Learn from an experimental physicist

Sep 01, 2016 learning text editor phys-492/592

When you log into a Linux machine using PuTTY from a Windows PC, you need a terminal based text editor to create or modify text files. If all you want to do is to read a text file, you need the following commands instead of a text editor:

$ cat README.txt # dump contents of README.txt to terminal
$ head -6 README.txt # dump the first 6 lines of README.txt to terminal
$ tail -7 README.txt # dump the last 7 lines of README.txt to terminal
$ less README.txt # use the whole terminal to show README.txt

less will occupy the whole terminal window to show the contents of a file. It is very useful for reading a file that is much longer than what can be shown in a small terminal window. You can use space to move down 1 page, and b to move up 1 page. For finer scrolling, press j to scroll down only one line, k to scroll up one line. You can search a word by pressing / first and then typing in the word you want to search for. If there are multiple occurrences of the word, you can used n to jump to the next occurrence, and p to jump to the previous occurrence. If you are done with browsing, press q to quit less and go back to the command prompt. If you want to change something in the file, press v to open it using the default text editor.

The default text editor is set through an environment variable using the following command:

export VISUAL='yourFavoriteTextEditor'
# or
export EDITOR='yourFavoriteTextEditor'

Save the setting to your .bashrc if you want to use this setting for later ssh sessions.

If none of the environment variable ($VISUAL or $EDITOR) is set, less will use vi to edit the file. Vi is one of the oldest and most popular text editors together with Emacs. Vi is quite unique in its way to handle keyboard shortcuts. Unlike most other editors, where shortcuts are combinations of modifier keys and other keys, for example, Ctrl+c is a shortcut of copy and Ctrl+v is a shortcut of paste, in Vi you have to switch to a special state, called Command mode, where normal keys can be pressed directly to issue commands without the need to hold a modifier key at the same time, for example, yw copies a word, p pastes the word. Normal keys behave normally only in the Insert mode. Such a concept is quite counter intuitive, or more precisely, quite different from the editing habit most people have established from their daily usage of Windows. According to a study, it takes beginners much more time to learn Vi than to learn Emacs, while experienced Vi and Emacs users are equally efficient. Given such a result, a regular Windows user who wants to learn Linux command line operation should avoid learning Vi to save time.

Many terminal based editors have emerged after Vi and Emacs. They normally have keyboard shortcuts that most people have got used to. It is much easier to learn them than to learn both Vi and Emacs. They may not be as powerful, but should be good enough for most casual editing. micro is one of them. Since it is meant to be a successor to the nano editor, which is small and easy to use already, micro strives to be even easier to use and intuitive. Two important editing functions that are missing from both are

  1. word completion, that is, to press a key, normally Tab, to complete a long word based on the first two or three letters
  2. column mode editing, that is, change several letters in the same columns across multiple lines

Another problem of micro is that it is impossible to copy from and paste into it in Windows through PuTTY.

Otherwise, they have the following features that are important for text editing:

  1. syntax highlighting, that is, keywords in a certain programming language will be highlighted in color. This will help you to identify misspelt keywords, since they won’t be highlighted.
  2. Searching and replacing words.
  3. undo and redo.
  4. auto indent, that is, when you press enter to open a new line, the new line will be indented the same amount as the previous line automatically.
About

Blogs on physics research and educational activities of Jing LIU, an assistant professor in physics at the University of South Dakota. He is an experimental physicist developing novel particle detectors for astroparticle physics and civil use.