Category: Linux
How to list all PostgreSQL databases and their sizes in MB
You must provide proper database name and user: File: gistfile1.txt ——————- psql -c “SELECT pg_database.datname, pg_database_size(pg_database.datname), pg_size_pretty(pg_database_size(pg_database.datname)) FROM pg_database ORDER BY pg_database_size DESC;” -d
How to find Raspberry Pi using MAC address
When you want to find your headless but networked Raspberry Pi and you’re lazy like me use nmap: sudo nmap -sP 192.168.1.0/24 | awk ‘/^Nmap/{ip=$NF}/B8:27:EB/{print ip}’ Mask /24 means that addresses from 192.168.1.0 to 192.168.1.254 will be searched. You can extend that to /16 if you don’t know subnet of your device.
Permission denied when script is trying to execute ps_files_cleanup_dir
This is pretty common problem. I’ve encountered it on recent version of the Debian operating system. When you see something like that: Notice: session_start(): ps_files_cleanup_dir: opendir(/var/lib/php5/sessions) failed: Permission denied (13) in /mnt/www-data/htdocs/raportMNW/inc/bryanjhv/slim-session/src/Slim/Middleware/Session.php on line 110 You can fix that easily with following Linux commands: sudo nano /etc/php5/apache2/php.ini Now use CTRL+W to find following string session.save_path and configure it […]
How to delete file permanently in Linux?
Most of Linux distributions have shred already installed. So it’s really easy to delete a file in a secure manner: shred -u -z -n 26 topsecret.txt Meaning of used switches: -n [N] Overwrite a file N times. For example, -n 20 will perform twenty passes over the file’s contents. -u Remove the file after you’ve shredded it. […]