Useful commands, so I don't have to keep looking

handy_shell.md

Useful shell commands

Shell

• Find which directories are the disk hogs

  du --max-depth=1 -h | sort -h

• Copy a mysql database from one server to another via ssh

  mysqldump -u root -pPASSWORD --all-databases | ssh [email protected] 'cat - | mysql -u root -pPASSWORD'

  Note, you must restart the target mysql server afterwards, and if you do you may get the error "ERROR 1045 (28000): Access denied for user 'debian-sys-maint'@'localhost'" (on debian at least).

  Fix this by executing the command:

  GRANT ALL PRIVILEGES ON *.* TO 'debian-sys-maint'@'localhost' IDENTIFIED BY 'THE PASSWORD' WITH GRANT OPTION;

  Where 'THE PASSWORD' is the password found in /etc/mysql/debian.cnf

• Message users on a remote server

  echo "message" | ssh user@host wall

  or

  echo "message" | ssh user@host sudo wall

  to send something as the admin.

Mail servers

• How many messages are there in the queue?

exim -bpc

• Test routing to an address (useful for problem diagnosis)

exim -bt [email protected]

• Restarting a mail queue and attempt redelivery

exim -q -v

• Thaw all messages

exim -bp | grep -i frozen | awk '{print $3}' | while read LINE; do exim -Mt $LINE; done

Ubuntu EC2 Instances

• Rsync files to server as root user

rsync -Pavz -e "ssh -i KEYPAIR.pem" --rsync-path "sudo rsync" LOCALFILES ubuntu@HOSTNAME:REMOTEDIR/

Squid

• Remove a URL from cache / force refresh

  squidclient -m PURGE http://url

Elgg

• Find all translation content containing a string (in this case "Friend")

  find . -name en.php | xargs -i{} cat {} | egrep "=.["|'][f|F]riend*"