How to fix: MacOS keep asking passphrase for ssh key after upgrade or reboots

I recently upgraded my MacOS Sierra and now ssh command keep asking for passphrase as follows when I try to login to my remote Linux/Unix server: Enter passphrase for key ‘/Users/vivek/.ssh/id_ed25519’: How do I fix…

How to find all hard links in a directory on Linux

I have a file named /etc/passwd i and I would like to find all hard links to this file in a directory. How do I find out all other hard links to the /etc/passwd in…

Windows like Ctrl + Alt + Delete on MacOS App To Kill Tasks

O n Windows, I can hit Ctrl + Alt + Delete and kill apps or do other stuff. Sometimes Firefox browser hangs on macOS. Is there an equivalent of Ctrl + Alt + Delete keyboard…

How to login with root password when using Ansible tool

I need to run a Linux command over 20 servers using a root user and password in Ansible too. How do I pass a user and password in Ansible over ssh based session? How can…

Google Chrome: Clear or flush the DNS cache

I think Google has its own dns caching system. I am getting the same old dns entry in my Google Chrome browser on both Linux and Apple OS X. How do I flush or clear…

How to upload ssh public key to as authorized_key using Ansible

H ow do I use Ansible to upload ssh public key to as authorized_key to multiple Linux or Unix servers saved in an inventory file?   To add or remove SSH authorized keys for particular…

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

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…

How to write Raspbian Jessie image file to SD cards on Apple macOS / OS X

I got a Raspberry PI 3 from my friend. I am a long term macOS user. How do I write Raspbian image file to SD card using macOS?   Raspberry PI 3 is a small…

How to check and verify md5/sha1/sha256 checksums for Apple MacOS X when I download files

M alware is becoming more and more common for macOS. I wanted to make sure file I downloaded files such as an ISO image or firmware are safe before install on my system. How do…

How to find disk I/O latency with ioping monitoring tool on Linux

H ow do I monitor disk I/O latency in real time on Linux, FreeBSD, OpenBSD, and MacOS operating system?   You can use ioping tool to monitor I/O latency in real time. It shows disk…