Read-eval-print loop

Implicit cd

Like the Friendly Interactive Shell, Ion also supports executing the cd command automatically when given a path. Paths are denoted by beginning with .///~, or ending with /.

~/Documents # cd ~/Documents
..          # cd ..
.config     # cd .config
examples/   # cd examples/

Multi-line Arguments

If a line in your script becomes too long, appending \ will make Ion ignore newlines and continue reading the next line.

command arg arg2 \
    arg3 arg4 \
    arg 5

Multi-line Strings

If a string needs to contain newlines, you use an open quote. Ion will only begin parsing supplied commands that are terminated. Either double or single quotes can be used.

echo "This is the first line
    this is the second line
    this is the third line"

Prompt Function

The prompt may optionally be generated from a function, instead of a string. Due to the need to perform a fork an capture of its output as prompt, prompts generated from functions aren't as efficient. Below the requirement to use the function with name PROMPT:

    echo -n "${PWD}# "

Key Bindings

There are two pre-set key maps available: Emacs (default) and Vi. You can switch between them with the keybindings built-in command.

keybindings vi
keybindings emacs

Vi keybinding: You can define the displayed indicator for normal and insert modes with the following variables:

$ export VI_NORMAL = "[=] "
$ export VI_INSERT = "[+] "
$ keybindings vi
[+] $