Find files older than 60 days
find * -mtime +60

Delete files in backup folder which are older than 60 days
rm -f `find /backup/ -mtime +60`

Search for a string inside files
grep -H -r "search me" /var/www

Find files owned by apache user
find /var/www/ -user apache

Find directories owned by apache user
find /var/www/ -user apache -type d

Listing files in a directory
ls -lh

Copy an entire directory (files + subdirectories)
cp -R existingdir/ newdir/

Zip up an entire directory
zip -r zipefilename foldername

Count total number of files in a directory
ls -1 | wc -l
find . -type f | wc -l

Get directory size
du -hs /var/www

Get amount of free disk space available
df -h

Get Linux version details
uname -a
cat /proc/version

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