Some more useful linux commands

Check machine for open ports, running services, guess OS:
$ sudo nmap -O

Check applictaion running:
$ nc 8983
And the type GET (+enter) to get a response.

Unzip multiple gzipped SQL-files and stream them directly into your mysql database:
$ gzip -cd db_123.sql.gz  db_123_[234567].sql.gz | mysql -u<db_user> -p<db_pass> <db_name>

List each dir-size in human readable format to find the big files:
$ du -hsc

List each file greater 10MB recursively:
$ find . -size +10000k -exec du -h {} ;

Set a yourself a userfriendly commandline editor before you do things like $ corontab -e:
$ export EDITOR=/usr/bin/nano

When copying or (un)zipping large files, instead of re-emitting commands to see progress, use watch and relax:
$ watch -d -n 5 ls -lh

List files without user:group and size:
$ find lsis/sources/bionity/2013/03/28/ -type f -print