Sed - 用一个充满奇怪字符的变量替换一个字符串

我使用sed替换文件中带有变量的字符。该变量基本上是读取文件或网页的内容，其中包含如下所示的多个类似哈希的字符串，这些字符随机生成：

I'm using sed to replace a character in a file with a variable. This variable is basically reading the contents of a file or a webpage which contains multiple hash-like strings like below, which are randomly generated:

define('AUTH_KEY',         'CVo|BO;Qt1B|+GE}+h2/yU7h=5`/wRV{>%h.b_;s%S8-p|>qpf]|/Vf@`&[g~*:&');
define('SECURE_AUTH_KEY',  '{G2-<^jWRd7]2,?]6hhM^*asg.2C.+k=gf33-m+ZK_{Mt|q*<ELF4|gPjyxtTh!)');
define('LOGGED_IN_KEY',    'jSNo9Z;5d]tzZoh-QQ`{M-&~y??$R({:*m`0={67=+mF?L.e+R{;)+4}qCAAHz=C');
define('NONCE_KEY',        '19Vt4=%8j/Z-&~ni0S<]9)J^~sy9dh|h9M_RX2#K0]F9+.v+[BP1d&B&}-FTKIJ,');
define('AUTH_SALT',        'jr7f?T|@Cbo]XVAo}N^ilkvD>dC-rr]5{al64|?_Hz }JG$yEi:_aU )Olp YAD+');
define('SECURE_AUTH_SALT', 'hm#Z%O!X_mr?lM|>>~r-?F%wi R($}|9R[):4^NTsj+gS[qnv}7|+0<9e-$DJjju');
define('LOGGED_IN_SALT',   'tyPHBOCkXZh_4H;G|^.&|^#JPB/f;{}y_Orj!6AH?@wovx+KKtTZ A[HMS9SZJ|N');
define('NONCE_SALT',       'Eb-/t 5D-vPV9I--8F<[^lcherGv.g+|7p6;+xP|5g6P}tup1K.vuHAQ=uWZ#}H^');

变量定义如下：

KEY=$(cat keyfile)

sed语法：

sed -i "s/stringtoreplace/$KEY/" /path/to/file

我也尝试过不同的变体，使用单引号，变量周围的引号

I've also tried different variations, using single-quotes, quotes around the variables

sed -i "s/stringtoreplace/"$KEY"/" /path/to/file

sed -i "s/stringtoreplace/"${KEY}"/" /path/to/file

sed -i "s/stringtoreplace/'$KEY'/" /path/to/file

我认为我强力每一种可能的方式放置报价，我不知道如何逃脱随机生成的字符，如。我继续收到以下错误：

I think I "brute-forced" every way possible to put quotes and I don't know how to escape randomly generated characters like those. I keep getting the following error:

未终止 s 命令

有关如何用奇怪的哈希变量替换字符串的任何建议？

Any suggestions on how to replace the string with the weird-hash-like variable?