## 8.2. Invoking the Shell

A shell command interpreter can be invoked as follows:

>     csh  [options]  [arguments]
>     tcsh  [options]  [arguments]

csh and tcsh use syntax resembling C and execute commands from a terminal or a file. Options -n, -v, and -x are useful when debugging scripts.

### 8.2.1. Options

-b

  Allow the remaining command-line options to be interpreted as options to a specified command, rather than as options to csh itself.

-c

  Execute command specified following the argument.

-d

  Load directory stack from ~/.cshdirs even if not a login shell. (tcsh)

-e

  Exit if a command produces errors.

-f

  Fast startup; start without executing .cshrc or .tcshrc.

-i

  Invoke interactive shell (prompt for input).

-l

  Login shell (must be the only option specified).

-m

  Load ~/.tcshrc even if effective user is not the owner of the file. (tcsh)

-n

  Parse commands, but do not execute.

-s

  Read commands from the standard input.

-t

  Exit after executing one command.

-v

  Display commands before executing them; expand history substitutions, but not other substitutions (e.g., filename, variable, and command). Same as setting verbose.

-V

  Same as -v, but also display .cshrc.

-x

  Display commands before executing them, but expand all substitutions. Same as setting echo.

-X

  Same as -x, but also display .cshrc.

### 8.2.2. Arguments

Arguments are assigned, in order, to the positional parameters $1, $2, and so on. If the first argument is an executable script, commands are read from it, and remaining arguments are assigned to $1, $2, and so forth.

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