Windows 98 Command.com Startup Switches
Microsoft Windows 98 relies on COMMAND.COM as its
primary 16-bit command interpreter, handling the MS-DOS prompt and
processing initialization batch files. When diagnosing boot failures,
memory allocation issues, or batch script errors, several command-line
switches can be appended to the COMMAND.COM startup line to
alter its behavior. This guide details the specific diagnostic and
troubleshooting switches available for COMMAND.COM in
Windows 98 and explains how to apply them.
Step-by-Step Script Execution:
/Y
The /Y parameter is the primary diagnostic switch for
batch file execution in Windows 98. When combined with the
/C or /K parameters, /Y forces
COMMAND.COM to step through the specified batch program
line-by-line, prompting the user for confirmation before executing each
command.
If /Y is used alongside the /P (permanent)
switch during the boot sequence, it instructs the interpreter to prompt
before executing each line of AUTOEXEC.BAT. This allows
administrators to pinpoint the exact line or terminate-and-stay-resident
(TSR) program causing a crash or system lockup.
Critical Error Handling:
/F
The /F switch automatically answers "Fail" to any
system-level critical errors (such as the standard "Abort, Retry, Fail?"
prompt). In diagnostic scenarios, adding /F prevents the
command interpreter from hanging indefinitely when attempting to access
unreadable media or missing storage drives, allowing automated
diagnostic routines to continue or fail gracefully without user
intervention.
Memory-Resident Error
Messages: /MSG
The /MSG switch forces COMMAND.COM to store
all internal error messages in conventional memory rather than reading
them from the physical disk drive. This is useful when troubleshooting
systems with failing hard drives, corrupt system files, or systems
booting entirely from read-only media or floppy disks. The trade-off is
a slight increase in conventional memory usage.
Return Code Tracking:
/Z
In MS-DOS 7.1 (the underlying DOS version of Windows 98), the
undocumented /Z switch can be used for error-level
diagnostics. When enabled, COMMAND.COM displays the return
code (errorlevel) returned by external programs immediately after they
finish executing, eliminating the need to write separate batch scripts
checking IF ERRORLEVEL statements.
Expanding Environment Space:
/E:size
Running out of environment space often causes configuration variables
to truncate, resulting in silent failures during software
initialization. The /E switch sets the memory size
allocated for environment variables, where size can range
from 256 to 32,768 bytes. The default allocation is 256 bytes.
Increasing this value (e.g., /E:2048 or
/E:4096) resolves the common "Out of environment space"
error encountered during complex boot routines.
Preserving Debug Output:
/K
The /K switch executes a specified command or batch file
and leaves the command interpreter active. For diagnostics, this ensures
that the MS-DOS prompt window does not close automatically after
executing a troubleshooting script, allowing users to review generated
error logs, driver loading messages, and screen output.
Applying Diagnostic Switches
To apply these switches globally at boot time, modify the
SHELL directive inside CONFIG.SYS:
SHELL=C:\WINDOWS\COMMAND.COM C:\WINDOWS /P /E:2048 /YFor diagnostic testing within an active Windows 98 session, append the switches directly to the target field in the MS-DOS Prompt shortcut properties or execute them directly from the Run dialog box.