DIGITAL Command Language

An abbreviation of Digital Command Language, DCL had it's history in RSX-11 and RSTS/11 operating systems. However it took it's most powerful form in the OpenVMS operating system by Digital Equipment Corp.

A scripting language that was written when Fortran programming language was in heavy use, it supports the following data-types strings, integers, bit arrays, arrays, booleans but not floating point numbers. Access to OpenVMS System Services (kernel api) is through Lexical Functions, these perform the same as their compiled language counterparts and allow scripts to get System, Cluster, Device, Process, Printer, Batch Queue, File, Console Environment and Logical Names information. It includes if-then-else, for and do-while loops, access to all the RMS file types including stream, indexed, and sequential.

The Command Line parser is a library function (CLI$) that can be compiled into user applications and therefore gives a consistent command line interface for both Operating System supplied commands and User written commands. The Command line must start with a verb and is then followed by arguments and/or position indepdendant or position dependant qualifiers (switches in Unix speak). Most qualifiers are position independant, that is they can appear anywhere in the command line and only the first most significant part of the qualifier name is required (same for the verb). An example Operating System command may look like;

   set audit/alarm/enable=(authorization,breakin=all)
   show device/files $1$DGA1424:

The second show command could also be typed as

   sho dev $1$DGA1424:/fil