I have found the following code snippet (sh):

```
    TESTFILE=$TEST_PATH/test.out
    if [ -f $TESTFILE ]
    then
        exec < $TESTFILE
    else
        echo "$TEST_PATH: no test.out file"
    fi

```

the focus of my question is, what is this line doing? (the rest i understand!)

```
        exec < $TESTFILE

```

The file is not executable, nor is another process invoked, and i am having no luck finding what exec does on a plain text file.