How do I start TextEditor from the command line?

Here are some possible answers, all using the 'open' command-line utility.

The -a option means "open the file argument with the named application":

open -a TextEdit file.txt

The -e option means "open the file argument with the TextEdit application":

open -e file.txt

The -t option means "open the file with the default application for editing text files, as determined via LaunchServices". By default, this will be /Applications/TextEdit.app; however, it's possible for this setting to get overridden:

open -t file.txt

Finally, any file that's of the "text" type will get opened by the application bound to the text type if you just say open file.txt. You can use the "file" command to reveal what the operating system thinks the file type is: file file.txt. So, for example, if you renamed "file.txt" to just "textfile" then open textfile would still open it in the default text-file editing application, as long as file textfile still thought that "textfile" was actually a text file.

A short 'help' file on open can be found by running

open --help

Or you can read the whole manual with

man open

The default text editor is TextEdit. You can open a text file in there by using open -a:

$ open -a TextEdit hi.txt

If you want to use another app, just put it's name in, like this:

$ open -a Coda index.html

There are two ways:

If your default text editor is TextEdit, you can simply use

open -t file.txt

to open it in TextEditor.

If your default text editor is not TextEdit, and you want to open it in TextEdit specifically, you can use

/Applications/TextEdit.app/Contents/MacOS/TextEdit file.txt

Either of those can be made an alias in your shell config file, of course.