Here’s a list of Linux commands I found very useful throughout the years. You might want to bookmark it as you’ll surely need it again someday.

Archive files of folders:

tar -czf new-tar-file-name.tar.gz file-or-folder-to-archive
tar -czf new-tar-file-name.tar.gz file1 file2 folder1 folder2

Unarchive:

tar -xzf tar-file-name.tar.gz

List and sort files by size:

ls -lS
ls -lSr

List folder sizes:

du -sh /*

Show free disk space:

df -h

Count all the files and folders in a directory:

ls | wc -l

Rename a file or folder:

mv name new_name

Remove an entire folder, with all its content:

rm -rf dir_name

Create a symlink:

ln -s [TARGET DIRECTORY OR FILE] ./[SHORTCUT]
E.g.:
ln -s /usr/local/apache/logs ./logs

Convert windows stye line-endings to unix style for an entire project:

This command will skip the .git and .svn directories but you can adapt it to your needs:
find . -path ./.git -prune -o -path ./*.svn -prune -o -print -exec dos2unix {} ;

Find files containing text:

grep -rnw 'directory' -e "pattern"
and here’s an example:
grep -rnw /etc/apache2/sites-available/ -e "www"

Find (then delete) .svn folders form your project:

find . -name .svn -exec echo {} ;
find . -name .svn -exec rm -rf {} ;