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README.md

cheat.sh logo

Unified access to the best community driven cheat sheets repositories of the world.

Let's imagine for a moment that there is such a thing as an ideal cheat sheet. How it should look like? What features should it have?

  • concise — it should be concise; it should contain only things you need and nothing else;
  • fast — it should be possible to use it instantly;
  • comprehensive — it should contain answers for every question you could have;
  • universal — it should be available everywhere, as soon as needed, without any preparations;
  • unobtrusive — it does not distract you from your main task when you are using it;
  • tutoring — it helps you to learn the subject;
  • inconspicuous — it should be possible to use it completely unnoticed.

Such a thing does exist.

Features

cheat.sh

  • has simple curl/browser interface;
  • covers 55 programming languages, several DBMSes, and more than 1000 most important UNIX/Linux commands;
  • provides access to the best community driven cheat sheets repositories in the world as well as to StackOverflow;
  • available everywhere, no installation needed;
  • ultrafast, returns answers, as a rule, within 100 ms;
  • has a convenient command line client, cht.sh, that is very advantageous and helpful, though not mandatory;
  • can be used directly from code editors, without opening a browser and not switching your mental context;
  • supports a special mode (stealth mode), where it can be used fully invisibly, not even touching a key and not making a sound.

Usage

To get a cheat sheet for a UNIX/Linux command from a command line, query the service using curl or any other HTTP/HTTPS client specifying the name of the command in the query:

    curl cheat.sh/tar
    curl cht.sh/curl
    curl https://cheat.sh/rsync
    curl https://cht.sh/tr

As you can see, you can use both HTTPS and HTTP to access the service, and both the long (cheat.sh) and the short (cht.sh) service names.

Here tar, curl, rsync, and tr are names of the UNIX/Linux commands, you want to get cheat sheets for.

If you don't know the name of the command you need, you can search for it using the ~KEYWORD notation. For example, to see how you can make snapshots of a filesystem/volume/something else:

    curl cht.sh/~snapshot

Programming languages cheat sheets are located not directly in the root namespace, but in special namespaces, dedicated to them:

    curl cht.sh/go/Pointers
    curl cht.sh/scala/Functions
    curl cht.sh/python/lambda

To get the list of available programming language cheat sheets, do a special query :list:

    curl cht.sh/go/:list

(almost) each programming language has a special page, named :learn, that describes the language basics (that's a direct mapping from the "Learn X in Y" project). It could be a good starting point, if you've just started learning a language.

If there is no cheat sheet for some programming language query (and it is almost always the case), it is generated on the fly, basing on available cheat sheets and answers on StackOverflow. Of course, there is no guarantee that the returned cheat sheet will be a 100% hit, but it is almost always exactly what you are looking for.

Try these (and your own) queries to get the impression of that, how the answers look like:

    curl cht.sh/go/reverse+a+list
    curl cht.sh/python/random+list+elements
    curl cht.sh/js/parse+json
    curl cht.sh/lua/merge+tables
    curl cht.sh/clojure/variadic+function

If you don't like an answer for some of your queries, you can pick another one: for that, repeat the query with an additional parameter /1, /2 etc. appended:

    curl cht.sh/python/random+string
    curl cht.sh/python/random+string/1
    curl cht.sh/python/random+string/2

Cheat sheets are formatted as code of the queried programming language (at least we are trying our best to do so) so they can be pasted into a program in this language directly. Text comments, if there are any, are formatted according to the language syntax.

    $ curl cht.sh/lua/table+keys
    -- lua: retrieve list of keys in a table

    local keyset={}
    local n=0

    for k,v in pairs(tab) do
      n=n+1
      keyset[n]=k
    end

    --[[
       [ Note that you cannot guarantee any order in keyset. If you want the
       [ keys in sorted order, then sort keyset with table.sort(keyset).
       [ 
       [ [lhf] [so/q/12674345] [cc by-sa 3.0]
       ]]

If you don't need text comments in the answer, you can eliminate them using a special option ?Q:

    $ curl cht.sh/lua/table+keys?Q
    local keyset={}
    local n=0

    for k,v in pairs(tab) do
      n=n+1
      keyset[n]=k
    end

And if you don't need syntax highlighting, switch it off using ?T. You can combine the options together:

    curl cht.sh/go/reverse+a+list?Q
    curl cht.sh/python/random+list+elements?Q
    curl cht.sh/js/parse+json?Q
    curl cht.sh/lua/merge+tables?QT
    curl cht.sh/clojure/variadic+function?QT

Full list of all options described below and in /:help.

Try your own queries. Follow these rules:

  1. Try to be more specific (/python/append+file is better than /python/file and /python/append);
  2. Ask practical question if possible (yet theoretical question are possible too);
  3. Ask programming language questions only; specify the name of the programming language as the section name;
  4. Separate words with + instead of spaces;
  5. Do not use special characters, they are ignored anyway.

Read more about the programming languages queries below.

Command line client, cht.sh

The cheat.sh service has its own command line client (cht.sh), that, comparing to quering the service directly with curl, has several useful features:

  • Special shell mode with a persistent queries context and readline support;
  • Queries history;
  • Clipboard integration;
  • Tab completion support for shells (bash, fish, zsh);
  • Stealth mode.

To install the client:

    curl https://cht.sh/:cht.sh > ~/bin/cht.sh
    chmod +x ~/bin/cht.sh

Now, you can use cht.sh instead of curl, and write your queries in more natural way, with spaces instead of +:

    $ cht.sh go reverse a list
    $ cht.sh python random list elements
    $ cht.sh js parse json

It is even more convenient to start the client in a special shell mode:

    $ cht.sh --shell
    cht.sh> go reverse a list

If all your queries are supposed to be about the same language, you can change the context of the queries and spare repeating the programming language name:

    $ cht.sh --shell
    cht.sh> cd go
    cht.sh/go> reverse a list

or even start the client in this context:

    $ cht.sh --shell go
    cht.sh/go> reverse a list
    ...
    cht.sh/go> join a list
    ...

If you want to change the context, you can do it with the cd command, or if you want do a single query for some other language, just prepend it with /:

    $ cht.sh --shell go
    ...
    cht.sh/go> /python dictionary comprehension
    ...

If you want to copy the last answer into the clipboard, you can use the c (copy) command, or C (ccopy, without comments).

    cht.sh/python> append file
    #  python - How do you append to a file?

    with open("test.txt", "a") as myfile:
        myfile.write("appended text")
    cht.sh/python> C
    copy: 2 lines copied to the selection

Type help for other internal cht.sh commands.

	cht.sh> help
	help    - show this help
	hush    - do not show the 'help' string at start anymore
	cd LANG - change the language context
	copy    - copy the last answer in the clipboard (aliases: yank, y, c)
	ccopy   - copy the last answer w/o comments (cut comments; aliases: cc, Y, C)
	exit    - exit the cheat shell (aliases: quit, ^D)
	id [ID] - set/show an unique session id ("reset" to reset, "remove" to remove)
	stealth - stealth mode (automatic queries for selected text)
	update  - self update (only if the scriptfile is writeable)
	version - show current cht.sh version
	/:help  - service help
	QUERY   - space ceparated query staring (examples are below)
				  cht.sh> python zip list
				  cht.sh/python> zip list
				  cht.sh/go> /python zip list

Tab completion

To activate tab completion support for cht.sh, add the :bash_completion script to your ~/.bashrc:

    $ curl https://cheat.sh/:bash_completion > ~/.bash.d/cht.sh
    $ . ~/.bash.d/cht.sh
    $ # and add . ~/.bash.d/cht.sh to ~/.bashrc

Stealth mode

One of the important properties of any real cheat sheet, is that it could be used fully unnoticed.

cheat.sh can be used completely unnoticed too. The cheat.sh client, cht.sh, has a special mode, called stealth mode, using that you don't even need to touch your keyboard to open some cheat sheet.

In this mode, as soon as you select some text with the mouse (and thus it is added into the selection buffer of X Window System or into the clipboard) it's used as a query string for cheat.sh, and the correspondent cheat sheet is automatically shown.

Let's imagine, that you are having an online interview, where your interviewer asks you some questions using a shared document (say Google Docs) and you are supposed to write your coding answers there (it's possible too that you'll type in the questions on your own, just to show to the interviewer that you've heard it right).

When using the stealth mode of cht.sh, the only thing you need to do in order to see a cheat sheet for some question, is to select the question using the mouse. If you don't want any text in the answers and the only thing you need is code, use the Q option when starting the stealth mode.

You: Hi!                                            | $ cht.sh --shell python
She: Hi!                                            | cht.sh/python> stealth Q
She: Are you ready for a small interview?           | stealth: you are in the stealth mode; select any text
She: Just a couple of questions                     | stealth: selections longer than 5 words are ignored
She: We will talk about python                      | stealth: query arguments: ?Q
She: Let's start from something simple.             | stealth: use ^C to leave this mode
She: Do you know how to reverse a list in python?   |
You: Sure                                           |
You: (selecting "reverse a list")                   | stealth: reverse a list
                                                    | reverse_lst = lst[::-1]
You: lst[::-1]?                                     |
She: Good.                                          |
She: Do you know how to chain a list of lists?      |
You: (selecting "chain a list of lists")            | stealth: chain a list of lists
                                                    | import itertools
                                                    | a = [["a","b"], ["c"]]
                                                    | print list(itertools.chain.from_iterable(a))
You: May I use external modules?                    |
She: What module do you want to use?                |
You: itertools                                      |
She: Yes, you may use it                            |
You: Ok, then:                                      |
You: itertools.chain.from_iterable(a)               |
She: Good. Let's try something harder.              |
She: What about quicksort implementation?           |
You: (selecting "quicksort implementation")         | stealth: quicksort implementation
You: Let me think about it.                         | (some big and clumsy lowlevel implementation shown)
You: Well...(starting typing it in)                 | def sort(array=[12,4,5,6,7,3,1,15]):
                                                    |     less = []
She: (seeing your ugly pascal style)                |     equal = []
She: Could you write it more concise?               |     greater = []
                                                    |     if len(array) > 1:
You: What do you mean?                              |         pivot = array[0]
                                                    |         for x in array:
She: I mean,                                        |             if x < pivot: less.append(x)
She: do you really need all these ifs and fors?     |             if x == pivot: equal.append(x)
She: Could you may be just use filter instead?      |             if x > pivot: greater.append(x)
                                                    |         return sort(less)+equal+sort(greater)
You: quicksort with filter?                         |     else:
                                                    |         return array
She: Yes                                            |
You: (selecting "quicksort with filter")            | stealth: quicksort with filter
You: Ok, I will try.                                | return qsort(filter(lt, L[1:]))+[pivot] \
You: Something like this?                           |     +qsort(filter(ge, L[1:]))
You: qsort(filter(lt, L[1:]))+[pivot] \             |
       + qsort(filter(ge, L[1:]))                   |
                                                    |
She: Yes! Perfect! Exactly what I wanted to see!    |
                                                    |

Or course, it is just fun, and you should never cheat in your coding interviews, because you know what happens when you do.

when you lie in your interview

Editors integration

You can use cheat.sh directly from the editor (Vim and Emacs are currently supported). Instead of opening your browser, googling, browsing Stack Overflow and eventually copying the code snippets you need into the clipboard and later pasting them into the editor, you can achieve the same instantly and without leaving the editor at all!

Here is how it looks like in Vim:

  1. If you have a question while editing a program, you can just type your question directly in the buffer and press <leader>KK. You will get the answer to your question in pager. (with <leader>KB you'll get the answer in a separate buffer).

  2. If you like the answer, you can manually paste it from the buffer or the pager, or if you are lazy you can use <leader>KP to paste it below/under your question (or replace you question using <leader>KR). If you want the answer without the comments, <leader>KC replays the last query toggling them.

Vim

asciicast

Emacs

  • cheat-sh.el — Emacs support (available also at cheat.sh/:emacs)
  • cheat.sh/:emacs-ivy — Emacs support for ivy users

asciicast

Special pages

There are several special pages (their names are always starting with a colon), that are not cheat sheets and have special meaning.

Getting started:

    :help               description of all special pages and options
    :intro              cheat.sh introduction, covering the most important usage questions
    :list               list all cheat sheets (can be used in a subsection too: /go/:list)

Command line client cht.sh and shells support:

    :cht.sh             code of the cht.sh client
    :bash_completion    bash function for tab completion
    :bash               bash function and tab completion setup
    :fish               fish function and tab completion setup
    :zsh                zsh function and tab completion setup

Editors support:

    :vim                cheat.sh support for Vim
    :emacs              cheat.sh function for Emacs
    :emacs-ivy          cheat.sh function for Emacs (uses ivy)

Other pages:

    :post               how to post new cheat sheet
    :styles             list of color styles
    :styles-demo        show color styles usage examples

Search

To search for a keyword, use the query:

    /~keyword

In this case search is not recursive — it is conducted only in a pages of the specified level. For example:

    /~snapshot          look for snapshot in the first level cheat sheets
    /scala/~currying     look for currying in scala cheat sheets

For a recursive search in all cheat sheets, use double slash:

    /~snapshot/r         look for snapshot in all cheat sheets

You can use special search options after the closing slash:

    /~shot/bi           case insensitive (i), word boundaries (b)

List of search options:

    i   case insensitive search
    b   word boundaries
    r   recursive search

Programming languages cheat sheets

Cheat sheets related to programming languages are organized in namespaces (subdirectories), that are named according to the programming languages.

For each supported programming language there are several special cheat sheets: its own sheet, hello, :list and :learn. Say for lua it will look like:

    lua
    lua/hello
    lua/:list
    lua/:learn

Some languages has the one-liners-cheat sheet, 1line:

    perl/1line
  • hello describes how you can start with the language — install it if needed, build and run its programs, and it shows the "Hello world" program written in the language;
  • :list shows all topics related to the language
  • :learn shows a learn-x-in-minutes language cheat sheet perfect for getting started with the language.
  • 1line is a collection of one-liners in this language
  • weirdness is a collection of examples of weird things in this language

cheat.sh usage

At the moment, cheat.sh covers the 55 following programming languages (alphabetically sorted):

Prefix Language Basics One-liners Weirdness StackOverflow
arduino/ Arduino
assembly/ Assembly
awk/ AWK
bash/ Bash
basic/ BASIC
bf/ Brainfuck
c/ C
chapel/ Chapel
clean/ Clean
clojure/ Clojure
coffee/ CoffeeScript
cpp/ C++
csharp/ C#
d/ D
dart/ Dart
delphi/ Dephi
dylan/ Dylan
eiffel/ Eiffel
elixir/ Elixir
elisp/ ELisp
elm/ Elm
erlang/ Erlang
factor/ Factor
fortran/ Fortran
forth/ Forth
fsharp/ F#
go/ Go
groovy/ Groovy
haskell/ Haskell
java/ Java
js/ JavaScript
julia/ Julia
kotlin/ Kotlin
lisp/ Lisp
lua/ Lua
matlab/ MATLAB
ocaml/ OCaml
perl/ Perl
perl6/ Perl 6
php/ PHP
pike/ Pike
python/ Python
python3/ Python 3
r/ R
racket/ Racket
ruby/ Ruby
rust/ Rust
scala/ Scala
scheme/ Scheme
swift/ Swift
tcsh/ Tcsh
tcl/ Tcl
objective-c/ Objective-C
vb/ VisualBasic
vbnet/ VB.Net

Cheat sheets sources

Instead of creating yet another mediocre cheat sheet repository, we are concentrating our efforts on creation of a unified mechanism to access selected existing well developed and good maintained cheat sheet repositories covering topics of our interest: programming and operating systems usage.

cheat.sh uses selected community driven cheat sheet repositories and information sources, maintained by thousands of users, developers and authors all over the world (in the Users column number of contributors/number of stars is shown):

Cheat sheets Repository Users Creation Date
UNIX/Linux, programming cheat.sheets 6/54 May 1, 2017
UNIX/Linux commands tldr-pages/tldr 541/17360 Dec 8, 2013
UNIX/Linux commands chrisallenlane/cheat 105/4193 Jul 28, 2013
Programming languages adambard/learnxinyminutes-docs 1096/5285 Jun 23, 2013
Go a8m/go-lang-cheat-sheet 29/3034 Feb 9, 2014
Perl pkrumnis/perl1line.txt 4/165 Nov 4, 2011
Programming languages StackOverflow 9M Sep 15, 2008

Pie diagram reflecting cheat sheets sources distribution (by number of cheat sheets on cheat.sh originating from a repository):

cheat.sh cheat sheets repositories

How to contribute

How to edit a cheat sheet

If you want to edit a cheat.sh cheat sheet, you should edit it in the upstream repository. You will find the name of the source repository in a browser, when you open a cheat sheet. There are two github buttons in the bottom of the page: the second one is the button of the repository, whom belongs the current cheat sheet.

You can edit the cheat sheet directly in your browser (you need a github account for it). There is a edit button in the top right corner. If you click on it, an editor will be open. There you will change the cheat sheet (under the hood: the upstrem repository is forked, your changes are commited in the forked repository, a pull request to the upstream repository owner is sent).

cheat.sh cheat sheets repositories

How to add a cheat sheet

If you want to add a cheat sheet, you have one of the following ways:

  • Add it to one of the external cheat sheets repositories; you should decide on your own what is the best repository for your cheat sheet;
  • Add it to the local cheat.sh repository (cheat.sheets) on github (fork, commit, pull request);
  • Post it on cheat.sh using curl or a web browser (cheat.sh/:post).

If you want to change an existing cheat sheet, you have to find the original repository (when you open a cheat sheet in a browser, you see the repository's github button in the bottom of the cheat sheet), the cheat sheet is coming from, and change it there. After some time the changes will be synchronized on cheat.sh.

How to add a cheat sheet repository

If you want to add a cheat sheet repository to cheat.sh, please open an issue:

Please specify the name of the repository, and give its short description.