Setup

This chapter covers terminal navigation, file manipulation, pipelines, and process control. All of these work identically on any Unix-like system.

Environment tier: any — macOS, Linux, or Windows via WSL all work for everything in this chapter.

Windows

Install WSL 2^[1]. Open the Microsoft Store, search for Ubuntu^[2], and install it. Once installed, open the Ubuntu app. The prompt that appears is a Linux Bash shell running inside a real Linux kernel. Every command in this chapter runs there without modification.

macOS

Terminal.app or iTerm2 work for this chapter. macOS defaults to zsh, but Bash is still installed at /bin/bash. Most commands in f01 are identical in either shell — but the environment and shell scripting pages use ~/.bashrc and #!/bin/bash, which are Bash-specific.

The simplest path: open your terminal and run bash. You are now in a Bash session and everything in this chapter works as written.

If you prefer to stay in zsh, use ~/.zshrc instead of ~/.bashrc and #!/bin/zsh in your shebangs. The concepts are identical; only the file names differ.

One note: later chapters (from f04 onward) require Linux-specific features that do not work on macOS natively. From f04 onward, this chapter's approach no longer applies — some chapters require GCC, Linux syscalls, or platform-specific toolchains that diverge on macOS (Darwin). The easiest path forward on Mac is a Linux VM via UTM^[3] with Ubuntu. You do not need to set that up now.

The final page of this chapter installs NetHack. On macOS: brew install nethack if you have Homebrew, or use your Linux VM — which is a good excuse to set it up before f04.

Linux

Open a terminal. You are already there.

Verify

Run these two commands:

echo $SHELL
uname -s

echo $SHELL prints your shell path — something like /bin/bash or /usr/bin/zsh. uname -s prints the kernel name. On Linux (including WSL) it prints Linux. On macOS it prints Darwin. Either is acceptable for this chapter.

If uname -s prints Linux, you are ready for every chapter in the curriculum. If it prints Darwin, you are ready for f01 and f02 — set up a Linux VM before you reach f04.

Compatibility notes

sed -i

sed -i works differently on GNU sed (Linux, WSL) and BSD sed (macOS):

# GNU sed — Linux and WSL
sed -i 's/old/new/' file
 
# BSD sed — macOS
sed -i '' 's/old/new/' file