site/docs/3.1/cmds/contains.html
contains [OPTIONS] KEY [VALUES...]
contains tests whether the set VALUES contains the string KEY. If so, contains exits with status 0; if not, it exits with status 1.
The following options are available:
-i or --index print the word indexNote that, like GNU tools and most of fish's builtins, contains interprets all arguments starting with a - as options to contains, until it reaches an argument that is -- (two dashes). See the examples below.
If $animals is a list of animals, the following will test if it contains a cat:
if contains cat $animalsecho Your animal list is evil!end
This code will add some directories to $PATH if they aren't yet included:
for i in ~/bin /usr/local/binif not contains $i $PATHset PATH $PATH $iendend
While this will check if hasargs was run with the -q option:
function hasargsif contains -- -q $argvecho '$argv contains a -q option'endend
The -- here stops contains from treating -q to an option to itself. Instead it treats it as a normal string to check.