Update fish.md (formatted from #1758) (#1764)

Co-authored-by: EmilySeville7cfg <EmilySeville7cf@gmail.com>
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@ -9,41 +9,81 @@ weight: -1
### Keys
| Shortcut | Description |
| --- | --- |
| `^A ←` _/_ `^E →` | Move to line beginning/end |
| `Alt ←` _/_ `Alt →` | Move word |
| `^U` | Delete to beginning |
| `^W` | Delete to previous `/` |
| `^D` | Delete next character |
| `Alt D` | Delete next word |
| `^C` | Cancel line |
| `Alt P` | Page output |
| --- | --- |
| `Alt ↑` _/_ `Alt ↓` | Previous _/_ next arguments |
| `Alt E` _/_ `Alt V` | Open in external editor |
| `^L` | Repaint screen |
{: .-shortcuts}
| Shortcut | Description |
| --- | --- |
| `^A ←`/`^E →` | Move to the line beginning/end |
| `Alt ←`/`Alt →` | Jump to the previous/next word |
| `↑`/`↓` | Switch to the previous/next command |
| `Alt ↑`/`Alt ↓` | Switch to the previous/next arguments |
| --- | --- |
| `^U` | Delete to the beginning |
| `^C` | Cancel the line |
| --- | --- |
| `Alt H` | Show the command man page description |
| `Alt W` | Show the short command description |
### Help
### Sample program
| `Alt H` | Help on word (man) |
| `Alt W` | Help on word (short descriptions) |
| `Alt L` | List directory on cursor |
{: .-shortcuts}
```fish
#!/usr/bin/env fish
echo 'Hello from Fish!'
```
### Comments
```fish
# my comment
```
### Printing text
```fish
echo 'Hello from Fish!'
# or
printf '%s\n' 'Hello from Fish!'
```
Print the string with a trailing `\n`.
### Reading from stdin
```fish
read my_variable
```
Reads the string to a variable `my_variable`.
### Loops
```fish
for i in (seq 1 10)
...
end
```
## Variables
### Defining and erasing
```fish
set my_variable "Hello from Fish!"
```
# Declare the global/local variable:
set my_variable 'Hello from Fish!'
```fish
i# Remove the variable:
set --erase my_variable
```
### Slicing
```fish
echo $my_variable[1..10]
echo $my_variable[2..]
echo $my_variable[..-2]
```
## Numbers
### Incrementing and decrementing
```fish
@ -51,62 +91,62 @@ set my_variable (math $my_variable + 1)
set my_variable (math $my_variable - 1)
```
### Slicing
### Arithmetic
```fish
set my_variable $another_variable[1..10]
set my_variable $another_variable[2..]
set my_variable $another_variable[..-2]
echo (math 1 + 2)
```
## Arithmetic
| Operator | Performs |
| --- | --- |
| `+` | Addition |
| `-` | Subtraction |
| `*` | Multiplication |
| `/` | Division |
| `%` | Modulo |
| `^` | Exponentiation |
```fish
math 1 + 2
```
## Strings
| Operator | Performs |
| --- | --- |
| `+` | Addition |
| `-` | Subtraction |
| `*` | Multiplication |
| `/` | Division |
| `%` | Modulo |
| `^` | Exponentiation |
{: .-shortcuts}
### Matching
## String manipulation
Match the string against a regular expresion:
```fish
string match --regex --entire 'Fish' 'Hello from Fish!'
```
| Pattern | Matches |
| --- | --- |
| `x?` | Zero or one `x` chars |
| `x*` | Any count `x` chars |
| `x+` | One or more `x` chars |
| `x{n}` | n times `x` chars |
| `x{n,m}` | n to m times `x` chars |
| `x{n,}` | n or more times `x` chars |
| `[xy]` | `x` or y char |
| `[^xy]` | not `x` or y char |
| --- | --- |
| `\w` | Word character |
| `\d` | Digit character |
| `\W` | Not word character |
| `\D` | Not digit character |
Perl compatible regular expressions are described here.
### Replacing
```fish
# Replaces the first match
string replace --regex 'Fish' 'fish' 'Hello from Fish!'
# Replaces all matches
string replace --regex --all 'Fish' 'fish' 'Hello from Fish!'
```
| Pattern | Matches |
| --- | --- |
| `x?` | Zero or one `x` chars |
| `x*` | Any count `x` chars |
| `x+` | One or more `x` chars |
| `x{n}` | n times `x` chars |
| `x{n,m}` | n to m times `x` chars |
| `x{n,}` | n or more times `x` chars |
| `x{n,}` | n or more times `x` chars |
| `[xy] ` | `x` or y char |
| `[^xy]` | not `x` or y char |
{: .-shortcuts}
## Conditionals
| Class | Description |
| --- | --- |
| `\w` | Word character |
| `\d` | Digit character |
| `\W` | Not word character |
| `\D` | Not digit character |
{: .-shortcuts}
### Conditionals
### If/else
```fish
if test $my_variable -lt $another_variable
@ -118,56 +158,88 @@ else
end
```
| Operator | Meaning |
### Comparisons
#### Numbers
| Number operator | Meaning |
| --- | --- |
| `-lt` | [L]ess [t]han |
| `-eq` | [Eq]ual |
| `-gt` | [G]reater [t]han |
| `-le` | [L]ess than or [e]qual to |
| `-ge` | [G]reater than or [e]qual to |
| `-ne` | [N]ot [E]qual |
#### Strings
| String operator | Meaning |
| --- | --- |
| `==` | [Eq]ual |
| `!=` | [N]ot [E]qual |
#### Files
| File operator | Meaning |
| --- | --- |
| `-f` | [F]ile exists |
| `-d` | [D]irectory exists |
| `-r` | File or directory exists and [r]eadable |
| `-w` | File or directory exists and [w]ritable |
| `-x` | File or directory exists and e[x]ecutable |
{: .-shortcuts}
## Loops
## Process communication
### Writing to files
```fish
for i in (seq 1 10)
...
end
# Overwrite file
echo 'Hello from Fish!' > my_file
# Append to file
echo 'Hello from Fish!' >> my_file
```
## Command substitution
### Piping
```fish
set my_variable (math $my_variable + 1)
my_command | another_command
```
Passes the first command stdout output as an input to a second command.
### Command substitution
```fish
echo (math $my_variable + 1)
```
The `(...)` expression is substituted with the output of the command inside it.
### Process substitution
```fish
echo (math $my_variable + 1 | psub)
```
The `(... | psub)` expression is substituted with a temporary file with the command's output.
## Functions
### Defining and erasing
```fish
function my_function --description "My description"
# Declare the function
function my_function --description 'My description'
···
end
```
```fish
# Remove the function
functions --erase my_function
```
### Event handling
```fish
function my_hook --on-event my_event
···
end
```
## Events
### Emitting
@ -176,56 +248,74 @@ end
emit my_event
```
Emits an event that can be picked up by other functions.
### Event handling
```fish
function my_hook --on-event my_event
···
end
```
Reacts to the `my_event` event.
## Abbreviations
### Defining and erasing
```fish
abbr --add my_abbreviation echo "Hello from Fish!"
# Declare the abbreviation
abbr --add grh "git reset --hard HEAD"
```
```fish
abbr --erase my_abbreviation
# Remove the abbreviation
abbr --erase grh
```
## Completions
### Defining and erasing
### Defining completions
```fish
complete --command mycommand --arguments 'install uninstall'
complete --command mycommand --short-option 'h' --long-option 'help' --description 'Display help'
```
| Option | Description |
| --- | --- |
| `--arguments` | Arguments to the command itself or option |
| `--short-option` | Short option |
| `--long-option` | Long option |
| `--no-files` | Don't suggest files |
| `--force-files` | Suggest files |
| `--condition` | Display the hint only when a given condition is true |
| `--description` | Description |
Declares the completion for a command.
### Removing completions
```fish
complete --command mycommand --erase
```
| Option | Description |
| --- | --- |
| `--arguments` | Arguments to command itself or option |
| `--short-option` | Short option |
| `--long-option` | Long option |
| `--no-files` | Don't suggest files |
| `--force-files` | Suggest files |
| `--condition` | Display hint only when condition is true |
| `--description` | Description |
{: .-shortcuts}
## Useful built-in functions
| Condition | Description
| --- | ---
| `-n __fish_complete_directories STRING DESCRIPTION` | performs path completion on STRING, allowing only directories, and giving them the description DESCRIPTION.
| `-n __fish_complete_path STRING DESCRIPTION` | performs path completion on STRING, giving them the description DESCRIPTION.
| `-n __fish_complete_groups` | prints a list of all user groups with the groups members as description.
| `-n __fish_complete_pids` | prints a list of all processes IDs with the command name as description.
| `-n __fish_complete_suffix SUFFIX` | performs file completion allowing only files ending in SUFFIX. The mimetype database is used to find a suitable description.
| `-n __fish_complete_users` | prints a list of all users with their full name as description.
| `-n __fish_print_filesystems` | prints a list of all known file systems. Currently, this is a static list, and not dependent on what file systems the host operating system actually understands.
| `-n __fish_print_hostnames` | prints a list of all known hostnames. This functions searches the fstab for nfs servers, ssh for known hosts and checks the /etc/hosts file.
| `-n __fish_print_interfaces` | prints a list of all known network interfaces.
| `-n __fish_print_packages` | prints a list of all installed packages. This function currently handles Debian, rpm and Gentoo packages.
| `-n __fish_use_subcommand` |
| `-n __fish_seen_subcommand_from init` |
| Function | Description |
| --- | --- |
| `__fish_seen_argument` | Check whether the specified argument is used |
| `__fish_seen_subcommand_from` | Check whether the specified subcommand is used |
| `__fish_use_subcommand` | Check whether any subcommand is used |
| --- | --- |
| `__fish_complete_directories` | Complete directories with the specified letters in their name |
| `__fish_complete_suffix` | Complete files with the specified suffix |
| --- | --- |
| `__fish_complete_users` | List all users |
| `__fish_complete_groups` | List all user groups |
| `__fish_print_hostnames` | List all host names |
| `__fish_complete_pids` | List all PIDs |
| `__fish_print_filesystems` | List all known filesystems |
| `__fish_print_interfaces` | List all network interfaces |