Unable to understand the syntax of the command find

The string {} in find is replaced by the pathname of the current file.

The semicolon is used for terminating the shell command invoked by find utility.

It needs to be escaped, or quoted, so it won't be interpreted by the shell, because ; is one of the special characters used by shell (list operators).

See also: Why are the backslash and semicolon required with the find command's -exec option?

The -exec command may be followed by any number of arguments that make up the command that is to be executed for each file found. There needs to be some way to identify the last argument. This is what \; does. Note that other things may follow after the -exec switch:

find euler/ -iname "*.c*" -exec echo {} \; -or -iname "*.py" -exec echo {} \;

(This finds all c-files and python files in the euler directory.)

The reason that exec does not require the full command to be inside quotes, is that this would require escaping a lot of quotes inside the command, in most circumstances.

The (escaped) semicolon is needed so that "find" can tell where the arguments to the exec'd program end (if there are any) and additional arguments to "find" begin.