Useful Terminal Commands (OS X)

Mac OS X guide Tue 21 August, 2018

Get to know the built-in terminal on your Mac

The Terminal is a powerful command line interface on Mac OS X. Terminal can perform simple tasks like navigating and editing files, but can also be used to monitor your network or computer, access a remote server and configure hidden settings.

All of the terminal commands listed here are perfectly safe to use. Any preference changes are completely reversible. That being said, Terminal does what you tell it to, so be careful what you wish for…

Basically, when typing commands, especially after entering sudo, ensure they are typed correctly to avoid any unwanted changes.

Using sudo means we are requesting to run as a superuser. It can generally be understood as “superuser do.” By default, sudo requires entering our Mac’s login password.

(Remember: You won’t see the cursor move when typing your password in terminal.)

Our list of useful Terminal commands

Change default screenshot directory on OS X

By default, any screenshots you take on your Mac will save to your desktop. If you’d like to change that to a custom directory like /Documents/Screenshots, then you can do that quite easily with the following steps

1. Open “Terminal” Application, found in /Applications/Utilities and enter the following command

defaults write com.apple.screencapture location

2. Now enter a space after “location” and drag the folder you created over to Terminal (which will insert the file path of the folder), or enter the location yourself.
3. Hit Enter on your keyboard, then type in:

$ killall SystemUIServer

4. Press Enter again and you’re done.

Download Youtube Videos and Extract Mp3 file.

To do this you will need youtube-dl, which is a command line program that allows you to download videos from YouTube. For further information, view the youtube-dl documentation. You can install youtube-dl with Homebrew by running the following command. (If you haven’t used this before, check our 30 second guide to install homebrew.)

 $ brew install youtube-dl

Hit enter and let it install. Downloading a video is very simple. All you need to do is give youtube-dl a URL and it will do the rest.

$ youtube-dl https://youtu.be/Agl1TgVfls0

To download the mp3 directly from youtube without using FFMPEG

$ youtube-dl --extract-audio --audio-format mp3 [Vid URL]

Monitor your network with Iftop

Iftop is a system monitor tool that produces a list of network connections. It displays a table of current bandwidth usage.

(If you have homebrew installed skip to step 3)
1. Press Command+Space and type Terminal and press enter/return key.
2. Run in Terminal app:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" < /dev/null 2> /dev/null

and press enter/return key.

If the screen prompts you to enter a password, please enter your Mac’s user password to continue. When you type the password, it won’t be displayed on screen, but the system will accept it. So just type your password and press ENTER/RETURN key. Then wait for the command to finish.

3. Run:

brew install iftop

When that’s installed you’re done.

4.You can now use

iftop.

Monitor system activities with htop

Htop is an interactive process-viewer and process-manager. It is an alternative to the Unix program top (which comes pre-installed on Mac).

It shows a frequently updates list of processes running on the computer, which will usually be ordered by the amount of CPU Usage. Htop uses colour and gives visual information about processor, swap and memory status.

1. You’ll need Homebrew installed, you probably know what that is and how to do that by now though, so proceed to the next step.
2. Install Xcode from the Mac App Store. (Performing any system updates can resolve issues at this stage)
3. Install htop using Homebrew

$ brew install htop

4. Run the following in a terminal window to view system activity

$ htop

Prevent your Mac from going to sleep

Ever needed to leave your Mac on to do something and it went to sleep? Prevent this with a simple command.

$ caffeinate

Entering the command on its own will keep the Mac awake until you terminate it by pressing Ctrl+C or closing the terminal window.
Add a time parameter by entering the following

$ caffeinate -u -t 1200

The 1200 represents the number of seconds, so our above command will stop the Mac from going to sleep in the next twenty minutes.

View the weather forecast in terminal

Since we aren’t using windows, you’ll probably want access to a weather application. To get the data we need to use curl.

1. Install Curl using Homebrew

$ brew install curl

2. Run the following command

$ curl wttr.in/london

I’m using the example ‘London’ as a city name but you can edit that to anywhere else.

Add a personalised message to your Mac’s lock screen

Open “Terminal” Application, found in /Applications/Utilities and enter the following command with your own custom message:

sudo defaults write /Library/Preferences/com.apple.loginwindow LoginwindowText “If lost please call (+44)7777-777-777”

Next time you go to the lock screen you will see your new message.

Command Description
sftp Establishes an sftp connection to a remote system.
bye Quits the SFTP session
help Lists all SFTP commands
ls Lists the contents of the remote working directory.
lls Lists the contents of the local working directory.
cd Changes the remote working directory.
lcd Changes the remote working directory.
mkdir Creates a directory on the remote system.
rmdir Deletes a directory on the remote system.
get Copies a file from the remote working directory to the local working directory.
put Copies a file from the local working directory to the remote working directory.
delete Deletes a file from the remote working directory.

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