Tips for SSH, Vim, iTerm, and more

This class is many students’ first experience working with complex projects on the command line. In this handout, I’m attempting to aggregate resources that may help you become more efficient. I use Mac OS, iTerm, and vim, and unfortunately I don’t know of too many resources for other platforms, but please make suggestions and I’ll aggregate the tools you all find helpful!

General SSH tips

Avoid SSH timeouts

If you let an SSH session sit too long without activity (sometimes even as short as a few minutes), you’ll often get connection issues:

Write Failed: broken pipe

This is easy to mitigate by adding the following to ~/.ssh/config (you may need to create this file if it doesn’t exist):

Host *
    ServerAliveInterval 60

This works on Mac and Linux. It may also apply to Windows, depending on which terminal emulator you’re using (it should apply if you’re using Ubuntu on Windows).

Avoid having to type your password every time

Note: I haven’t tested this thoroughly, so please let me know how it works. I use Kerberos with SSH to avoid having to type my password, but this was discontinued in OS X Sierra (I haven’t upgraded). I briefly tested this and it seems to work well, but I haven’t tested thoroughly.

Add this to your ~/.ssh/config, replacing yourSunetId with your Stanford username:

Host myth myth.stanford.edu
    HostName myth.stanford.edu
    User yourSunetId
    ControlMaster auto
    ControlPath ~/.ssh/%[email protected]%h:%p
    ControlPersist yes

Now, you can simply type ssh myth. The first time, it’ll ask you for your password, but if you fire up more SSH sessions after that, it log in without asking for credentials.

This works on OS X, and I believe it should work on Linux as well. If you’re using Ubuntu on Windows, you can try it, but I have no idea if it works.

Terminal emulators

iTerm2 (OS X)

https://www.iterm2.com/

iTerm is a replacement for the Terminal.app that ships with all Macs. I highly recommend it; it’s loaded with way more features than I know how to use, but also designed very well such that those features never get in your way. You can download it and start using it without knowing anything about it in particular. The features I use most often:

Vim plugins/tips

If you are new to vim, you can run vimtutor in your shell to get a minimalistic text-based tutorial on how to use the editor. Even if you know your way around, it may be worth skimming through the text; you may find something useful you didn’t know existed. OpenVim is a nice interactive tutorial, and, if memory serves me correctly, it’s how I got started with vim. Wikia has a good vim cheat sheet.

There are many more features of vim than I can list here that make it worthwhile to learn; sessions, macros, integrated make, a huge ecosystem of plugins, and many other features make it more powerful than many other editors around. I’m only listing some tips that I think offer huge time savings, but there’s a lot more to learn!

Motions

I think one of the biggest reasons people find vim painful is that it takes them so long to move around a codebase and do the most basic things. There is definitely a steep learning curve, but motions in vim are designed such that if you learn how to use them well, you’ll be faster than in any other editor.

You should get familiar with basic vim motions (h is left, j is down, k is up, l is right… You can repeat motions, e.g. 5j is “move 5 lines down”). It’s tempting to just use the arrow keys (or your mouse), but if you practice using these motions, they eventually become second nature, and are much faster than the navigation you may be used to.

Other useful motions: * ^ is “move to the start of the line,” and $ is “move to the end of the line” * b is “move to the previous word,” and w is “move to the next word” * } is “move to the next paragraph” (or the next chunk of code), and { is “move to the previous paragraph” * % means “move to the matching bracket or parentheses” (e.g. if you’re at the opening bracket of a function and want to move to the end of a function) * f allows you to jump to the next occurrence of a character, and F allows you to jump to the last occurrence of a character. (e.g. f( will move you to the next open parentheses)

Motions are so useful because they can be combined with verbs. y is the copy verb; y3j means “copy the next 3 lines,” and y} means “copy from here until the end of the paragraph.”

Relative line numbers

Relative line numbering is super useful. It makes your line numbers look like this:

If I want to delete from the current line (line 6) to the line reading set incsearch, I can look at the relative line numbering to the left, see that the desired line is 5 lines down, and hit d5j. This makes deleting/copying/selecting chunks of text so much easier.

When I switched, I found I didn’t miss absolute line numbering at all. If I needed to go to a specific line of a file, I’d just type the number in and hit gg to jump to that line (e.g. 55gg to go to line 55).

To enable this behavior, add the following to your ~/.vimrc:

set number
set relativenumber

Enable mouse interaction

I think this is now already enabled in the default .vimrc for new users at Stanford, but I’m not sure. If you add set mouse=a to your vimrc, you can click around in the editor, scroll, drag to highlight, etc… In general, it is better/faster to use a keyboard to navigate and do things, but sometimes being able to use a mouse is nice.

Add these lines to your .vimrc:

" Show search results as you type
set incsearch
" Highlight all search results
set hlsearch

You can search using the / character (e.g. type /hello to find instances of “hello” in your code). Press n to jump to the next instance of the search result and N to jump to the previous instance.

Split screening

Being able to see multiple files at the same time is super, super useful in this class!

For easy split navigation, add this to your .vimrc:

nnoremap <C-J> <C-W><C-J>
nnoremap <C-K> <C-W><C-K>
nnoremap <C-L> <C-W><C-L>
nnoremap <C-H> <C-W><C-H>
set splitbelow
set splitright

Now, to split the screen horizontally (i.e. to have two panes, one above each other), in command mode, type :sp (for “split”). To split the screen vertically (i.e. to have two panes side by side), type :vsp. To move up (assuming you have the above nnoremaps in your config), press ctrl+k; to move down, press ctrl+j; to move left, press ctrl+h; and to move right, press ctrl+l.

Once you are in a split pane, you can load a file using :e filename, or using FZF (see below).

More on splits: * https://robots.thoughtbot.com/vim-splits-move-faster-and-more-naturally * http://vimcasts.org/episodes/working-with-windows/ (video)

Marks

Sometimes, you’re working on some portion of code, and you want to briefly glance up at some other part of a file before returning to where you’re working. You can set a mark where you’re currently working by typing ma (mark a), then scroll up to wherever you want to go, and then jump back down to where you were before by typing 'a (go back to mark a). You can set multiple marks if you want (e.g. mb will set mark b), but I generally can only keep track of one in my head…

Vundle

The following tips involve vim plugins. Vundle is a plugin manager to make installing things easy. To install Vundle, run the following:

git clone https://github.com/VundleVim/Vundle.vim.git ~/.vim/bundle/Vundle.vim

Then, add the following towards the top of your .vimrc (if any of the following lines are already in your vimrc, you can omit them):

set nocompatible              " be iMproved, required
filetype off                  " required

" set the runtime path to include Vundle and initialize
set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()

" let Vundle manage Vundle, required
Plugin 'VundleVim/Vundle.vim'

" Keep Plugin commands between vundle#begin/end.

" ---------- ADD Plugin DECLARATIONS HERE ---------

" All of your Plugins must be added before the following line
call vundle#end()            " required
filetype plugin indent on    " required

My tips below mention Plugin declarations. Add those lines where indicated at the dashed line above. Every time you add a new plugin to your .vimrc, save the .vimrc file and then run :PluginInstall to install the new plugin.

YouCompleteMe (autocomplete)

YouCompleteMe is a pretty sophisticated autocomplete plugin that makes vim more like an IDE. To install, add this to your .vimrc (see notes on Vundle above):

Plugin 'Valloric/YouCompleteMe'

After running :PluginInstall, run this in your shell:

cd ~/.vim/bundle/YouCompleteMe
./install.py --clang-completer

fzf (Fuzzy file finder)

fzf is an excellent plugin for quickly navigating to files without closing vim. You may see me do this in lecture; I press my spacebar twice, enter a few characters that are part of the filename I want, then select the desired file, and voila, it’s open!

It has been a long time since I installed this, and I’m forgetting some details. Try these instructions and please let me know if you run into problems on myth.

Run this in your shell:

git clone --depth 1 https://github.com/junegunn/fzf.git ~/.fzf
~/.fzf/install

Then add this to your .vimrc (see Vundle instructions above):

set rtp+=~/.fzf
Plugin 'junegunn/fzf'
Plugin 'junegunn/fzf.vim'
" This is the default extra key bindings
let g:fzf_action = {
  \ 'ctrl-t': 'tab split',
  \ 'ctrl-x': 'split',
  \ 'ctrl-v': 'vsplit' }

" Default fzf layout
" - down / up / left / right
let g:fzf_layout = { 'down': '~40%' }

" space space to open fzf file finder
let mapleader = "\<Space>"
nnoremap <silent> <leader><space> :Files<CR>

" Enable hidden buffers (don't need to save when switching files)
set hidden

Press “space space” to open fzf. To open a file, hit enter. To split the screen vertically and open the file in the new split pane, press ctrl+v; to split horizontally, press ctrl+x.

ag (Silver Searcher)

ag lets you quickly find files containing a search term. Need to know where the inode struct is defined? Just type :Ag struct inode { and you can easily open ino.h from there.

Again, it has been years since I installed this, and the installation instructions have since changed, so let me know if you run into problems.

You’ll need to install ag first; on Mac, this is just brew install the_silver_searcher, but check the linked README for instructions on other platforms. Then, add this to your .vimrc:

Plugin 'mileszs/ack.vim'
let g:ackprg = 'ag --vimgrep --smart-case'
cnoreabbrev ag Ack
cnoreabbrev aG Ack
cnoreabbrev Ag Ack
cnoreabbrev AG Ack

Airline

This is a really great plugin for formatting the vim display. I have it showing my currently-open files at the top of the screen, and I can press “space 3” to switch to the 3rd “tab.” I need to run to lecture now, but I’ll post some more details after class…..

Plugin 'vim-airline/vim-airline'
let g:airline#extensions#tabline#enabled = 1
"set airline 
let g:airline#extensions#tabline#tab_nr_type = 1 " tab number
let g:airline#extensions#tabline#show_tab_nr = 1
let g:airline#extensions#tabline#formatter = 'default'
let g:airline#extensions#tabline#buffer_nr_show = 1
let g:airline#extensions#tabline#fnametruncate = 20
let g:airline#extensions#tabline#fnamecollapse = 2
let g:airline#extensions#tabline#buffer_idx_mode = 1

nmap <leader>1 <Plug>AirlineSelectTab1
nmap <leader>2 <Plug>AirlineSelectTab2
nmap <leader>3 <Plug>AirlineSelectTab3
nmap <leader>4 <Plug>AirlineSelectTab4
nmap <leader>5 <Plug>AirlineSelectTab5
nmap <leader>6 <Plug>AirlineSelectTab6
nmap <leader>7 <Plug>AirlineSelectTab7
nmap <leader>8 <Plug>AirlineSelectTab8
nmap <leader>9 <Plug>AirlineSelectTab9

Emacs plugins/tips

Sadly, I know so little about emacs that I’m not sure I even know how to save a file. Please send me recommendations, and I’ll post them here!

Other fun things