COMSPEC vs. _CMDSPEC

[Jay Sage]

I've noticed that there are two variables that seem to contain the same thing. Is there a difference? Are they used in different ways, or are they interchangeable?

 

[vefatica]

From the help:

_CMDSPEC returns the full pathname of the command processor.

I think COMSPEC is the same and may exist for CMD compatibility.

 

[Joe Caverly]

PS E:\utils> $env:comspec
C:\WINDOWS\system32\cmd.exe
PS E:\utils> tcc echo %_cmdspec
C:\Program Files\JPSoft\TCMD36\TCC.EXE
PS E:\utils>

_CMDSPEC is TCC specific,
that is,
it will only return TCC.EXE

Joe

 

[vefatica]

There may be a subtle (or not so subtle) difference. Traditionally, COMSPEC names the default command processor.

I vaguely remember a discussion, decades ago, about whether, in Windows, C's system() function honored COMSPEC. I don't recall the upshot of that discussion. Today it doesn't seem important.

 

[Joe Caverly]

I just started 4DOS,
and these are the results;

Not sure if I still have TCC installed in my Windows 98 system...

Joe

 

[Charles Dye]

COMSPEC is an environment variable. Lots of other programs — yea, even unto the days of MS-DOS — can read this environment variable. Some may even depend on it.

_CMDSPEC is an internal variable. External programs generally won't be able to access it.

 

[AnrDaemon]

COMSPEC is a command interpreter that other programs will use to execute commands.
I have a few wrappers written in TCC, which had to redefine ComSpec back to CMD to make wrapped programs behave.