Opening tab in Terminal resizes window
While this is not a full solution but more of a workaround, I still thought it's worth sharing.
Like many on this thread, I noticed that, much to my annoyance, the Terminal window changes size when I add new Tab on El Capitan (10.11.3). I'm also using Spectacle for arranging my windows from the keyboard. I thought it might be an issue with spectacle but the same happens when I quit spectacle and resize Terminal windows with touchpad.
From what I noticed it only happens to me when when the below sequence is followed: 1. Open a new Terminal window 2. Add a new tab 3. Make the window smaller (height or width) 4. Add a new tab, and this one will change the size of the window.
Nothing happens when I make it bigger. I figured through experimentation that each and every tab in the window must be holding it's dimensions form when it was last viewed. In this particular scenario the last new tab in step 4 will change the size of the window to what it was when tab 1 was last viewed.
Now this is most important bit. The new tabs will adjust its dimensions to the biggest tab in the window.
Workaround: When I resize the Terminal window, I use Shift+CMD+Arrows to quickly browse through all the tab in this window. If I do that, new tabs will not affect the size of the window.
While it might be useful to some, I understand that it is not really practical, especially if you have a lot of tabs open. It is my way of dealing with this until a proper solution comes along.
This behavior is due to the Window settings in Terminal. All new terminals open to what is specified under Window (default is 80 x 24). When you open a tab, it resizes the window to the new tab.
I wasn't able to find a solution to this for Terminal.app, however, I've since switched to iTerm 2, and it doesn't suffer from this issue. All new tabs open to the same dimensions as the existing window they're opened into, rather than resizing the window to the default.
You can find iTerm 2 at http://www.iterm2.com/
Open Terminal
Click on Terminal on the menubar, go to Preferences
Select General
Change the option 'New tabs open with' to 'Same Profile'
Resize your Terminal in Mac Preferences to fit your needs:
Open Terminal with Spotlight (⌘space, enter 'Terminal') and open Preferences (⌘,). In the Window tab, look at the Window Size, Columns & Rows. The values are often 80 and 24.
Optionally, resize your window to fix your desired new size. Pause and think, 24 lines, how wide is a line? OK, how many do I need?
Increase column size if when you both create a new tab or new window it is not the same size as your desired size.
Trial and error, just attempt to keep your estimates close and it will be brief. Similarly decrease if it is too large, for example, on this 1920 × 1200 scaled display the following is great for me: 130 & 40
Test your new setting by opening a new tab (⌘T).
Place your window over the previous one, is it the same size or close enough for you? If not keep resizing, until it is.
Open a new terminal window also (⌘N) and do similar.
Now consider using a window management program, I recommend Spectacle because it is free as in free beer and freedom: https://github.com/eczarny/spectacle
You can then use the following to move windows quickly while a window is selected: ⌘⌃→
This places the window in the top right corner 1/4 of the screen, left works similarly. If you also hold down shift it will place the window below in the 1/4 half of the screen: ⌘⌃⇧→
Plenty more options are available, enjoy!