Fzf: First line of preview replaced with ansi garbage

[runarorama]

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The first line of the preview window is always replaced with some ansi noise. I'm not entirely sure where that's coming from.

For example, if I say:

fzf --preview="echo 'one
two
three'" 

I get the following:

Lines other than the first appear fine and shown as expected, in glorious ANSI colour if applicable.

Any clues on how to debug this?

fzf version 0.17.5 (brew)

[LuRsT]

Hi @runarorama,

It's been a while since you submitted this issue and I can't reproduce it, in the meantime have you figured out the issue, or has it been fixed in a new version of fzf?

[runarorama]

I haven't figured it out, and it's still present as of 0.18.0 (ff95134)

[LuRsT]

Could you try with the newest version: 0.20.0 please?

[runarorama]

Same issue with 0.20.0 (brew)

[junegunn]

fzf uses $SHELL to launch preview command, so it's likely that your $SHELL is injecting those stuff for color configuration.

So try this and see if the problem persists

SHELL=/bin/sh fzf --preview="\echo 'one
two
three'"

[runarorama]

That fixes the issue. My $SHELL is set to /usr/local/bin/fish

[junegunn]

Looks like it's an Xterm control sequence for changing color palette.

(https://superuser.com/questions/647033/xterm-control-sequence-to-get-rgb-value-for-ansi-color)

The current ANSI processor of fzf doesn't understand the pattern, so they are just printed on the screen. I can probably fix this, but your shell, whatever it is, shouldn't be configured to print it out when it runs a command, because you don't want those characters to be included in the output when you run a one-off command.

fish -c ls > /tmp/output

[runarorama]

Mystery solved, then. Thank you! I had a command that sets the colour palette in my config.fish. Hiding that behind a check for an interactive shell solves the issue:

if status --is-interactive
  theme_gruvbox dark
end