Ubuntu – How to recursively and automatically convert all bmp images to png files in a given directory

for f in $(find . -iname "*.jpg" -type f) ;
    do
    convert $f $(dirname $f)/$(basename -s .jpg $f).png ;
    done

• find . -iname "*.jpg" -type f : search for file ending with ".jpg" case insensitive
• $(dirname $f) : relative path to the folder containing file $f
• $(basename -s .jpg $f) : filename without the suffix ".jpg"

In old Ubuntu basename may need to be run with different way:

basename $f .jpg

Convert is a part of imagemagick (As reference see Batch Processing tif images: Converting .tif to .jpeg) , to install

sudo apt-get install imagemagick

Using find:

find ~/tmp -type f -mtime +0 -delete

• ~/tmp is the directory to be searched recursively, change this accordingly

• -type f will look for only files

• -mtime +0 which will match a file if it was last modified one day or more ago

• -delete will just remove the matched file(s)

Here the catch is -mtime +0, most might think of using -mtime +1 but find will ignore any fractional time while calculating days. So, -mtime +1 will match a file if the last modification was made at least 2 days ago.

Quoting man find, -mtime has the same timing convention as -atime:

-atime n

File was last accessed n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago.

Also note that if you want precision, you should look at the -mmin option of find to indicate time in minutes.

To run it periodically after 3 hours, you can add a cron entry.

Run crontab -e and add:

00 */3 * * * /usr/bin/find ~/tmp -type f -mtime +0 -delete

Using zsh to remove the files:

rm ~/tmp/**/*(.-m+0)

Adding to cron:

00 */3 * * * /usr/bin/zsh -c 'rm ~/tmp/**/*(.-m+0)'