### Start Emacs using exec

Source: https://fishshell.com/docs/current/cmds/exec.html

This example demonstrates starting the emacs text editor, which replaces the current fish shell. The session will terminate when emacs exits.

```fish
exec emacs
```

--------------------------------

### Example fish_prompt with svn info

Source: https://fishshell.com/docs/current/cmds/fish_svn_prompt.html

A basic example demonstrating how to include Subversion information in the fish prompt.

```fish
function fish_prompt
    ... 
    printf '%s %s$' $PWD (fish_svn_prompt)
end
```

--------------------------------

### Get Help with Commands

Source: https://fishshell.com/docs/current/tutorial.html

Use 'man' to view documentation for commands in the terminal or 'help' to open Fish's documentation in a web browser. This example shows 'man set'.

```fish
> man set
set - handle shell variables
  Synopsis...

```

--------------------------------

### Conditional execution with 'and' and 'or'

Source: https://fishshell.com/docs/current/cmds/and.html

This example demonstrates chaining commands: 'make' is run, and if it succeeds, 'make install' is executed. If either of these fail, 'make clean' is run.

```fish
make; and make install; or make clean
```

--------------------------------

### Start Fish Shell

Source: https://fishshell.com/docs/current/cmds/fish.html

To simply start an interactive fish shell session.

```bash
fish
```

--------------------------------

### Example output interpretation

Source: https://fishshell.com/docs/current/cmds/time.html

This example demonstrates the output format of the `time` command, showing wall-clock time and CPU time breakdowns for fish and external processes.

```fish
> time string repeat -n 10000000 y\n | command grep y >/dev/null
________________________________________________________
Executed in  805.98 millis    fish           external
   usr time  798.88 millis  763.88 millis   34.99 millis
   sys time  141.22 millis   40.20 millis  101.02 millis
```

--------------------------------

### fish_delta Output Example

Source: https://fishshell.com/docs/current/cmds/fish_delta.html

An example output from running fish_delta, showing new and changed files, along with diff information for a changed completion file.

```fish
> fish_delta
New: /home/alfa/.config/fish/functions/battery.fish
Changed: /home/alfa/.config/fish/test/completions/cargo.fish
---
/home/alfa/.config/fish/test/completions/cargo.fish	2022-09-02 12:57:55.579229959 +0200
+++
/usr/share/fish/completions/cargo.fish	2022-09-25 17:51:53.000000000 +0200
# the output of `diff` follows
```

--------------------------------

### Get current login information

Source: https://fishshell.com/docs/current/cmds/prompt_login.html

This example demonstrates how to directly call the `prompt_login` command to retrieve the current login information, typically displayed as 'user@host'.

```fish
prompt_login
```

--------------------------------

### psub Example: Highlighting Preprocessed C Code

Source: https://fishshell.com/docs/current/cmds/psub.html

This example shows how to use psub with the -f and -s options to highlight preprocessed C code, specifying a custom suffix for the temporary file.

```fish
source-highlight -f esc (cpp main.c | psub -f -s .c)
```

--------------------------------

### psub Example: Comparing Sorted Files

Source: https://fishshell.com/docs/current/cmds/psub.html

This example demonstrates how to use psub to compare the sorted versions of two files by passing their sorted outputs to the diff command.

```fish
diff (sort a.txt | psub) (sort b.txt | psub)
```

--------------------------------

### nextd command example

Source: https://fishshell.com/docs/current/cmds/nextd.html

Demonstrates the usage of nextd by navigating through directories and then moving forward in the history.

```bash
cd /usr/src
# Working directory is now /usr/src

cd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell

prevd
# Working directory is now /usr/src

nextd
# Working directory is now /usr/src/fish-shell
COPY
```

--------------------------------

### Simple Fish Prompt Example

Source: https://fishshell.com/docs/current/cmds/fish_prompt.html

A basic example of a fish_prompt function that displays the current user, hostname, and directory, with the directory color-coded. It utilizes built-in fish variables like $USER and $hostname for simplicity.

```fish
function fish_prompt -d "Write out the prompt"
    # This shows up as USER@HOST /home/user/ >, with the directory colored
    # $USER and $hostname are set by fish, so you can just use them
    # instead of using `whoami` and `hostname`
    printf '%s@%s %s%s%s > ' $USER $hostname \
        (set_color $fish_color_cwd) (prompt_pwd) (set_color --reset)
end
```

--------------------------------

### Configure config.fish

Source: https://fishshell.com/docs/current/tutorial.html

Example of a config.fish file showing how to set environment variables and define functions. Fish executes commands in ~/.config/fish/config.fish on startup.

```fish
> cat ~/.config/fish/config.fish

set -x PATH $PATH /sbin/

function ll
    ls -lh $argv
end
```

--------------------------------

### fish-shell switch command example

Source: https://fishshell.com/docs/current/cmds/switch.html

An example demonstrating how to use the switch command to classify an animal based on the value of the `$animal` variable. It includes a default case for unknown values.

```fish
switch $animal
    case cat
        echo evil
    case wolf dog human moose dolphin whale
        echo mammal
    case duck goose albatross
        echo bird
    case shark trout stingray
        echo fish
    case '*'
        echo I have no idea what a $animal is
end
```

--------------------------------

### Set selection start and end with commandline

Source: https://fishshell.com/docs/current/relnotes.html

Demonstrates using the `commandline` builtin with new options `--selection-start` and `--selection-end` to programmatically set the start and end points of the current selection on the command line.

```fish
commandline --selection-start 10 --selection-end 20
```

--------------------------------

### isatty examples: terminal output

Source: https://fishshell.com/docs/current/cmds/isatty.html

These examples demonstrate cases where isatty should return a zero exit status, indicating a terminal.

```fish
isatty
isatty stdout
isatty 2
echo | isatty 1
```

--------------------------------

### Fish Prompt Example with fish_status_to_signal

Source: https://fishshell.com/docs/current/cmds/fish_status_to_signal.html

An example of how to use fish_status_to_signal within a custom fish shell prompt function to display signal information.

```fish
function fish_prompt
    echo -n (fish_status_to_signal $pipestatus | string join '|') (prompt_pwd) '$ '
end
```

--------------------------------

### Start Fish Shell

Source: https://fishshell.com/docs/current/tutorial.html

Type 'fish' in your current shell to launch the Fish shell. This is the initial prompt you will see.

```fish
> fish
Welcome to fish, the friendly interactive shell
Type help for instructions on how to use fish
you@hostname ~>
```

--------------------------------

### Basic 'begin' and 'end' block

Source: https://fishshell.com/docs/current/cmds/end.html

Demonstrates the basic usage of 'begin' to start a command block and 'end' to terminate it.

```fish
begin
    echo "Inside the block"
end
```

--------------------------------

### Optional Argument Example

Source: https://fishshell.com/docs/current/cmds/argparse.html

Provides an example of using an option with an optional argument, where the argument is directly attached to the flag. This is common for commands like 'grep'.

```fish
grep --color auto
# Here "auto" will be used as the search string,
```

--------------------------------

### Build HTML Documentation with Sphinx-Build

Source: https://fishshell.com/docs/current/contributing.html

Build HTML documentation directly with `sphinx-build`, allowing you to specify the output directory. This example outputs to `/tmp/fish-doc`.

```bash
sphinx-build -j auto -b html doc_src/ /tmp/fish-doc/
COPY
```

--------------------------------

### Run Basic Command

Source: https://fishshell.com/docs/current/tutorial.html

Execute commands by typing the command name followed by its arguments, separated by spaces. This example shows the 'echo' command.

```fish
> echo hello world
hello world
```

--------------------------------

### Example Fish Prompt with Informative Status

Source: https://fishshell.com/docs/current/cmds/fish_hg_prompt.html

An example of a fish_prompt function that enables informative Mercurial status and displays the current directory and Mercurial information.

```fish
function fish_prompt
    ... 
    set -g fish_prompt_hg_show_informative_status
    printf '%s %s$' $PWD (fish_hg_prompt)
end
```

--------------------------------

### Add Ruby's bin directory after Homebrew installation

Source: https://fishshell.com/docs/current/cmds/fish_add_path.html

A common use case is adding the binary directory of software installed via package managers like Homebrew to the PATH.

```fish
> fish_add_path /usr/local/opt/ruby/bin
```

--------------------------------

### Build and Run Unit Tests with Cargo

Source: https://fishshell.com/docs/current/contributing.html

Build the project using Cargo and then run all unit tests. Ensure you have Rust and Cargo installed.

```bash
cargo build
# Run unit tests
cargo test
```

--------------------------------

### Example: Conditional logic based on root user

Source: https://fishshell.com/docs/current/cmds/fish_is_root_user.html

This example demonstrates how to use fish_is_root_user within a function to execute different logic if the user is root. It's a common pattern for adapting script behavior.

```fish
function example --description 'Just an example'
    if fish_is_root_user
        do_something_different
    end
end
```

--------------------------------

### Synopsis of fish_key_reader

Source: https://fishshell.com/docs/current/cmds/fish_key_reader.html

Displays the basic command structure for fish_key_reader. No specific setup is required to run this command.

```fish
fish_key_reader [OPTIONS]
```

--------------------------------

### Fish while loop example with file existence check

Source: https://fishshell.com/docs/current/cmds/while.html

This example demonstrates a while loop that checks for the existence of either 'foo.txt' or 'bar.txt'. It will print 'file exists' and sleep for 10 seconds at each interval, continuing as long as at least one of the files is present.

```fish
while test -f foo.txt; or test -f bar.txt ; echo file exists; sleep 10; end
```

--------------------------------

### Example: Prevent Specific Commands from History

Source: https://fishshell.com/docs/current/cmds/fish_should_add_to_history.html

This example prevents immediate 'vault', 'mysql', or 'ls' commands from being stored in history. Commands starting with a space are still saved.

```fish
function fish_should_add_to_history
    for cmd in vault mysql ls
         string match -qr "^$cmd" -- $argv; and return 1
    end
    return 0
end
```

--------------------------------

### Example of using pushd and popd

Source: https://fishshell.com/docs/current/cmds/popd.html

Demonstrates how to use pushd to add directories to the stack and popd to remove them, showing the changes in the working directory and directory stack.

```fish
pushd /usr/src
# Working directory is now /usr/src
# Directory stack contains /usr/src

pushd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell
# Directory stack contains /usr/src /usr/src/fish-shell

popd
# Working directory is now /usr/src
# Directory stack contains /usr/src
COPY
```

--------------------------------

### Get Modification Time with `path mtime`

Source: https://fishshell.com/docs/current/cmds/path.html

Retrieve the last modification time of given paths in seconds since the Unix epoch. Use `--relative` to get seconds since the start of the command execution. Returns 0 if reading mtime succeeded for any path.

```fish
path mtime [-z | --null-in] [-Z | --null-out] [-q | --quiet] [-R | --relative] [PATH ...]
```

```fish
>_ date +%s
# This prints the current time as seconds since the epoch
1657217847
```

```fish
>_ path mtime /etc/
1657213796
```

```fish
>_ path mtime -R /etc/
4078
# So /etc/ on this system was last modified a little over an hour ago
```

```fish
# This is the same as
>_ math (date +%s) - (path mtime /etc/)
```

--------------------------------

### Synopsis of begin command

Source: https://fishshell.com/docs/current/cmds/begin.html

Shows the different syntaxes for the begin command.

```fish
begin; [COMMANDS ...]; end
{ [COMMANDS ...] }
```

--------------------------------

### Tab Completion Example

Source: https://fishshell.com/docs/current/tutorial.html

Demonstrates basic tab completion for a path. Pressing 'tab' attempts to complete the current word.

```shell
> /pri`tab` => /private/
```

--------------------------------

### Profile Fish Startup

Source: https://fishshell.com/docs/current/cmds/fish.html

Profile fish's startup time and analyze configuration performance.

```bash
fish --profile-startup /tmp/start.prof -ic exit
```

```bash
sort -nk2 /tmp/start.prof
```

--------------------------------

### Example of pushd and popd usage

Source: https://fishshell.com/docs/current/cmds/pushd.html

Demonstrates how to use pushd to add directories to the stack and change the current directory, and how popd removes a directory from the stack. Shows the state of the working directory and directory stack after each operation.

```fish
cd ~/dir1
pushd ~/dir2
pushd ~/dir3
# Working directory is now ~/dir3
# Directory stack contains ~/dir2 ~/dir1

pushd /tmp
# Working directory is now /tmp
# Directory stack contains ~/dir3 ~/dir2 ~/dir1

pushd +1
# Working directory is now ~/dir3
# Directory stack contains ~/dir2 ~/dir1 /tmp

popd
# Working directory is now ~/dir2
# Directory stack contains ~/dir1 /tmp
```

--------------------------------

### Generate random number between 10 and 20 (even step)

Source: https://fishshell.com/docs/current/cmds/random.html

This example generates a random even number between 10 and 20 and counts down to 1. It demonstrates using `random` with start, step, and end arguments within a `seq` command.

```fish
for i in (seq (random 10 2 20) -1 1)
    echo $i
end
```

--------------------------------

### Extract substring using negative start index

Source: https://fishshell.com/docs/current/cmds/string-sub.html

Use a negative `--start` index to specify the starting position relative to the end of the string. The substring will extend to the end of the string.

```fish
>_ string sub --start=-2 abcde
de
```

--------------------------------

### Synopsis of commandline

Source: https://fishshell.com/docs/current/cmds/commandline.html

This shows the basic syntax for using the commandline command. It can take options and a command string.

```fish
commandline [OPTIONS] [CMD]
```

--------------------------------

### Invalid Fish script translation examples

Source: https://fishshell.com/docs/current/contributing.html

Examples of invalid syntax for marking strings for translation in Fish script.

```fish
echo (_ hello)
_ "goodbye"
COPY
```

--------------------------------

### Brace Expansion at Start of Compound Statement

Source: https://fishshell.com/docs/current/language.html

Shows that brace expansion is not performed if braces appear at the start of a compound statement.

```fish
> {echo hello, && echo world}
```

--------------------------------

### Edit PO file example

Source: https://fishshell.com/docs/current/contributing.html

Example of a PO file entry showing msgid (original string) and msgstr (translation).

```po
msgid "%s: No suitable job\n"
msgstr ""
COPY
```

--------------------------------

### isatty examples: non-terminal output

Source: https://fishshell.com/docs/current/cmds/isatty.html

These examples demonstrate cases where isatty should return a non-zero exit status, indicating it is not a terminal.

```fish
echo | isatty
isatty 9
isatty stdout > file
isatty 2 2> file
```

--------------------------------

### Home Directory Expansion with User

Source: https://fishshell.com/docs/current/language.html

The '~' character expands to the home directory. Prepending a username like '~root' expands to that user's home directory.

```fish
ls ~/Music
echo ~root
```

--------------------------------

### Start Fish Shell

Source: https://fishshell.com/docs/current/index.html

Type 'fish' to start a new fish shell session. This command is used when fish is not your default shell.

```fish
> fish
COPY
```

--------------------------------

### prevd command example

Source: https://fishshell.com/docs/current/cmds/prevd.html

Demonstrates the usage of prevd to move backward in directory history after navigating through several directories. It also shows the complementary nextd command.

```fish
cd /usr/src
# Working directory is now /usr/src

cd /usr/src/fish-shell
# Working directory is now /usr/src/fish-shell

prevd
# Working directory is now /usr/src

nextd
# Working directory is now /usr/src/fish-shell
```

--------------------------------

### Start emacs in the background

Source: https://fishshell.com/docs/current/language.html

Starts the emacs text editor in the background, allowing the user to continue using the terminal. Append '&' to any command to run it in the background.

```fish
emacs &
```

--------------------------------

### Extract substring by start and length

Source: https://fishshell.com/docs/current/cmds/string-sub.html

Specify both `--start` and `--length` to extract a substring of a certain length beginning at a specific position. Indices are 1-based.

```fish
>_ string sub -s 2 -l 2 abcde
bc
```

--------------------------------

### Configure Prompt with Disco Theme

Source: https://fishshell.com/docs/current/cmds/fish_config.html

Applies the 'disco' sample prompt for the current session and demonstrates how to save it to configuration files.

```fish
fish_config prompt choose disco
COPY
```

--------------------------------

### Fish Shell example of break command

Source: https://fishshell.com/docs/current/cmds/break.html

This example demonstrates how to use the break command to exit a for loop early. It searches for a pattern in files and stops after the first match.

```fish
for i in *.c
    if grep smurf $i
        echo Smurfs are present in $i
        break
    end
end
```

--------------------------------

### Basic prompt_pwd Usage

Source: https://fishshell.com/docs/current/cmds/prompt_pwd.html

Prints the current working directory, replacing the home directory with '~'.

```fish
>_ cd ~/
>_ echo $PWD
/home/alfa

>_ prompt_pwd
~
```

--------------------------------

### Simple fish_title example

Source: https://fishshell.com/docs/current/cmds/fish_title.html

Sets a custom terminal title that includes the current directory (truncated) and the most recent foreground command. This example demonstrates how to use the argv variable and prompt_pwd.

```fish
function fish_title
    set -q argv[1]; or set argv fish
    # Looks like ~/d/fish: git log
    # or /e/apt: fish
    echo (fish_prompt_pwd_dir_length=1 prompt_pwd): $argv;
end
```

--------------------------------

### Implement false command using return

Source: https://fishshell.com/docs/current/cmds/return.html

This example demonstrates how to implement a function that always fails by using 'return 1'. This is useful for creating custom commands or utility functions.

```fish
function false
    return 1
end
```

--------------------------------

### Print All Functions

Source: https://fishshell.com/docs/current/cmds/functions.html

Calling 'functions' without arguments prints the names of all defined functions, excluding those starting with an underscore. Use the -a or --all option to include functions starting with an underscore.

```fish
functions
```

```fish
functions -a
```

--------------------------------

### Build Fish Shell as a Self-Installing Binary

Source: https://fishshell.com/docs/current/relnotes.html

To build Fish as a self-installing binary, navigate to a clone of the Fish repository and run the 'cargo install' command.

```bash
cargo install --path .
```

--------------------------------

### Theme File Format Example

Source: https://fishshell.com/docs/current/cmds/fish_config.html

Illustrates the structure and syntax of a fish shell theme file, including definitions for light, dark, and unknown color variants.

```fish
# name: 'My Theme'

[light]
# preferred_background: ffffff
fish_color_normal 000000
fish_color_autosuggestion 7f7f7f
fish_color_command 0000ee

[dark]
# preferred_background: 000000
fish_color_normal ffffff
fish_color_autosuggestion 7f7f7f
fish_color_command 5c5cff

[unknown]
fish_color_normal --reset
fish_color_autosuggestion brblack
fish_color_cancel -r
fish_color_command --reset
COPY
```

--------------------------------

### Example: Conditional History Exclusion Based on Directory

Source: https://fishshell.com/docs/current/cmds/fish_should_add_to_history.html

This example prevents 'git pull' commands from being added to history specifically within the '/home/me/my-secret-project/' directory. It checks both the command and the current working directory.

```fish
function fish_should_add_to_history
    # I don't want `git pull`s in my history when I'm in a specific repository
    if string match -qr '^git pull' -- "$argv"
    and string match -qr "^/home/me/my-secret-project/" -- (pwd -P)
        return 1
    end

    return 0
end
```

--------------------------------

### Argparse with Minimum Arguments

Source: https://fishshell.com/docs/current/cmds/argparse.html

Illustrates using argparse with a minimum argument requirement and a simple argument list. This example shows how to ensure at least one argument is provided.

```fish
set -l argv foo
argparse 'h/help' 'n/name' -- $argv
argparse --min-args=1 -- $argv
```

--------------------------------

### Exponentiation and modulo operations

Source: https://fishshell.com/docs/current/cmds/math.html

Shows how to perform exponentiation and modulo operations using the math command.

```fish
math 2 ^ 3
math 10 % 3
```

--------------------------------

### Get Command Exit Status in Fish

Source: https://fishshell.com/docs/current/faq.html

Use the `$status` variable in fish to get the exit status of the last command, equivalent to `$?` in other shells. Commands can also be used directly as conditions in `if` statements.

```fish
somecommand
if test $status -eq 7
    echo "That's my lucky number!"
end
```

```fish
if somecommand
    echo "Command succeeded"
else
    echo "Command failed"
end
```

```fish
somecommand
or someothercommand
```

--------------------------------

### Run a command, stop it, and send to background

Source: https://fishshell.com/docs/current/cmds/bg.html

This demonstrates the typical workflow of starting a long-running command, stopping it with Ctrl-Z, and then resuming it in the background using the 'bg' command.

```fish
> find / -name "*.js" >/tmp/jsfiles 2>/dev/null # oh no, this takes too long, let's press Ctrl-z!
fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has stopped
> bg
Send job 1 'find / -name "*.js" >/tmp/jsfiles 2>/dev/null' to background
> # I can continue using this shell!
> # Eventually:
fish: Job 1, 'find / -name "*.js" >/tmp/jsfil…' has ended
```

--------------------------------

### fish-shell case statement example

Source: https://fishshell.com/docs/current/cmds/case.html

Demonstrates how to use the case statement with a switch to classify an animal based on its name. It includes examples with specific names, multiple names in one case, and a wildcard case.

```fish
switch $animal
    case cat
        echo evil
    case wolf dog human moose dolphin whale
        echo mammal
    case duck goose albatross
        echo bird
    case shark trout stingray
        echo fish
    # Note that the next case has a wildcard which is quoted
    case '*'
        echo I have no idea what a $animal is
end
```

--------------------------------

### Basic Color Usage with set_color

Source: https://fishshell.com/docs/current/cmds/set_color.html

Demonstrates setting foreground colors to red, blue, and a custom hex code, followed by printing text. Includes resetting to normal.

```fish
set_color red; echo "Roses are red"
set_color blue; echo "Violets are blue"
set_color 62A; echo "Eggplants are dark purple"
set_color normal; echo "Normal is nice" # Resets the background too
```

--------------------------------

### Binding a key sequence to a command

Source: https://fishshell.com/docs/current/cmds/bind.html

This example demonstrates how to bind a specific key sequence (e.g., Alt+w) to execute a fish command. The command can be any valid fish command or a special input function.

```fish
bind alt-w forward-word
```

--------------------------------

### Bind command synopsis

Source: https://fishshell.com/docs/current/cmds/bind.html

This shows the various ways the bind command can be invoked, including setting bindings, listing them, and querying information about functions and keys.

```fish
bind [(-M | --mode) MODE] [(-m | --sets-mode) NEW_MODE] [--preset | --user] [-s | --silent] KEYS COMMAND ...
bind [(-M | --mode) MODE] [--preset] [--user] [--color WHEN] [KEYS]
bind [-a | --all] [--preset] [--user] [--color WHEN]
bind (-f | --function-names)
bind (-K | --key-names)
bind (-L | --list-modes)
bind (-e | --erase) [(-M | --mode) MODE] [--preset] [--user] [-a | --all] | KEYS ...
```

--------------------------------

### Omit Range Limits in Fish Index Expansions

Source: https://fishshell.com/docs/current/relnotes.html

Range limits in index range expansions like '$var[$start..$end]' can be omitted. '$start' defaults to 1 and '$end' defaults to -1 (the last item).

```fish
echo $var[1..]
echo $var[..-1]
echo $var[..]
```

--------------------------------

### Run Script with Initialization Command

Source: https://fishshell.com/docs/current/cmds/fish.html

Execute a script after sourcing another file for initialization.

```bash
fish --init-cmd "source otherfile" script.fish
```

--------------------------------

### Extract substring by negative start and end indices

Source: https://fishshell.com/docs/current/cmds/string-sub.html

Combine negative `--start` and `--end` indices to extract a substring relative to the end of the string. Note that `--length` is mutually exclusive with `--end`.

```fish
>_ string sub -s 2 -e -1 abcde
bcd
```

--------------------------------

### Extract substring by negative start and end indices with specific range

Source: https://fishshell.com/docs/current/cmds/string-sub.html

Extract a substring using negative start and end indices to define a specific range within the string. The `--length` option cannot be used with `--end`.

```fish
>_ string sub -s -3 -e -2 abcde
c
```

--------------------------------

### Redirecting output of a begin block

Source: https://fishshell.com/docs/current/cmds/begin.html

Illustrates how to redirect all output from a 'begin' block to a file.

```fish
begin
    echo $xml_header
    echo $html_header
    if test -e $file
        ...
    end
    ...
end > out.html
```

--------------------------------

### Install libcxx on OS X Snow Leopard

Source: https://fishshell.com/docs/current/relnotes.html

Use this command to install the C++11 standard library on OS X 10.6 if you encounter the dyld error. This is necessary for fish version 2.5 and later on this specific OS version.

```shell
sudo port -v install libcxx
```

--------------------------------

### Fish Shell: Builtin Output Before Data Read Example

Source: https://fishshell.com/docs/current/relnotes.html

Demonstrates how builtins can now output before all data is read, making them usable for pipes where the previous command hasn't finished yet. This is a significant change for streaming data processing.

```fish
string replace --all 'foo' 'bar' < file.txt
```

--------------------------------

### Bind Key Sequence in Fish Shell

Source: https://fishshell.com/docs/current/relnotes.html

Shows how to bind a sequence of two keys using the new human-readable syntax in Fish shell. This example binds 'ctrl-x' followed by 'alt-c' to execute 'do something'.

```fish
bind ctrl-x,alt-c 'do something'
```

--------------------------------

### Install Package with Wildcard in Name

Source: https://fishshell.com/docs/current/language.html

When using commands like 'apt install' that perform their own wildcard matching, literal glob characters in arguments must be quoted to prevent fish from expanding them prematurely. This ensures the command receives the intended pattern.

```fish
apt install "ncurses-*"
```

--------------------------------

### Fish Shell Security Fix Example

Source: https://fishshell.com/docs/current/relnotes.html

This example demonstrates how fish uses Unicode non-characters internally for markers. Previously, these could be incorrectly outputted on command substitution, posing a minor security risk if external programs processed this output. This has been fixed.

```fish
echo \UFDD2HOME
```

--------------------------------

### isatty command synopsis

Source: https://fishshell.com/docs/current/cmds/isatty.html

The synopsis shows the basic usage of the isatty command. It can optionally take a file descriptor as an argument.

```fish
isatty [FILE_DESCRIPTOR]
```

--------------------------------

### Implement command alias with completions

Source: https://fishshell.com/docs/current/cmds/complete.html

Use the -w or --wraps option to make a command inherit all completions from another command, effectively creating an alias for completion purposes.

```fish
complete -c hub -w git
```

--------------------------------

### List all functions

Source: https://fishshell.com/docs/current/cmds/functions.html

Lists all functions, including those starting with an underscore.

```APIDOC
## functions -a

### Description
Lists all functions, even those whose name starts with an underscore.

### Method
functions

### Parameters
#### Options
- **-a** or **--all** - Lists all functions, even those whose name starts with an underscore.

### Request Example
```
functions -a
```

### Response Example
```
# Displays a list of all functions, including hidden ones
```
```

--------------------------------

### Get function details

Source: https://fishshell.com/docs/current/cmds/functions.html

Reports detailed information about function definition paths and properties.

```APIDOC
## functions -D FUNCTION

### Description
Reports the path name where the specified function is defined or could be autoloaded, `stdin` if the function was defined interactively or on the command line or by reading standard input, **-** if the function was created via source, and `n/a` if the function isn’t available. If the **--verbose** option is also specified then five lines are written: the path name, if the function was copied, the path name to where the function was originally defined, otherwise `autoloaded`, `not-autoloaded` or `n/a`, the line number within the file or zero if not applicable, `scope-shadowing` or `no-scope-shadowing`, and the function description.

### Method
functions

### Parameters
#### Options
- **-D** or **--details** - Reports detailed information about the function.
- **-v** or **--verbose** - Make some output more verbose.

### Request Example
```
functions -D my_function
functions -D -v my_function
```

### Response Example
```
# Example output for functions -D my_function:
# /path/to/my_function.fish
# Example output for functions -D -v my_function:
# /path/to/my_function.fish
# autoloaded
# 10
# scope-shadowing
# A brief description of my_function
```
```

--------------------------------

### Display help for the help command itself in fish

Source: https://fishshell.com/docs/current/cmds/help.html

To understand how to use the 'help' command, you can pass the '--help' option to it.

```fish
help --help
```

--------------------------------

### Windows .exe completion for myprog.exe

Source: https://fishshell.com/docs/current/cmds/complete.html

On Windows, use this syntax to specify completions that apply only to executables with the .exe extension.

```fish
complete -c myprog.exe ...
```

--------------------------------

### string sub

Source: https://fishshell.com/docs/current/cmds/string.html

Extracts a substring from each string argument based on start, end, or length parameters.

```APIDOC
## string sub

### Description
Prints a substring of each string argument. The substring can be defined by start and end indices, or by a start index and a length. Indices are 1-based and can be negative to count from the end of the string.

### Method
string sub

### Parameters
#### Path Parameters
- **STRING ...** (string) - Required - The string(s) to extract substrings from.

#### Options
- **-s, --start START** (integer) - The 1-based starting index of the substring. Defaults to 1.
- **-e, --end END** (integer) - The 1-based ending index of the substring.
- **-l, --length LENGTH** (integer) - The length of the substring. Mutually exclusive with --end.
- **-q, --quiet** - Suppress output and only return exit status.

### Examples
```
>_ string sub --length 2 abcde
ab

>_ string sub -s 2 -l 2 abcde
bc

>_ string sub --start=-2 abcde
de

>_ string sub --end=3 abcde
abc

>_ string sub -e -1 abcde
abcd

>_ string sub -s 2 -e -1 abcde
bcd
```
```

--------------------------------

### Translate PO file entry

Source: https://fishshell.com/docs/current/contributing.html

Example of a translated PO file entry with a Swedish translation.

```po
msgid "%s: No suitable job\n"
msgstr "%s: Inget passande jobb\n"
COPY
```

--------------------------------

### Build HTML Documentation with Cargo Xtask

Source: https://fishshell.com/docs/current/contributing.html

Use this command to build an HTML version of the documentation locally. The output will be in `target/fish-docs/html`.

```bash
cargo xtask html-docs
COPY
```

--------------------------------

### Execute command on signal

Source: https://fishshell.com/docs/current/cmds/trap.html

This example demonstrates how to set up a trap to print a stack trace whenever the SIGUSR1 signal is sent to the shell. Signal names are case-insensitive and the SIG prefix is optional.

```fish
trap "status --print-stack-trace" SIGUSR1
```

--------------------------------

### Show all completions for a command

Source: https://fishshell.com/docs/current/cmds/complete.html

Display all currently defined completions for a given command.

```fish
complete -c git
```

--------------------------------

### Get List Length

Source: https://fishshell.com/docs/current/tutorial.html

Use the `count` command to determine the number of elements in a list variable.

```fish
> count $PATH
5
```

--------------------------------

### Join strings with a separator

Source: https://fishshell.com/docs/current/cmds/string-join0.html

Demonstrates joining strings with a specified separator. The `...` is used as a separator in this example.

```fish
>_ seq 3 | string join ...
1...2...3
```

--------------------------------

### Return command synopsis

Source: https://fishshell.com/docs/current/cmds/return.html

This shows the basic syntax for the return command. It can optionally take an integer argument.

```fish
return [N]
```

--------------------------------

### Get the length of strings

Source: https://fishshell.com/docs/current/cmds/string.html

Calculates and returns the length of the provided strings. The `-q` option suppresses output.

```fish
string length [-q | --quiet] [STRING ...]
```