The UNIX C Shell Language

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Version 2.32

The UNIX C Shell Language

Overview

What Is C Shell?: The C shell (/bin/csh) is a UNIX shell 'for C programmers'.
Portability: The C shell is very standard across UNIX boxes, as far as I know.
Pros and Cons: Pros: standard. Your scripts will run on most if not all UNIX boxes. Looks a bit like C. Cons: limited and out-dated. No functions. Looks a bit like C.
How To Get It: Should be part of your UNIX system.

Working With The UNIX C Shell

Schema: lrschema.c.
Program model: executable UNIX script.
Good for: complex scripts.
Files used/made: own work in myprog.mod; generates script called myprog.
Module functions: module_function_name: #
Private functions: private_function_name:
Naming style: any except -style=cobol.
Limits: 254 modules, 254 events, 1000 states. The schema checks at generate-time that the dialog does not exceed these limits. All tables are defined dynamically, at runtime.
Development cycle: run lr after you change the dialog or .mod file. When you add a new module, run lr, then edit the .mod file, then run lr again. Don't change the generated script except for hacking - you'll lose your changes.

Example of code

Code fragments:

#################   MODULE FUNCTION NAME   #################

module_function_name: #
    return                      # All modules end in 'return'

private_function_name:          # Actually, not possible
    set the_next_event=$ok_event
    raise_exception $error_event

The C shell has no functions (unless I missed something), so I use labelled blocks of code. Each such block must end with 'return'. The schema defines this alias to do a goto back to the dialog engine code. Frankly, I can't understand who would write or use this shell. Get Perl, and use that instead. Flames welcome. Nuff sed.