ut is a local variable that initially takes the value of ab and can be modified later in the script. Its purpose and functionality may depend on the specific context and code surrounding it, but it appears to be used as a flag or condition variable within the script.
If its unused then try deleting the line and seeing if anything changes.
Probably an occams razor stype situation. The simplest explanation is that the previous scripter was planning to use the variable, didnt, then copy and pasted some stuff.