LANGUAGE » SHELL_SCRIPT » FISH

Flow control

Last updated:
Reference:fishshell.com
Man page:test

Condition ​

[[ ]] does not exist. [ ] exist but test is preferred.

fish
if not grep fish /etc/shells
    echo 'No fish'
else if test $number -gt 5 -o $argv[1] = 'string is equal'
    echo Complex condition
else
    echo Got nothing
end

To check if directory is empty or not (reference):

fish
if test -n "$(find $DIR -maxdepth 0 -empty)"
    echo "$DIR is empty!"
end

For loop ​

Loop files:

fish
for file in *.txt
    cp $file $file.bak
end

Loop list of numbers:

fish
for x in (seq 5)
    touch file_$x.txt
end

Break:

fish
for var in a b c
    if break_from_loop
        break
    end
end

While loop ​

fish
while true
    echo 'Loop forever'
end

Read file line by line in loop:

fish
while read --line keyvalue
    export $keyvalue
end < ~/.local/environment

Switch ​

fish
switch (uname)
    case Linux
        echo Hi Tux!
    case Darwin
        echo Hi Hexley!
    case FreeBSD NetBSD DragonFly
        echo Hi Beastie!
    case '*'
        echo Hi, stranger!
end