https://wiki.bash-hackers.org/ Update PostgreSQL ------------------------------------------------------------------------------------------------------------ wget -q https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | sudo apt-key add - sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ `lsb_release -cs`-pgdg main" >> /etc/apt/sources.list.d/pgdg.list' sudo apt-get update sudo apt-get install postgres-10 sudo su - postgres psql Set PSQL defaults ------------------------------------------------------------------------------------------------------------- put .psqlrc in home directory \set x '\\setenv PAGER less' \set xx '\\setenv PAGER \'pspg -bX --no-mouse\'' Size of directory: `du -hcs //mnt/c/PostgreSQL/cassandra30/` list lines in file `wc file` General tasks ------------------------------------------------------------------------------------------------------------ wc - print line counts free - memory usage du - disk space by file Resource Limit -------------------------------------------------------------------------------------------------------------- `ulimit -a` to see all limits file at /etc/security/limits.conf to configure defaults MySQL --------------------------------------------------------------------------------------------------------------- connection like `mysql -u root -p` `show databases;` user is in the format root@127.0.0.1 `grant all prviileges on *.* to 'root'@'127.0.0.1'` data is stored in /var/lib/mysql failure to drop a db can be due to presence of unknown file in the database directory SSH ---------------------------------------------------------------------------------------------------------------- add client * client uses ssh-keygen to create a key in `/home/un/.ssh/` under files `id_rsa` and `id_rsa.pub` * host setup //etc/ssh/sshd_config to allow passwords and restart * client uses `ssh-copy-id host_address -p port_num` to move the key to the host * client uses `ssh` to login