Some of them might be, and some might not be. There is another form of the chmod command that uses octal numbers to encode the permissions. Since most novice UNIX users are just confused by this, we will not mention it further, although you might run across it. The man pages explain it in detail for the curious. While users should realize that command names are really just arbitrary symbols, users should also know that UNIX was developed on very slow, clunky teletypes that printed 10 characters per second by people who were not professional typists.
Most commands also have some vague rationale for the names.
Grep is one of them. Grep is used a great deal by UNIX users. The simplest use of grep is to ask it to find a string in a file. If the word appears more than once on a single line, that line is printed only once. One of these is -l which prints out only the file name if the string is found.