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

Posted on in Categories , , , , , , , , , 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?

Ansible: Could not find aptitude. Please ensure it is installed Error and Solution

Posted on in Categories , , , last updated June 13, 2017

I am running the ‘ansible-playbook -i hostnames upgrade.yml‘ command but getting an error that read as follows

fatal: [db1]: FAILED! => {“changed”: false, “failed”: true, “msg”: “Could not find aptitude. Please ensure it is installed.“}

My yml file includes the following line:

- apt: update_cache=yes upgrade=yes

How do I fix this error on a Debian or Ubuntu Linux server?

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

Posted on in Categories , , , , , , , 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?

How to install tinc VPN on Ubuntu Linux 16.04 to secure traffic

Posted on in Categories , , , last updated June 27, 2017

I have two VPS running in the cloud. The first one is the database, and another one is the web server. I want to secure traffic that flows between private network which is insecure by design and I do not want to use OpenVPN due to complex settings. How do I install and setup tinc VPN server and secure my traffic over VPN on Ubuntu Linux 16.04 LTS server?

How to extract multiple tar ball (*.tar.gz) files in directory on Linux or Unix

Posted on in Categories , , , , , , , last updated May 30, 2017

I have tried tar -xvf *.tar.gz command, but getting an error that read as:
tar (child): *.gz: Cannot open: No such file or directory
tar (child): Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error is not recoverable: exiting now

How can I extract multiple *.tar.gz files in directory using Linux or Unix-shell prompt?