Eshell

Eshell is a shell written in EmacsLisp elisp.

Eshell is included as of Emacs 21.

Overview

Eshell is a shell that has its own syntax, but it can also run elisp code. It’s more than just an elisp REPL.

Aliases

You can create an alias (a short nickname for a longer command) in Eshell with the alias command (alias on its own lists your aliases):

~$ alias e  'eshell-source-file $1'
~$ alias o  'find-file $1'
~$ alias oo 'find-file-other-window $1'
~$ alias l  'ls'
~$
~$ alias
> alias e eshell-source-file $1
> alias o find-file $1
> alias oo find-file-other-window $1
> alias l ls

Or you can define them in your InitFile

(use-package em-alias
  :config
  (eshell/alias  "e"  "eshell-source-file $1")
  (eshell/alias  "o"  "find-file $1")  
  (eshell/alias  "l"  "ls"))

Aliases are saved automatically.

See EshellAlias

Functions

You can write functions in Eshell just as you would in elisp:

~$ (defun square (x) (* x x))
~$ square 3
9

(You do not need ( parentheses ) around functions when you call them from eshell.

To make a function available in eshell from your InitFile, use the eshell/ prefix:

(defun eshell/square (x)
  (* x x))

see EshellFunctions

Shell Scripting

A shell script (commonly with an .esh extension) is a file where eshell evaluates each line as if it were an eshell input.

Run a script with eshell-source-file file.esh

# A hash is a comment in an Eshell script
echo "uwu, meow!" > file.txt
cat file.txt > file2.txt
cat *2.txt

(defun square (x)
  (* x x))

square 2

Which outputs:

~$ eshell-source-file test.esh
> uwu, meow!
> square
> 4

Customization

Standard I/O works well in eshell, but ncurses interfaces like htop and nano won’t run in it; we can tell eshell to run such commands in AnsiTerm instead, which is a full emulated VT100 terminal.

(append '("htop" "vim" "ssh") eshell-visual-commands)

see also

AnsiTerm – VT100 emulator in Emacs

external links

CategoryEshell CategoryShell