$PATH, /bin and $PS1

In this talk, Kim demystifies the $PATH variable, which is often a part of installing new dev tools, she will describe how your computer stores executable files in your /bin directory, and the Filesystem Hierarchy Standard that governs the root directory, and she’ll show you how to customize your command line by altering the $PS1 variable.

This talk is for people who use a terminal to run commands and want to learn more about what’s going on and how to customize their command-line interface.

There is a companion blog post to this talk at https://kimschlesinger.com/2020/02/25/PATH-FHS-PS1/

Transcript

1. @kimschles $PATH, /bin and $PS1 Kim Schlesinger DenverScript, February 2020
2. @kimschles Has this ever happened to you?
3. @kimschles Source: Installing node.js on macOS Mojave, macOS Sierra and earlier OSX
4. @kimschles “make sure that /usr/local/bin is in your path..”
5. @kimschles Add it to your PATH
6. @kimschles
7. @kimschles $PATH, /bin and $PS1
8. @kimschles Hi, I’m Kim
9. @kimschles *nix
10. @kimschles
11. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
12. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
13. @kimschles Environment Variables • Key value pairs that your system can access and use • ALL_UPPERCASE Commands: • env • echo $ENV_VAR
14. @kimschles Shell “A shell reads your commands and tells the OS to do things.” -- Julia Evans Source: https://twitter.com/b0rk/status/1218647766097940481
15. @kimschles
16. @kimschles
17. @kimschles echo $shell
18. @kimschles Bourne Shell /bin/sh
19. @kimschles Born Again Shell AKA BASH /bin/bash
20. @kimschles zsh /bin/zsh
21. @kimschles
22. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
23. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
24. @kimschles echo $PATH
25. @kimschles
26. @kimschles /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
27. @kimschles /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin • Environment Variable • 1 long string • Colon-separated • Is a path to executable code invoked through text commands
28. @kimschles /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin /usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /sbin /bin
29. @kimschles Permanently Edit PATH • Update PATH in .bashrc, .bash_profile or .zshrc file • /usr/local/go/bin export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
30. @kimschles Permanently Edit PATH • Update PATH in .bashrc or .bash_profile file • /usr/local/go/bin export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/go/bin
31. @kimschles Temporarily Edit PATH • From the command line. Only lasts in current shell. PATH=$PATH:/usr/local/go/bin
32. @kimschles Where did it go? which node
33. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
34. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
35. @kimschles /bin • bin stands for binary, which is a file you can execute • A collection of scripts • /bin has the basic commands we use like cat, mkdir, echo, pwd, rm
36. @kimschles ~ Home Directory / Root Directory
37. @kimschles ls /
38. @kimschles Source: https://en.wikipedia.org/wiki/Unix_filesystem#/media/File:Standard-unix-filesystem-hierarchy.svg
39. @kimschles “The Filesystem Hierarchy Standard (FHS) defines the directory structure and directory contents in Linux distributions. It is maintained by the Linux Foundation. The latest version is 3.0, released on 3 June 2015.” Source: https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
40. @kimschles /bin /sbin /dev /etc /tmp /usr
41. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
42. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
43. @kimschles
44. @kimschles echo $PS1
45. @kimschles PS1 • An environment variable • Creates the default command prompt you see at the beginning of your command line.
46. @kimschles \u@\h:\w\$
47. @kimschles \u@\h:\w\$ \u = username \h = hostname \w = working directory Separated with @, : and $
48. @kimschles \u@\h:\w\$ kschlesinger@kims-macbook-air:~$
49. @kimschles Add colors (and emojis) Open you .bash_profile, .bashrc or .zshrc file and Add ANSI color escape sequences before each section of your PS1. Add emojis if you’d like.
50. @kimschles export PS1="\[\033[36m\]\u\[\033[m\]@\[\033[32m\]\h: \[\033[33;1m\]\w\[\033[m\]\$ "
51. @kimschles Agenda 1. Key Terms 2. $PATH 3. /bin 4. $PS1
52. @kimschles Recap
53. @kimschles $PATH
54. @kimschles /bin and the Filesystem Hierarchy Standard
55. @kimschles $PS1
56. @kimschles $PATH Resources I’ve learned alot about the PATH variable from Breanne Boland, who wrote the first two articles on this list. • Access & Make Awesome Your PATH System Variable • When laziness is efficient: Make the most of your command line • PATH Definition • How to Modify the Shell Path in macOS Sierra and OSX using Terminal • What is the difference between .bash_profile and .bashrc?
57. @kimschles /bin and FHS Resources • Filesystem Hierarchy Standard • Wikipedia: Filesystem Hierarchy Standard • The /bin Directory • Linux Directory Structure explained: /bin folder
58. @kimschles $PS1 Resources • How to Customize Shell Variable PS1-PS4 on Bash Prompt • UNIX StackExchange: Colorizing your terminal and shell environment • My Mac OSX Bash Profile • StackOverflow: List of ANSI color escape sequences • Simple Tricks to Improve the Terminal Appearance in Mac OS X • Customize the colors of your Terminal in Mac OS X
59. @kimschles Blog post with links: https://kimschlesinger.com/2020/02/25/PATH-FHS-PS1/
60. @kimschles kimschlesinger.com developdenver.org