logical_names
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+ | ===== Logical Names ===== | ||
+ | |||
+ | The concept of a "// | ||
+ | |||
+ | ==== Introduction ==== | ||
+ | |||
+ | In its simplest form and meaning, a **logical name** is nothing more than an alternate or alias name-string for another string-value. | ||
+ | |||
+ | $ show logical sys$announce | ||
+ | " | ||
+ | |||
+ | From this, we see several things: | ||
+ | |||
+ | * There is a logical name whose // | ||
+ | * This logical name has an // | ||
+ | * This logical name is contained in a particular VMS //logical name table//, specifically the " | ||
+ | |||
+ | The value string of this logical name SYS$ANNOUNCE is displayed whenever a user logs-into the system successfully -- that's just how it's used (a conventional use). It might be convenient or useful for a sysadmin to change this logical name's value, like this: | ||
+ | |||
+ | $ DEFINE /SYSTEM /EXEC SYS$ANNOUNCE " Welcome to OpenVMS v8.4 on system PLUTO" | ||
+ | %DCL-I-SUPERSEDE, | ||
+ | |||
+ | The information message '' | ||
+ | |||
+ | You don't have to be the sysadmin to use logical names -- indeed, there are lots of ways for ordinary VMS users to make use of logical names in their own login sessions. | ||
+ | |||
+ | ==== Typical Uses for Logicals ==== | ||
+ | |||
+ | Three DCL commands suffice for creating and using your own logical names (or "// | ||
+ | |||
+ | * '' | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | See the HELP entries for each of these commands (an archaic, deprecated '' | ||
+ | |||
+ | Logical names are recognized and interpreted automatically in DCL commands (and other context) wherever they occur. | ||
+ | |||
+ | The **most common use** for logical names is as " | ||
+ | |||
+ | $ DEFINE com DISK$USERS: | ||
+ | $ DEFINE logs DISK$USERS: | ||
+ | $ | ||
+ | $ ! example of use: | ||
+ | $ SUBMIT com: | ||
+ | |||
+ | $ DEFINE /NOLOG /JOB SYS$SCRATCH DISK$USERS: | ||
+ | $ DIRECTORY /SIZE /DATE sys$scratch: | ||
+ | %DIRECT-W-NOFILES, | ||
+ | $ ! empty so far... | ||
+ | |||
+ | $ DEFINE sys$print HPLJ4000 | ||
+ | $ PRINT logs: | ||
+ | |||
+ | Logical names are tremendously versatile and useful, and any users' efforts to understand and exploit logicals is worth it. This intro just scratches the surface. | ||
logical_names.txt · Last modified: 2018/10/03 21:57 by lricker