fish shell Cheat Sheet by myounkin

You can find a better cheat sheet here: https:­//g­ith­ub.c­om­/mi­cha­el-­you­nki­n/f­ish­_sh­ell­_ch­eat­sheet

Variables
Three kinds: universal, global, and local. Universal variables are shared btw. all sessions on the computer per user. Global variables are specific to the current fish session, but they are outside of any block scope. Local variables are specific to a particular block scope and are automa­tically erased.

Set a variable as universal with -U, as global with -g, or local with -l. Scoping rules are as follows:
1. If a variable is explicitly set to either universal, global or local, that setting will be honored. If a variable of the same name exists in a different scope, that variable will not be changed.
2. If a variable is not explicitly set to be either universal, global or local, but has been previously defined, the variable scope is not changed.
3. If a variable is not explicitly set to be either universal, global or local and has never before been defined, the variable will be local to the currently executing function. Note that this is different from using the -l or –local flag. If one of those flags is used, the variable will be local to the most inner currently executing block, while without these the variable will be local to the function. If no function is executing, the variable will be global.

Exporting Variables
Export a variable with -x.

Arrays
Store multiple strings in one variable with an array. Access an index:
echo $PATH[3]

Iterate:
for i in $PATH; echo $i is in the path; end

Defini­tion:
set smurf blue small makes an array called smurf containing "­blu­e" and "­sma­ll".

Delete an element:
set -e smurf[1]

Functions
Define a function like so:
function ll
ls -l $argv
end
Access arguments using $argv, call the function using ll.

Jobs
When you execute a command, it starts a job. You can put a job in the background by adding the & suffix. You can suspend a currently running job using Ctrl-Z. You can put the suspended job in the background with bg. Finally, you can list all running jobs with jobs.

Chaining Commands
Each command ends in either a newline or a semicolon. Chain commands using command; and command2 or command; or command2. and and or check the previous command's exit status and act accord­ingly.

Aliases
To define an alias, either make a function:
function ls
command ls --colo­r=auto $argv
end
...or use use alias NAME DEFINITION which does this for you.

Quotes and expansion
Without quotes, variables are expanded and characters are escaped. In double quotes, variables are expanded, but no characters are escaped (except for \", \$, and \\); in single quotes, everything is literal (except for \' and \\).

Command Expansion
Surround the command in parent­heses. If it returns multiple lines, they'll be concat­enated with spaces.

Parameter Expansion
Use find for most globbing. Fish supports ? for any single character (except /), for any string of characters (except /) (including empty string), and * for any string of charac­ters, including the empty string and /.

Files beginning with . are ignored unless a . is the first character of the glob.

Brace Expansion
A comma separated list of characters enclosed in curly braces is expanded to each element of the list is a new parameter:
echo input.{­c,­h,txt}
>> input.c input.h input.txt

Variable Expansion
A $ followed by a string of characters is expanded to the value of the enviro­nmental variable with that name. Surround the variable with braces to separate it from text.

Process Expansion
% followed by a string is expanded into a PID according to the following rules:
1. If the string is self, insert the shell's PID
2. If the string is the ID of a job, insert the process group ID of the job
3. If any child processes match the string, insert their PIDs
4. If any processes owned by the user match the string, insert their PIDs
5. If none of the above matches, then produce an error

Index Range Expansion
Select a range of values from an array using ..:
echo (seq 10)[2..5 1..3]
>> 2 3 4 5 1 2 3