from pathlib import Path
p = Path("/home/rain/.config/foot/foot.ini")
text = p.read_text()
old_lines = [
    "# foot does not expand env variables in the `shell=` value, so we have to",
    "# go through `sh -c` to make the parent's $SHELL take effect. When foot",
    "# is launched from a fish session, $SHELL is /bin/fish, and foot runs fish.",
    "# When launched from bash, $SHELL is /bin/bash, and foot runs bash. The",
    "# default fallback is /bin/bash if $SHELL is unset for any reason.",
    'shell=sh,-c,"exec ${SHELL:-/bin/bash} -i"',
]
new_lines = [
    "# kaiser runs zsh as the login shell. Hardcode /usr/bin/zsh here.",
    "# foot does NOT expand $SHELL in shell= (it passes the literal string",
    "# to its child process), so the sh,-c trick makes foot try to exec a",
    '# binary literally named "${SHELL:-/bin/bash}" and die with',
    '# "No such file or directory". Point shell= at the binary directly.',
    "shell=/usr/bin/zsh",
]
old = "\n".join(old_lines)
new = "\n".join(new_lines)
assert old in text, "old block not found in foot.ini"
text = text.replace(old, new, 1)
p.write_text(text)
print("OK, new size:", len(text))