EXIT - CMD

Overview

The EXIT command in Windows Command Prompt (CMD) is used to terminate a script or the command shell itself. It effectively closes the current CMD session or ends script execution when used within batch scripts. This command is useful for controlling the flow of batch files and for cleanly exiting from command prompt sessions after executing a sequence of commands.

Syntax

The basic syntax for the EXIT command is:

EXIT [/B] [exitCode]

/B : This optional parameter specifies that the command shell should exit only from the current batch script rather than closing the entire command prompt session.
exitCode : An optional integer that represents the exit code returned by the CMD session or script. This is particularly useful for determining the outcome of script executions in automated tasks.

Options/Flags

/B: Exits the current batch script instead of exiting the command prompt. This is useful in scenarios where you want to stop executing a script due to a conditional check without closing the entire CMD session.
exitCode: Specifies an exit code to be returned by the script or CMD session. By default, if no exit code is specified, the command returns the exit code from the last executed command. This can be utilized to indicate success (typically 0) or error (any non-zero value) to other processes or scripts that might rely on this script.

Examples

Simple Exit:
Exiting the command prompt:
```
EXIT
```
This command will close the CMD window or session.
Exit from a Batch Script:
```
IF %ERRORLEVEL% NEQ 0 EXIT /B 1
```
This command checks if the last executed command resulted in an error (ERRORLEVEL not equal to 0) and exits the script with an exit code of 1 without closing the entire CMD session.
Using Exit Codes:
```
EXIT 2
```
This will terminate the command prompt session and return an exit code of 2. This can be used by other programs to determine that an error occurred.

Common Issues

Ignoring exit codes: Users often forget to check or specify exit codes in scripts, which can lead to misleading interpretations of the success or failure of scripts.
Confusion with /B switch: The /B switch should be used carefully, as it only exits the batch script and not the CMD session. Misuse can lead to unexpected behaviors where the CMD window remains open.

Integration

The EXIT command can be combined with conditional statements to provide better control in script flows. For example:

@echo off
COPY file1.txt D:\backup\
IF %ERRORLEVEL% NEQ 0 (
    ECHO Failed to copy file!
    EXIT /B 1
) ELSE (
    ECHO File copied successfully.
    EXIT /B 0
)

This script attempts to copy a file and exits with different codes based on the success or failure of the copy command.

CMD: Initiates a new instance of the command interpreter.
START: Starts a separate window to run a specified program or command.

For more detailed information on the EXIT command and scripting in CMD, you can refer to Microsoft’s official documentation or resources like SS64.com and Microsoft Docs.