How to create a horizontal line?

[bound-variable]

One way to do it in the shell is with printf %"$COLUMNS"s |tr " " "─'"

Another way is with printf '%.s─' $(seq 1 $(tput cols))

But when I try to enter this with run '<code>' it fails saying the command isn't found in $PATH.

[Andriamanitra]

Do it without the quotes:

run printf "hello"

Although if you want to use shell syntax for pipes you will need to run the command in a shell like sh or bash:

run sh -c 'printf %10s | tr " " "-"'

And if you want the horizontal line to appear in your buffer rather than in the infobar you should use textfilter instead of run:

textfilter sh -c 'printf %10s | tr " " "-"'

A couple (easier?) ways to do the same thing if you're using fish shell, ruby, or python:

textfilter fish -c 'string repeat -n10 -'
textfilter ruby -e 'puts "-" * 10'
textfilter python3 -c 'print("-" * 10)'

[bound-variable]

Excellent, but I see that querying $COLUMNS doesn't work, unfortunately.

[Andriamanitra]

Yeah the shell that is started does not know about the width of your terminal since it's running in the background (instead of in your terminal). Even if you do tput cols it will likely just return the default of 80 characters.

[dustdfg]

A bit off topic but is it about custom window decorations?

[bound-variable]

Negative. It's about creating dividers between content.