The C shell maintains a list of special variables that can be read by
the user, but not written to or changed explicitly.
One of these was examined in the section on parameters,
$argv[n] which returned the value of the
of the shell command line.
Table 4.4 contains all of the special readonly
variables use in the C shell:
Table 4.4: Special read-only variables used in the C shell.
For example, to check whether
noclobber is set, one could enter
% echo $?noclobber 1
which would indicate that
noclobber is indeed set.
The usefulness of these variables will become apparent in the shell