UNIX – nixCraft

How to display countdown timer in bash shell script running on Linux/Unix

June 24, 2017June 24, 2017in BASH Shell, Linux, UNIX last updated June 24, 2017

I want to display a countdown before purging cache from CDN network. Is there an existing command to show a conuntdown from 30..1 as 30,29,28,…1 on Linux or Unix bash shell script?

How to add ZIL write and L2ARC read cache SSD devices in FreeNAS

June 24, 2017in File system, FreeBSD, FreeNAS, UNIX last updated June 24, 2017

How do I add the write cache called the ZIL and read cache called L2ARC to my my zroot volume? How do I extend my existing zroot volume with ZIL and L2ARC ssd disks of FreNSA server?

How to find and delete directory recursively on Linux or Unix-like system

June 20, 2017June 22, 2017in BASH Shell, Linux, UNIX last updated June 22, 2017

I type ‘find . -type d -iname foo -delete‘ command to find the foo directories and delete them. However, I am getting an error message that read as find: cannot delete './hourly.4/data/foo': Directory not empty on Linux server. How do delete directories based on find command output on Linux or Unix-like system?

How to run cron job every minute on Linux/Unix

June 18, 2017June 18, 2017in BASH Shell, Commands, Linux, UNIX last updated June 18, 2017

I want to run a cron job that should run a specific shell script /home/jobs/sync.cache.sh every minute. How do I use crontab to execute script every minute on Linux or Unix-like system?

How to redirect non-www to www HTTP / TLS /SSL traffic on Nginx

June 17, 2017June 17, 2017in Linux, Nginx, UNIX last updated June 17, 2017

I want ALL cyberciti.biz to go to www.cyberciti.biz for SEO and other reasons. I want ALL HTTP traffic to go to HTTPS. How do I redirect all HTTP/HTTPS non-www (e.g. domain name cyberciti.biz) traffic to www (e.g. domain name www.cyberciti.biz) when using Nginx web server?

How to prevent sed -i command overwriting my symlinks on Linux or Unix

June 13, 2017June 13, 2017in BASH Shell, CentOS, Debian / Ubuntu, FreeBSD, Linux, Mac OS X, RedHat and Friends, Suse, Troubleshooting, UNIX last updated June 13, 2017

I recently ran a command ‘sed -i 's/CONFIG_1/CONFIG_OPT_2/g' /etc/nginx/sites-enabled/*.conf‘ on a Debian Linux server. However, the sed command destroyed the link and created a regular file in place of the link file. How can I prevent my ‘sed -i’ command from destroying symlinks on Linux or Unix-like system?

How to allow root login from one IP address with ssh public keys only

June 10, 2017in CentOS, Debian / Ubuntu, FreeBSD, Linux, Openbsd, RedHat and Friends, Suse, UNIX last updated June 10, 2017

I am using MacOS on the desktop and Ubuntu Linux on the server. I disabled root login over ssh and enabled ssh based public key login. However, I recently added second Ubuntu server. I need to sync file between two using rsync command. Is there any way that I can log from the second server into my first server with root user from second server IP address only ([email protected] }# ssh [email protected]) without reducing OpenSSH server security option?