===== Change file/folder permission (chown) ===== ==== Using "number-mode" ==== ''print('hello world')'' 
chmod {owner} - {group} - {other} filename
==== Search for files and chown them ==== use "find . -type d ..." for directorys): find . -type f -not \( -name "file1.txt" -o -name "file2.lol" -o -name "file3.\*" \) -print0 | xargs -0 chown [username] ---- ===== Find files containing text ===== grep -rwl "search-string" /path/to/serch/dir ===== Working with external storage ===== === Mount USB: === 
sudo fdisk -l
sudo mount -t vfat /dev/...
===== Ejabberd ===== === Delete chat === 
$ ejabberdctl remove_mam_for_user_with_peer maxmustermann your.address admin@somepi.ddns.net
===== Show free diskspace ===== 
$ sudo df -h
===== Working with .tar archives ===== === Compress === 
$ tar -czvf name-of-archive.tar.gz /path/to/directory-or-file
=== Extract === 
$ tar -xzvf archive.tar.gz -C /path/to/extract
* x extract * v verbos * f files * c compress * z use gzip compression * -C output path ===== MYSQL ===== === Reset auto_incerement to 0 === 
MYSQL > ALTER TABLE [YOUR_TABLE] auto_increment = 0;
=== IMPORT DUMP FILE === 
$ sudo mysql -u root -p [DATABASE] < [DUMP_FILE].sql
=== Show the path to database files === 
$ sudo mysql -u root -p -e "SELECT @@datadir;"
=== SHOW ALL USERS === 
MYSQL > SELECT User, Host, Password FROM mysql.user;