navi/docs/cheatsheet_syntax.md

Cheatsheet syntax

• Syntax overview
• Folder structure
• Variables
• Advanced variable options
• Variable dependency
• Multiline snippets
• Variable as multiple arguments

Syntax overview

Cheatsheets are described in .cheat files that look like this:

% git, code

# Change branch
git checkout <branch>

$ branch: git branch | awk '{print $NF}'

Lines starting with:

• %: determine the start of a new cheatsheet and should contain tags
• #: should be descriptions of commands
• ;: are ignored. You can use them for metacomments
• $: should contain commands that generate a list of possible values for a given argument ℹ️
• @: should contain tags whose associated cheatsheet you want to base on ℹ️

All the other non-empty lines are considered as executable commands.

Folder structure

It's irrelevant how many files are used to store cheatsheets. They can be all in a single file if you wish, as long as you split them accordingly with lines starting with %.

Variables

The interface prompts for variable names inside brackets (eg <branch>).

Variable names should only include alphanumeric characters and _.

If there's a corresponding line starting with $ for a variable, suggestions will be displayed. Otherwise, the user will be able to type any value for it.

If you hit <tab> the query typed will be preferred. If you hit <enter> the selection will be preferred.

Advanced variable options

For lines starting with $ you can use --- to customize the behavior of fzf or how the value is going to be used:

# This will pick the 3rd column and use the first line as header
docker rmi <image_id>

# Even though "false/true" is displayed, this will print "0/1"
echo <mapped>

$ image_id: docker images --- --column 3 --header-lines 1 --delimiter '\s\s+'
$ mapped: echo 'false true' | tr ' ' '\n' --- --map "grep -q t && echo 1 || echo 0"

The supported parameters are:

• --column <number>: extracts a single column from the selected result
• --map <bash_code>: (experimental) applies a map function to the selected variable value
• --prevent-extra: (experimental) limits the user to select one of the suggestions
• --fzf-overrides <arg>: (experimental) applies arbitrary fzf overrides
• --expand: (experimental) converts each line into a separate argument

In addition, it's possible to forward the following parameters to fzf:

• --multi
• --header-lines <number>
• --delimiter <regex>
• --query <text>
• --filter <text>
• --header <text>
• --preview <bash_code>
• --preview-window <text>

Variable dependency

The command for generating possible inputs can implicitly refer other variables by using the <varname> syntax:

# Should print /my/pictures/wallpapers
echo "<wallpaper_folder>"

$ pictures_folder: echo "/my/pictures"
$ wallpaper_folder: echo "<pictures_folder>/wallpapers"

If you want to make dependencies explicit, you can use the $varname syntax:

# If you select "hello" for <x>, the possible values of <y> will be "hello foo" and "hello bar"
echo <x> <y>

# If you want to ignore the contents of <x> and only print <y>
: <x>; echo <y>

$ x: echo "hello hi" | tr ' ' '\n'
$ y: echo "$x foo;$x bar" | tr ';' '\n'

Extending cheatsheets

With the @ same tags from other cheatsheet syntax you can reuse the same variable in multiple cheatsheets.

% dirs, common

$ pictures_folder: echo "/my/pictures"

% wallpapers
@ dirs, common

# Should print /my/pictures/wallpapers
echo "<pictures_folder>/wallpapers"

% screenshots
@ dirs, common

# Should print /my/pictures/screenshots
echo "<pictures_folder>/screenshots"

Multiline snippets

Commands may be multiline:

# This will output "foo\nyes"
echo foo
true \
   && echo yes \
   || echo no

Variable as multiple arguments

# This will result into: cat "file1.json" "file2.json"
cat <jsons>

$ jsons: find . -iname '*.json' -type f -print --- --multi --expand