Tham khảo tài liệu 'professional information technology-programming book part 86', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Writing Scripts for the Command Line The PHP language provides certain functionality that is particularly useful for writing command-line scripts. You will rarely if ever use these features in the web environment but they are described in the following sections. Character Mode Output When you re producing web output you use the br tag to produce a simple line break in the output. When it is sent to a web page the newline character n causes a line break in the HTML source but it is not visible in the rendered web page. Command-line scripts however produce text-only output so you must use the newline character to format your output. If your script produces any output you should always include n after the last item has been displayed. You can also take advantage of the fixed-width character mode when running command-line scriptsfor instance by spacing output into columns. The printf function allows you to use width and alignment format characters which have no effect on HTML output unless they re contained in PRE tags. For more information refer to Lesson 6 Working with Strings. Command-Line Arguments You can pass arguments to a shell script by simply appending them after the script name itself. The number of arguments passed can be found in the variable argc and the arguments themselves are stored in a numerically indexed array named argv. Arguments The identifier names argc and argv are used for historic reasons. They originated in C and are now widely used in many programming languages. In PHP argc is assigned for convenience only you could of course perform count argv to find out how many arguments were passed to the script. The argv array will always contain at least one element. Even if no additional arguments are passed to the script argv 0 will contain the name of the script itself and argc will be 1. The script in Listing requires exactly two arguments to be passed. Otherwise an error message appears and the script terminates. The output produced shows .
