier)
• use 2>/dev/null to suppress stderr of find, only necessary because running the command from / will result in numerous 'Permission denied' errors that will clutter the console