mjhjmtu

I want to define a function, and call that function every n seconds. As an example:

function h
 echo hello
end

Calling h works:

david@f5 ~> h
hello

But when using watch, it doesn't...

watch -n 60 "h"

...and I get:

Every 60.0s: h f5: Wed Oct 10 21:04:15 2018

sh: 1: h: not found

How can I run watch in fish, with the function I've just defined?

There is no easy way. By default watch uses /bin/sh to run commands but takes -x:

 -x, --exec
 Pass command to exec(2) instead of sh -c which reduces the need to use extra quoting to get the
 desired effect.

However, nothing will not work with fish because h function is not
exported to environment:

$ watch -n 5 --exec fish -c h
Every 5.0s: fish -c h comp: Wed Oct 10 21:30:14 2018

fish: Unknown command 'h'
fish:
h
^

In bash you could export a variable to environment with export -f
and use it inside watch like this:

$ h1 () 
> echo hi
> 
$ type h1
h1 is a function
h1 ()

 echo hi

$ export -f h1
$ watch -n 60 bash -c h1
Every 60.0s: bash -c h1 comp: Wed Oct 10 21:29:22 2018

hi

If you use fish you can create a wrapper script and call it with watch:

$ cat stuff.sh
#!/usr/bin/env fish

function h
 date
end

h

$ watch -n5 ./stuff.sh

Also note that fish has . and source so you can define function
in another file and be able to re-use it in other scripts like that:

$ cat function
function h
 echo hi
end
$ cat call.sh
#!/usr/bin/env fish

. function

h
$ watch ./call.sh