find

search for any text file in home dir
find /home/gus -name *.txt

omit cache files
find /home/gus -name *.txt | grep -v .cache

only include files (from current dir)
find . -name Documents -type f

only include dirs (from current dir)
find . -name Documents -type d

delete files (from current dir)
find . -name Documents -type f -exec rm {} +

remove execution permission on files in Pictures dir
find Pictures/ -type f -exec chmod 600 {} +

set permissions on Pictures dir
find Pictures/ -type d -exec chmod 700 {} +

example, clear logs
ls -l /var/log

test / dryrun
sudo find /var/log -type f -name *.log

if results look ok, execute
sudo find /var/log -type f -name *.log -exec truncate -s 0 {} +

find any mp3 file in home dir and save to file
find . -name *.mp3 > music.txt