O caractere &
tem um significado especial no lado de substituição de um comando sed s
:
replacement may contain the special character & to refer to that portion of the pattern space which matched, and the special escapes through to refer to the corresponding matching sub-expressions in the regexp.
Para torná-lo literal, você precisa escapar, \&
Ex.
$ echo '&VARIABLE1 = 10000000' | sed 's/&VARIABLE1 = 10000000/&VARIABLE = 1/g'
&VARIABLE1 = 10000000VARIABLE = 1
mas
$ echo '&VARIABLE1 = 10000000' | sed 's/&VARIABLE1 = 10000000/\&VARIABLE = 1/g'
&VARIABLE = 1