fish(1)

Quick Info

Fish initialization file ~/.config/fish/config.fish

Switch between different key bindings:

fish_default_key_bindings to use default key bindings
fish_vi_key_bindings to use vi key bindings

Variables

Available scopes

local variable local to a block
global variable global to shell instance
universal variable universal to all shell instances + preserved across shell restart

Set/Unset Variables

set <name> [<values>]
    -l  local scope
    -g  global scope
    -U  universal scope
    -e  erase variable
    -S  show verbose info
    -x  export to ENV
    -u  unexport from ENV

Lists

In fish all variables are lists (start with index 1, but lists can't contain lists.

set foo a b c d

echo $foo[1]      # a
echo $foo[-1]     # d
echo $foo[2..3]   # b c
echo $foo[1 3]    # a c

$ can be seen as dereference operator.

set foo a; set a 1337
echo $$foo  # outputs 1337

Cartesian product.

echo file.{h,cc}
# file.h file.cc

echo {a,b}{1,2}
# a1 b1 b2

Special Variables (Lists)

$status      # exit code of last command
$pipestatus  # list of exit codes of pipe chain

$CMD_DURATION   # runtime of last command in ms

`*PATH`

Lists ending with PATH are automatically split at : when used and joined with : when exported to the environment.

set -x BLA_PATH a:b:c:d
echo $BLA_PATH              # a b c d
env | grep BLA_PATH         # BLA_PATH=a:b:c:d

Command Handling

# sub-commands are not run in quotes
echo "ls output: "(ls)

I/O redirection

# 'noclobber', fail if 'log' already exists
echo foo >? log

Control Flow

`if` / `else`

if grep foo bar
    # do sth
else if grep foobar bar
    # do sth else
else
    # do sth else
end

`switch`

switch (echo foo)
case 'foo*'
    # do start with foo
case bar dudel
    # do bar and dudel
case '*'
    # do else
end

`while` Loop

while true
    echo foo
end

`for` Loop

for f in (ls)
    echo $f
end

Functions

Function arguments are passed via $argv list.

function fn_foo
    echo $argv
end

Autoloading

When running a command fish attempts to autoload a function. The shell looks for <cmd>.fish in the locations defined by $fish_function_path and loads the function lazily if found.

This is the preferred way over monolithically defining all functions in a startup script.

Helper

functions         # list al functions
functions foo     # describe function 'foo'
functions -e foo  # erase function 'foo'

funced foo        # edit function 'foo'
                  # '-e vim' to edit in vim

Prompt

The prompt is defined by the output of the fish_prompt function.

function fish_prompt
    set -l cmd_ret
    echo "> "(pwd) $cmd_ret" "
end

Use set_color to manipulate terminal colors.

Useful Builtins

# history
history search <str>   # search history for <str>
history merge          # merge histories from fish sessions

# list
count $var            # count elements in list

# string
string split SEP STRING

Keymaps

  Shift-Tab ........... tab-completion with search
  Alt-Up / Alt-Down ... search history with token under the cursor
  Alt-l ............... list content of dir under cursor
  Alt-p ............... append '2>&1 | less;' to current cmdline

Debug

  status print-stack-trace .. prints function stacktrace (can be used in scripts)
  breakpoint ................ halt script execution and gives shell (C-d | exit
                              to continue)

Notes