Difference between revisions of "Command procedure"
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| − | A '''command procedure''' is a file that holds a sequence of DCL commands to be executed by the system in sequence interactively or as a batch job - essentially a [[DCL]] script. Command procedure files have the [[File extension|extension]] of .COM. | + | A '''command procedure''' is a file that holds a sequence of DCL commands to be executed by the system in sequence interactively or as a batch job - essentially a [[DCL]] script. Command procedure files by convention have the [[File extension|extension]] of .COM. |
=Rules and conventions= | =Rules and conventions= | ||
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There are also certain conventions that it is recommended to follow to improve clarity and maintainability of the code: | There are also certain conventions that it is recommended to follow to improve clarity and maintainability of the code: | ||
| − | + | # Give your command procedure a name that indicates its purpose and use .COM as the file type. | |
| − | + | # Use complete names for commands and qualifiers. This will help to ensure that your command procedure is upwardly compatible to future releases of OpenVMS. | |
| − | + | # Start each command procedure with one or more [[Comment|comment]] lines, at least stating the purpose of the command procedure. | |
| − | + | # End the command procedure with an EXIT or STOP statement. | |
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=Example= | =Example= | ||
Latest revision as of 12:59, 23 March 2022
A command procedure is a file that holds a sequence of DCL commands to be executed by the system in sequence interactively or as a batch job - essentially a DCL script. Command procedure files by convention have the extension of .COM.
Rules and conventions
Command procedures in OpenVMS follow a set of rules; if they are broken, an error message is displayed and the command procedure may fail.
1. Every line in a command procedure that is not a data line has to begin with the dollar sign ($):
$ if f$mode() .nes. "INTERACTIVE" then exit
2. Comments begin with an exclamation point (!). Comment lines begin with a dollar sign AND an exclamation point ($!):
$ if count .eq. 5 !Last element $! Return to the previous level
There are also certain conventions that it is recommended to follow to improve clarity and maintainability of the code:
- Give your command procedure a name that indicates its purpose and use .COM as the file type.
- Use complete names for commands and qualifiers. This will help to ensure that your command procedure is upwardly compatible to future releases of OpenVMS.
- Start each command procedure with one or more comment lines, at least stating the purpose of the command procedure.
- End the command procedure with an EXIT or STOP statement.
Example
$! This command procedure displays a message based on the current day of the week. $ say := write sys$output $ day = f$cvtime(,,"WEEKDAY") $! show sym day $ say "Hooray, it's ''day'!"
