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Lecture 3

The command line

CLI

Command line interface

Terminals

Windows
macOS/Linux
- Terminal

We'll be using:

Windows: Git BASH
macOS: Terminal

Open it up.

Distributions

UNIX
UNIX-like
POSIX standard

Examples

Darwin (macOS)
Debian
Ubuntu
Mint
Fedora
Red Hat Enterprise Linux (RHEL)

Paths

Separators:
- Windows (outside of Git BASH): \
- macOS/Linux: /
. - current directory
.. - parent directory
Absolute vs. relative

Navigation

pwd - path of working directory
ls - list files
- ls -al - list all files (with dotfiles) with more details
cd - change directory
Mac:
1. From Finder, right-click on folder
2. Click Services
3. Click New Terminal at Folder

Control-r allows you to search your command history

Working with files

Viewing
- cat
- less
mv
cp
mkdir
rmdir
find
Editing
- nano
- vim

If files have spaces or special characters, need to put quotes around them.

Best to avoid these when naming files, sticking to:
- Letters
- Numbers
- Periods
- Hyphens
- Underscores
For Python files, snake case is most common.

Exiting/quitting

less: q
nano: control-x
vim: escape, then :q!
Other command line tools: control-c

Worst case, close your Terminal, and that will kill whatever process was running.

Other shell stuff

echo
- echo abc | less
Exit codes
- echo $?
Environment variables
which
- which jupyter
- which -a python3
$PATH
Pipes
- ls | xargs cat
Redirecting output
grep
sudo
- Important coder cultural reference
man

Example

Uses a "wildcard":

find . -name 'lecture_*.md'
find . -name 'lecture_*.md' | sed -E 's/([0-9]{2})/0\1/'

Shells

PowerShell
Bash
zsh

Dependency/package management

Done through package managers

Python

conda
- Anaconda channel, maintained by the company
- conda-forge, maintained by the community
pip
- PyPI
Virtual environment

Operating system

Linux: Aptitude, Snapcraft, others
- Debian packages vs. Snaps
Mac: Homebrew
Windows: Windows Package Manager / WinGet, Chocolatey

Project Part 2

Note to self: Send terminal commands+output.