Argument list processing


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Argument list processing
If the first argument (argument 0) to the shell is `-' then it is a
login shell. A login shell can be also specified by invoking the shell with
the -l flag as the only argument.

The rest of the flag arguments are interpreted as follows:



-b

Forces a ``break'' from option processing, causing any
further shell arguments to be treated as non-option arguments. The remaining
arguments will not be interpreted as shell options. This may be used to pass
options to a shell script without confusion or possible subterfuge. The shell
will not run a set-user ID script without this option.


-c

Commands are read from the following argument (which must be present, and
must be a single argument),
stored in the command shell variable for reference, and executed.
Any remaining arguments are placed in the argv shell variable.


-d

The shell loads the directory stack from ~/.cshdirs as described under
Startup and shutdown, whether or not it is a login shell. (+)


-Dname[=value]

Sets the environment variable name to value. (Domain/OS only) (+)


-e

The shell exits if any invoked command terminates abnormally or
yields a non-zero exit status.


-f

The shell ignores ~/.tcshrc, and thus starts faster.


-F

The shell uses fork(2) instead of vfork(2) to spawn processes. (Convex/OS only) (+)


-i

The shell is interactive and prompts for its top-level input, even if
it appears to not be a terminal. Shells are interactive without this option if
their inputs and outputs are terminals.


-l

The shell is a login shell. Only applicable if -l is the only
flag specified.


-m

The shell loads ~/.tcshrc even if it does not belong to the effective
user. Newer versions of su(1) can pass -m to the shell. (+)


-n

The shell parses commands but does not execute them.
This aids in debugging shell scripts.


-q

The shell accepts SIGQUIT (see Signal handling) and behaves when
it is used under a debugger. Job control is disabled. (u)


-s

Command input is taken from the standard input.


-t

The shell reads and executes a single line of input. A `\' may be used to
escape the newline at the end of this line and continue onto another line.


-v

Sets the verbose shell variable, so that
command input is echoed after history substitution.


-x

Sets the echo shell variable, so that commands are echoed
immediately before execution.


-V

Sets the verbose shell variable even before executing ~/.tcshrc.


-X

Is to -x as -V is to -v.


After processing of flag arguments, if arguments remain but none of the
-c, -i, -s, or -t options were given, the first
argument is taken as the name of a file of commands, or ``script'', to
be executed. The shell opens this file and saves its name for possible
resubstitution by `$0'. Since many systems use either the standard
version 6 or version 7 shells whose shell scripts are not compatible
with this shell, the shell uses such a `standard' shell to execute a script
whose first character is not a `#', i.e. which does not start with a
comment.

Remaining arguments are placed in the argv shell variable.

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