redirecting v4.0.0 scripts' output to a file adds spurious bytes

[programandala-net]

i use fish 4.0.0 on debian 12.9.

after updating fish 3.7.1 to 4.0.0 one of my tools written in fish started giving wrong, strange results.

finally i have isolated the problem and confirmed it does not happen with v3.7.1 (which i temporarily reinstalled for confirmation): when the output of a fish script is redirected to a file, five bytes are added at the start and at the end of the file. both sequences start with an ANSI escape code.

bytes added at the start of the file:

1B 5B 36 20 71

bytes added at the end of the file:

1B 5B 32 20 71

the problem can be reproduced with this "hello.fish":

#!/usr/bin/env fish
# hello.fish
echo hello

./hello.fish # good output to screen
./hello.fish > hello.txt # wrong output to file

first i suspected the problem lies with echo, but the same happens with this "ls.fish":

#!/usr/bin/env fish
# ls.fish
ls

./ls.fish # good output to screen
./ls.fish > ls.txt # wrong output to file

it seems a bug. anyway i've searched the changes of fish 4.0.0, just in case i missed something, but found nothing.

[krobelus]

$ printf '\x1b\x5b\x35\x20\x71' | cat -v
^[[5 q⏎

It's the cursor shaping sequence (from __fish_cursor_xterm). This is an embarassing regression triggered by running fish_vi_key_bindings also in non-interactive shells..
Fixed by 044afef.

As a workaround write your config.fish like this:

status is-interactive || exit
fish_vi_key_bindings