export LC_ALL = "POSIX"
readonly may not have spaces around the
+= operator. This is the same as for regular variable assignments:
export var = value # Invalid: spaces around = export var =value # Invalid: space before = export var= value # Invalid: space after = export var=value # Valid
This is because each individual argument to these commands is interpreted as a string in the format
name=value. By adding spaces, you are instead passing the three strings
value, none of which follow this format.
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