cheatsheets/fish-shell.md

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---
title: Fish shell
category: CLI
layout: 2017/sheet
prism_languages: [fish]
updated: 2017-10-16
weight: -1
---
### Keys
| Shortcut | Description |
| --- | --- |
| `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}
### Help
| `Alt H` | Help on word (man) |
| `Alt W` | Help on word (short descriptions) |
| `Alt L` | List directory on cursor |
{: .-shortcuts}
## Function
### Writing functions
```fish
function my_function --description "My description"
···
end
```
### Conditional
```fish
if test -f foo.txt
···
else if test -f bar.txt
···
else
···
end
```
### Combining tests
```fish
if test -f foo.txt && test -f bar.txt
```
```fish
if test -f foo.txt -a -f bar.txt
```
```fish
if test \( -f foo.txt \) -a -f \( bar.txt \)
```
### Events
#### Emitting
```fish
emit my_event
```
#### Listening
```fish
function myhook --on-event my_event
···
end
```
This lets you hook onto events, such as `fish_prompt`.
## Completions
### Creating completions
#### ~/.fish/completions/mycommand.fish
```fish
complete -c mycommand ...
complete -c mycommand ...
complete -c mycommand ...
```
### Options
```fish
complete \
-c # command
-s # short option
-l # long option
-r, --require-parameter
-f, --no-files
-x # exclusive (-r -f)
-n '__fish_use_subcommand' # condition
--description ".."
```
#### Example
```fish
complete -c $cmd \
-n '__fish_use_subcommand' \
-x -a hello \
--description 'lol'
```
### Conditions
| 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` |
#### Example
```fish
complete -c ruby -s X -x -a '(__fish_complete_directories (commandline -ct))' --description 'Directory'
```
### Examples
Start each example with `complete -c cmdname`
```fish
-x
# no filename completion
```
```fish
-s d -x -a "read skip"
# -d {read|skip}
```
```fish
-s d -x
# -d <something>
```
```fish
-s f -r
# -f FILE
```
```fish
-s f -l force
# -f, --force
```
```fish
-a "(cat /etc/passwd | cut -d : -f 1)"
# first argument as filename
```