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Shell Structure

Explaining the inner workings of all the kernel shells

Kernel shells can be built by implementing two different interfaces and base classes. Why two? Because the shell handler relies on:

  • BaseShell and IShell: To hold shell type and initialization code

  • BaseShellInfo<ShellType> and IShellInfo: To hold shell commands and the base shell

To learn more about general information about shells, consult the page below:

ShellsWhat is a shell?

If you want to know about Nitrocid-specific additions, read on.

Return codes

The kernel exceptions can be used as return codes, though you'll have to reference to a class, called KernelExceptionTools, to be able to get an error code by exception type using the GetErrorCode() function. In addition to that, you can also use it with an instance of a kernel exception instance, in case you've wrapped the code with the try...catch clause and that you're catching all the KernelException errors, which almost all APIs throw on either a failure condition or an invalid operation.

All kernel exception codes consist of 10000 added with the enumeration number of the kernel exception type.

Here's a minimal example of what exit does when you're trying to exit the mother shell:

public override int Execute(CommandParameters parameters, ref string variableValue)
{
    if (ShellManager.IsOnMotherShell())
    {
        TextWriters.Write(Translate.DoTranslation("You can't exit the mother shell. Did you mean to log out of your account, shut the kernel down, or reboot it?"), KernelColorType.Error);
        return KernelExceptionTools.GetErrorCode(KernelExceptionType.ShellOperation);
    }
    ShellManager.KillShell();
    return 0;
}

Error codes

The error code variable, MESHErrorCode, holds information about the last process error code, whether it's a success (a zero value) or a failure (non-zero value). In addition to what Terminaux already provides, these values are supported:

Error codes that come from the commands

  • 10000 + KernelExceptionType

    • Some commands throw this value from any KernelException that is thrown by the command executor. Indicates that the command failed to perform its operation, but the kernel already knows about it.

      • Example: If KernelExceptionType.Config is thrown from the command executor, and the command knows how to return this exception as an error code, such as using KernelExceptionTools.GetErrorCode(), then it'll return the sum of 10000 + 7, which is 10007.

Command-specific error codes

  • 1

    • Indicates that the command answered n to the confirmation (FTP and SFTP's del command)

  • 2

    • Indicates that either the real or the imaginary number is not valid (imaginary command)

  • 3

    • Indicates that the unit type is not found (unitconv command)

  • 4

    • Indicates that the hashes don't match (verify command)

  • 5

    • Indicates that the version code can't be formed (version command)

    • Indicates that the action taken is invalid (todo command)

  • 6

    • Indicates that the version code can't be formed (platform command)

  • 7

    • Indicates that the line endings converter can't convert binary files (convertlineendings command)

  • 8

    • Indicates that the note number is not numeric (removenote command)

  • 9

    • Indicates that the repository has been modified (checkout command)

  • 10

    • Indicates that the branch doesn't exist (checkout command)

  • 11

    • Indicates that the repository has been modified (fetch command)

  • 12

    • Indicates that the remote doesn't exist (fetch command)

  • 13

    • Indicates that there are no remotes to pull updates from (fetch command)

  • 14

    • Indicates that you need to identify yourself (pull command)

  • 15

    • Indicates that you need to identify yourself (maketag and commit command)

  • 16

    • Indicates that the culture is not found (altdate command)

  • 17

    • Indicates that there is no such lyric file (playlyric command)

  • 18

    • Indicates that the number of times is invalid (repeat command)

  • 19

    • Indicates that repeat can't repeat itself (repeat command)

  • 20

    • Indicates that the number of columns is invalid (wraptext command)

  • 21

    • Indicates that the extension handler is not registered (getdefaultexthandler command)

  • 22

    • Indicates that the extension handler is not registered (getexthandlers command)

  • 23

    • Indicates that the extension is not registered (setexthandler command)

  • 24

    • Indicates that the extension implementer is not registered (setexthandler command)

  • 25

    • Indicates that the port number is invalid (netfminfo command)

  • 26

    • Indicates that the number of seconds or the drink name is invalid (caffeine command)

  • 27

    • Indicates that there is no such lyric file (lyriclines command)

  • 28

    • Indicates that there is no config or key (getconfigvalue, setconfigvalue, and lsconfigvalues command)

  • 29

    • Indicates that the music file is not found (playsound command)

  • 30

    • Indicates that the MPG123 library has timed out (playsound command)

    • Indicates that the music file is not specified (musicplayer command)

  • 31

    • Indicates that the music file is not found (musicplayer command)

  • 32

    • Indicates that there are no caffeine alerts to abort (caffeine command)

  • 33

    • Indicates that this command is not supported on Windows (showmainbuffer command)

  • 34

    • Indicates that the dock is not found (dock command)

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