Final answer:
To find how many files are linked to file1, look at the number in the second field of the 'ls -l' command output, which indicates the count of hard links.
Step-by-step explanation:
To determine how many files are linked with file1 given the output of the ls command, you need to look for the second field in the long format listing of the file which indicates the number of hard links. The command ls -l would display this information, where the relevant output might look something like '-rw-r--r-- 3 user group 1024 Jan 1 00:00 file1'. In this example, the number 3 signifies that there are two other files linked to file1, because the file itself counts as one link.