The UNIX Bourne Shell Language

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Version 2.32

The UNIX Bourne Shell Language

Overview

What Is Bourne Shell?: The Bourne shell (/bin/sh) is the original UNIX shell. It is basic and slow. Most systems provided an extended version that supports functions.
Portability: There are at least two flavours of Bourne shell; with and without functions. The simplest is portable to probably all UNIX systems; the extended Bourne shell to most UNIX systems (I know only one that does not provide it: NeXT.
Pros and Cons: Pros: Most standard shell. Cons: functionally poor; like all shells, slower than Awk or Perl or C.
How To Get It: Should be installed on your UNIX system.

Working With The UNIX Bourne Shell

Schema: lrschema.sh.
Program model: executable UNIX script.
Good for: complex scripts; portable to GNU systems.
Files used/made: own work in myprog.mod; generates a script called myprog.
Module functions: module_function_name ()
Private functions: private_function_name (). Since there is no way to distinguish module functions from private functions, the schema turns-off idle module checking.
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                      # Empty module needs 'return'
}

private_function_name ()
{
    the_next_event=$ok_event
    raise_exception $error_event
}