command line - What are the best-practices for implementing a CLI tool in Perl? -

-

I am implementing a CLI tool using Perl. What are the best practices we can do here?

As a prelude, I spent 3 years in engineering and a major financial company in Pearl for a lot Applying Complex Command Line ToolsSet The following ideas are basically part of our team's design guidelines.

User interface

  1. Command line options: Provide default value as much as possible.

  2. Any scalable parameter for any command with more than 2 options

  3. The readable option names are if the command line Length is a concern for non-interactive calling (for example, some unnoted heritage sphere has fewer limitations on command lines), provide less aliases - GetOpt :: Long allows easily.

  4. At the very least, print all the options - the default value in "Help".

    Better yet, print all the options "present" value (for example if a parameter and value are given with "help", the support message will print the value of the parameter from the command line In this way, people can collect command line string for complex commands and can actually verify it by adding "-help" before it runs.

  5. Unix Standard Conference Follow non-zero if your The disease can be useful (such as capturing the value / grepping / whatnot) output, so make sure that any error / diagnostic message is sent to STDERR. They can be easily divided.

    6. < Li>

    Ideally, the user "redirects" through input line output parameters - this provides a very simple way for people to build complex pipes using your order Need to It is OK to get an error message - Logfile is the option.

  6. If there is a side effect of the command, then there is a great idea when the "whatif / no_post" option is .

implementation

  1. As mentioned earlier, do not invent the wheel again. Use Standard Command Line Parameter Handling Module - MooseX :: Getopt, or Getopt :: Long

  2. For Getopt :: Long, all parameters have the same hash as an individual form Resist the variable from Many useful samples include that the CLI argument object to the hash creator.

  3. Ensure that your error messages are clear and informative ... e.g. "$!" Include a separate "file not found" vs. "file not readable" errors to spend extra 1 minute and 2 lines in your code in any IO-related error messages, because 30 minutes in the productive emergency Is opposed to spending because a non-readable file error was misused due to the operation Operations "There is no input file" - this is a real life example Land.

  4. Actually CLI is not specific, but validates all the parameters, ideally after receiving them. CLI does not allow "front-end" verification such as webapps, so be super super alert.

  5. As discussed above, in the other reasons already listed for modifying business logic, as a web app, I reapply an existing CLI tool. It had to do - and it is not difficult that the argument is already properly designed module.

Interesting links

I will try to add more bullets while remembering them.


Comments

Post a Comment

Popular posts from this blog

c# - ListView onScroll event -

-
I am programming a simple C # application, and I need a Scallow event on the list view. So I inherited the original ListView class created in ListviewEx witch. I found out how to locate the scroll message from WinAPI and I modified the WndProc method. Now I have this WndProc: protected override zero WndProc (Ref message message) {base.WndProc (Ref I); If (m.msg == WM_VSCROLL) {onScroll (This, New EventArgs ()); }} But the problem is, I do not know how to know about scrolling information. This data should be in wParam, but there is a LOWORD macro ++ like in C in C # and I switch to find the criteria like SB_ below, SB_ENDSCROLL, SB_PAGEUP etc. there any way Need to change the LOWORD macro from C #? Or any other way to find the necessary parameters about scrolling? You can define the WParam constants as the following: Private const int WM_HSCROLL = 0x114; Private Constant WM_VSCROLL = 0x115; Private contact int SBHOZZ = 0; Private Consultant SB_VERT = 1; Private Con...
Read more

PHP - get image from byte array -

-
I am trying to create a back-end for my mobile application. I am sending the content of an image in the body of the HTTP request (output stream) as a byte array, I want to read this stream of bytes in PHP scripts and take back an image. Can anyone tell me how can I do this? Thank you. You can obtain the request body $ body = Reading from file_get_contents ('php: // input'); What you do with that data Depending on you, you can write the data in a file as you mentioned that this is image data, you can drop the data into the object can do. Another option is to use and load the image.
Read more

Linux Terminal Problem with Non-Canonical Terminal I/O app -

-
I have a small app written in C to run on Linux. Part of the app accepts user-input from keyboard , And it uses non-canonical terminal mode so that it can respond to each keystroke. The section of the code that accepts input is a simple task that is called repeatedly in the loop: char get_input () {char C = 0; Int res = reading (input_tamille, & amp; c, 1); If (RSS == 0) 0 returns; If (res == -1) {/ * snip error handling * /} return c; } It reads a letter from the terminal if there is no input within a given time limit, (c_cc [VTIME] value in the vocabulary structure), read () 0 And get_input () is called again It all works very well, I have recently discovered that if you run this app in a terminal window, and then the app Close the terminal window without ending, the app will not exit Received, but CPU intensive launches into an infinite loop, where the read () returns 0 without waiting continued. So how can I get out of the apple if it runs from the terminal win...
Read more