ssh-agent

ssh-agent is a background key manager that stores your decrypted SSH private keys in memory and signs authentication challenges on your behalf (via a Unix domain socket, see below for more detail on this), allowing passwordless SSH logins without exposing the keys themselves.

You can check if ssh-agent is running:

A) In Windows (PowerShell)

Get-Service ssh-agent

B) In Windows (Cmd.exe)

sc query ssh-agent

In both cases, if the agent is stopped you can start the agent.

C) In Linux

ps -ef | grep ssh-agent

ssh-agent does not use TCP (or other network-related ports) for communication. Instead it uses via a Unix domain-socket (local socket for IPC) specified by the SSH_AGENT_SOCK environment variable.

Technical note: SC (typed as sc in regular usage in CMD.EXE) is a command line program used for communicating with the Service Control Manager and services.  SC query - queries the status of a service, or enumerates the status for types of services.

Various Python Text UI Options

We have covered Textual in an earlier post.  Some other frameworks to build text UIs in Python include:

• Curses - a wrapper around Unix ncurses
• Rich - rich text formatting in the terminal

TCPL Still Rules the Linux Roost

The programming language C (born in the 1970s, created by Dennis Ritchie, who also created its predecessor, B) still rules the roost as far as the Linux kernel is concerned, whereby of 37 million lines of code, we have just over 35m LOCs written in C as per analysis from OpenHub.

Linux is the open source version of Unix, which was written in C, and prior to that in assembler. The introduction of the programming language C made the code portable to different hardwares.

Ken Thompson and Dennis Ritchie and their colleagues at Bell Labs (AT&T) were the co-creators of the Unix Operating System, created in 1969.   Douglas McIlroy introduced the Unix philosophy of small, composable tools. Brian Kernighan helped to popularise UNIX and C through co-authoring The C Programming Language with Dennis Ritchie.