Building a Binary with arguments and options - flags package in golang

In this post, I will provide information about building a go program with arguments and options.

Typically, an executable can contain

• Arguments: Go expects these to be provided after all the options.
• options (specified with - & provided with an option value). Example: "-srcDir /tmp". Go calls these as "flags".
• flags: True if specified, else false. Example: "-e" to enable/disable. Go doesn't support this type of flags !!!

Here is a sample binary I built to test go flags. Sample outputs running the above binary:

• How to get help text?

 

So, we get help text free if we use flags package !! 

• Run the program without any inputs:

• Run the program without any additional arguments

                

• Run the program with an additional argument

      

• 
  

Some drawbacks I see with go flags package:

• As we saw earlier, go flags package doesn't provide a way for us to specify mandatory options. We need to either write additional code (like I provided above) or use custom packages such as go-flags
• go doesn't support true/false kind of flags

TBD:

• flagSet (building subcommands)

References:

https://golang.org/pkg/flag/
https://blog.rapid7.com/2016/08/04/build-a-simple-cli-tool-with-golang/
https://gobyexample.com/command-line-flags
https://stackoverflow.com/questions/31786215/can-command-line-flags-in-go-be-set-to-mandatory/31786480#:~:text=The%20flag%20package%20does%20not,halt%20with%20an%20error%20message