3.3 Built-in commands

Several commands are built-in in Eshell. In order to call the external variant of a built-in command foo, you could call *foo. Usually, this should not be necessary. You can check what will be applied by the which command:

     ~ $ which ls
     eshell/ls is a compiled Lisp function in `em-ls.el'
     ~ $ which *ls
     /bin/ls

If you want to discard a given built-in command, you could declare an alias, Aliases. Example:

     ~ $ which sudo
     eshell/sudo is a compiled Lisp function in `em-unix.el'
     ~ $ alias sudo '*sudo $*'
     ~ $ which sudo
     sudo is an alias, defined as "*sudo $*"

If you would prefer to use the built-in commands instead of the external commands, set eshell-prefer-lisp-functions to t.

Some of the built-in commands have different behaviour from their external counterparts, and some have no external counterpart. Most of these will print a usage message when given the --help option.

addpath

Adds a given path or set of paths to the PATH environment variable, or, with no arguments, prints the current paths in this variable.

alias

Define an alias (see Aliases). This does not add it to the aliases file.

date

Similar to, but slightly different from, the GNU Coreutils date command.

define

Define a varalias. See Variable Aliases.

diff

Use Emacs's internal diff (not to be confused with ediff). See Comparing Files.

grep

agrep

egrep

fgrep

glimpse

The grep commands are compatible with GNU grep, but use Emacs's internal grep instead.

info

Same as the external info command, but uses Emacs's internal Info reader.

jobs

List subprocesses of the Emacs process, if any, using the function list-processes.

kill

Kill processes. Takes a PID or a process object and an optional signal specifier.

listify

Eshell version of list. Allows you to create a list using Eshell syntax, rather than Elisp syntax. For example, ‘listify foo bar’ and ("foo" "bar") both evaluate to ("foo" "bar").

locate

Alias to Emacs's locate function, which simply runs the external locate command and parses the results. See Dired and `find'.

make

Run make through compile. See Running Compilations under Emacs.

occur

Alias to Emacs's occur. See Other Search-and-Loop Commands.

printnl

Print the arguments separated by newlines.

cd

This command changes the current working directory. Usually, it is invoked as ‘cd foo’ where foo is the new working directory. But cd knows about a few special arguments:

When it receives no argument at all, it changes to the home directory.

Giving the command ‘cd -’ changes back to the previous working directory (this is the same as ‘cd $-’).

The command ‘cd =’ shows the directory stack. Each line is numbered.

With ‘cd =foo’, Eshell searches the directory stack for a directory matching the regular expression ‘foo’ and changes to that directory.

With ‘cd -42’, you can access the directory stack by number.

su

sudo

Uses TRAMP's su or sudo method to run a command via su or sudo.

3.3.1 Built-in variables

Eshell knows a few built-in variables:

$+

This variable always contains the current working directory.

$-

This variable always contains the previous working directory (the current working directory from before the last cd command).

$_

It refers to the last argument of the last command.

$$

This is the result of the last command. In case of an external command, it is t or nil.

$?

This variable contains the exit code of the last command (0 or 1 for Lisp functions, based on successful completion).