CLI for Artists + Designers

Command-Line Interface (CLI) is a great way to perform common tasks involving digital media (converting, cropping, downloading, merging, ...) without the need for a graphical user interface (GUI). These tools are open-source (free) and written to perform single tasks really well. Once you install the following tools, you'll be surprised how rarely you need some big software programs for many of your image/movie/sound tasks.

Workflow: Once setting the working directory/folder to use, you write single line commands, which start with the name of the tool to use, followed by parameters that set the input file, options and output destination. All commands are followed by the ENTER key to run.

This guide is written for MacOS, where the built-in CLI tool is known as Terminal, sitting in your Utilities folder.

TOC

• CLI Basics - command-line intro
• Homebrew - package manager
• Imagemagick - images
• FFmpeg - movies
• youtube-dl - download media

CLI Basics

There's just a few commands/tips you really need to know at first.

note: directory means folder

• cd (change directory), used to set working dir for accessing files.

• ../ (parent folder), used w/ cd to navigate one directory up.

• ls (list), lists all files within working dir.

• UP ARROW (history), toggle through previous commands.

• TAB autocomplete commands / directory names

• say hello world (text-to-speech), never gets old...

• man (manual), used before name of tool, to learn about its options.

• pwd prints the name of the working directory

• touch followed by a filename + extension creates an empty file of that kind

  touch index.html # creates an empty file called index.html

• mkdir followed by a name, creates an empty directory

  mkdir new_directory # creates empty folder
  cd new_directory # change to my_folder 
  touch index.html # creates an empty file called index.html
  touch style.css # creates an empty file called style.css
  mkdir js # creates an empty directory called js
  touch js/script.js # creates an empty script.js file inside the js directory
  
  new_directory
  ├── js
  │   └── script.js
  ├── index.html
  └── style.css

• python -m SimpleHTTPServer 8000 creates a server on port 8000 localhost:8000 it is possible to set any available port number

Set active directory

You always set the folder you're working in, either for processing files in that folder or having items download to that directory.

cd path/to/directory

The easiest way to do this is just type cd + spacebar, then drag and drop the folder into the Terminal window. Hit Enter and you're now working in that folder. You can test by listing the contents with ls.

Careful

Use caution if following guides with the following commands

• rm + rmdir (remove + remove directory), permanently removes files!
• sudo (root), sometimes needed for system changes, but gives admin privledges.

Homebrew

Homebrew is a package manager.
They keep an updated list of tools and make their installation super easy.

Install

copy + paste into the following into Terminal:

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

It will inform you what it needs to install, ask you to press ENTER to continue, then request your computer's password (only time it should be needed). FYI: you won't see your password while typing, just press ENTER when done.

Usage

After it's installed, to install any package, you just enter:

brew install packagename

Imagemagick

Imagemagick is for images.
Amazing at batch processing to a directory of images.

Install

brew install imagemagik

Usage

Once installed, you call it (on MacOS) with convert,
then pass any number of input and output arguments.

GIF from directory

Navigate to folder of images, as described above in Set active directory.

Grab all *.png or *.jpg and output GIF

convert *.png -loop 0 test.gif

• convert launches Imagemagick
• *.png grabs for all pngs
• -loop 0 sets infinite looping
• test.gif name of output file (customize).

Resize in batch

Navigate to folder of images, as described above in Set active directory.

Create folder for output using mkdir (make directory)

mkdir thumbs

Batch process using mogrify, »

mogrify -resize 128x128 -quality 100 -path ./thumbs *.jpg

• mogrify launch batch tool of Imagemagick,
• -resize #x# resizes (can also use percentages)
• -quality 100 sets compression
• -path ./thumbs specifies where to put outputs
• *.jpg specifies fileformat of output.

Additional Links

• Imagemagick CLI
• Mogrify Guide

FFmpeg

FFmpeg is for movies.
It's the underlying tech beneath most online/offline media converters.

Install

brew install ffmpeg

Usage

Once installed, call with ffmpeg, pass -i input file, options, output file.

ffmpeg -i myfile.mov myfile.mp4

Convert format

It's really as easy as above! You don't even need to set an active directly, you can also just type ffmpeg -i then drag + drop original file, drag + drop again, replace suffix with new filetype.

ffmpeg -i input_file output_file.filetype

Trim

Super useful to extract moment from movie

ffmpeg -ss 10 -i input.mp4 -c copy -t 15 output.mp4

• ffmpeg launches FFmpeg
• -ss ## sets starting point in sec
• -i input.mp4 sets input file
• -c copy creates new file, instead of modifying original
• -t ## duration for new clip in sec (use -to ## for time in clip)
• output.mp4 name/path for new output file

Export frames

Want to build a contact sheet of frames per every second?

Navigate to folder of images, as described above in Set active directory.

Create folder for output using mkdir (make directory)

mkdir out

Set input file, frames per second for output, file path/type

ffmpeg -i input.mp4 -vf fps=1 out/out%03d.png

• -vf fps=1 exports # frames per second

Speed

Useful to speed up long screen-recordings.

ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" output.mp4

• -filter:v "setpts=0.5*PTS" 0.5 = 50% speed, 1.0 = normal, 1.5 = 150%

Additional Links

• FFmpeg CLI guide
• Werner Robitza FFmpeg guide
• 20 FFmpeg commands for beginners

youtube-dl

youtube-dl is an online media extractor.
The ultimate tool for downloading and preserving media files from any website.

Install

brew install youtube-dl

Usage

cd the directory for saving file to, then as simple as

youtube-dl VIDEO_URL

Formats

Most hosted videos have multiple files to stream depending on connection speed.

List formats

youtube-dl VIDEO_URL -F

It will return a long list of available formats, starting with an ID.
Then download the one you prefer

youtube-dl VIDEO_URL -f ##

Or download the best mp4 or similar format

youtube-dl -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best' VIDEO_URL

Or download the best m4a or audio format

youtube-dl -f 'bestaudio[ext=m4a]' VIDEO_URL

Additional Links

• youtube-dl options

And Then...

This is just a short guide for helping our design students do things faster with less interface! Am I missing any crucial tools or tips? Let me know as an issue or make a pull request on GitHub.

cc teddavis.org 2019