Predefined Process-Wide Variables

Name	Default	Use
$		A synonym for the processid variable.
bsdhistory	0	By default, “!!” is the immediately preceding command and “!-1” is the one before that. Setting bsdhistory = 1 makes them the same.
cdpath	null	Same as the CDPATH environmental variable, broken into words.
cshtitle		Same as the CSHTITLE environmental variable.
escapesym	^	Character to be interpreted as a literal escape character.
histchars	!%	Characters which introduce long-form and short-form history references, respectively.
home		Same as the HOME environmental variable.
NTVersion		Obsolete name for the WinBuild variable.
OperatingSystem		Name of the operating system on which the shell is running. Possible values are “Windows NT” and “Windows 9x”.
path		Same as the PATH environmental variable, broken into words.
processid		The unique process ID assigned by the Windows kernel to this copy of the C shell.
prompt1	$@ $CDISK%	Same as PROMPT1 environmental variable.
prompt2	$@ $CDISK?	Same as PROMPT2 environmental variable.
savehist	0	Save the history contents into history.csh in the home directory.
shell		Same as SHELL environmental variable.
WinBuild		Build number of the Windows NT or Windows 9x system on which the shell is running, e.g., 2600 for Windows XP.
WinVersion		Version number of the Windows API on which the shell is running, e.g., 5.1 for Windows XP.

Any user-defined variables (with the exception of the parameter names of a procedure or those variables explicitly defined as local) are shared globally by all threads.