Section 1.1: The 'cat' Command

Let's kick things off with a straightforward command: "cat". This command is used to display the contents of text files and is one of the oldest in Unix, dating back to Unix Version 1 in 1973.

What astonished me is not just that this command has remained unchanged over the past 50 years, but also that the "/etc/passwd" file is still in the same directory. Interestingly, even earlier versions, like Unix Version 0, utilized "cat" with teletype and paper outputs.

To further explore its historical context, check out this video demonstrating Unix version 0:

Section 1.2: The 'cc' Command

Next, we have the "cc" command, which invokes the C compiler. Although it may not qualify as a typical OS command, it’s crucial to mention since the C programming language was introduced in 1972 and remains widely utilized today, particularly in microcontrollers and low-power devices.

Let’s write a simple "Hello World" program using the K&R C syntax from the 70s:

#include <stdio.h>

main() {

printf("Hello, worldn");

}

While the syntax may appear outdated—lacking the 'void' declaration and a return value for 'main'—this code can still be compiled successfully in both legacy and modern systems.

Section 1.3: The 'cron' Job Scheduler

System administrators are likely familiar with Cron, a Unix job scheduler that first emerged in 1975. This tool makes it easy to automate tasks, such as scheduling a daily reboot of the system.

As expected, the command syntax remains consistent from its inception to present.

Section 1.4: The 'ed' Text Editor

"Ed" is perhaps the oldest text editor available in Unix, introduced in 1973. It operates in command mode, where you must press the "a" key to enter text, and use the "." symbol to conclude editing.

This line-oriented editor may seem alien today, but it was designed for a time when text was printed on paper using teletypes.

Section 1.5: The 'ifconfig' Command

The "ifconfig" command is still relevant for retrieving network interface parameters, such as netmask or IP address. Released in 1983, its logic remains intact despite changes in technology.

Section 1.6: Mounting Drives

The "mount" command allows you to connect devices, like a USB drive, to a Raspberry Pi. The core commands such as "df" to list drives and "mkdir" to create directories have been in use since 1979.

Modern systems can mount USB drives, a significant advancement from the massive drives of the past, like the Digital RP03, which weighed 140 kg.

Section 1.7: The 'tar' Command

Most users are familiar with "tar" files, a term that originally stood for "Tape Archive". This command debuted in 1979, allowing users to consolidate multiple files into one archive.

Today’s tape drives, such as the LTO series, still utilize the TAR command for archiving, showcasing its lasting significance.