DCL Tips
*Conan The Librarian (sorry for the slow response - running on an old VAX)
|
VMS Help DCL Tips *Conan The Librarian (sorry for the slow response - running on an old VAX) |
|
This help category contains information on syntax used when
specifying values for various DCL commands and expressions.
| 1 - Date Time |
When a command requires a qualifier that specifies a date/time
value, the value is either an absolute time, delta time, or a
combination of the two.
1.1 - Absolute
Absolute time includes a specific date or time of day. An
absolute date/time has one of the following formats:
dd-mmm-yyyy
hh:mm:ss.cc
dd-mmm-yyyy:hh:mm:ss.cc
"dd-mmm-yyyy hh:mm:ss.cc"
TODAY
YESTERDAY
TOMORROW
You can omit any of the trailing fields in the date or time. You
can omit any of the fields in the middle of the format as long as
you specify the punctuation marks, for example, "-mmm-yyyy hh".
1.2 - Combination
Combination time consists of an absolute time value plus or
minus a delta time value. Combination time can use either of
the following formats:
"[absolute time][+delta time]"
[absolute time][-delta time]
You can omit the absolute time value. If you do, the delta
time is offset from the current date and time. Whenever a plus
sign (+) precedes the delta time value, enclose the entire time
specification in quotation marks.
1.3 - Delta
Delta time is an offset from the current time to a time in the
future. Delta time has the following format:
"+[dddd-][hh:mm:ss.cc]"
You can truncate delta time after the hour field. You can also
omit any of the fields after the hour field format as long as you
specify the punctuation marks.
1.4 - Examples
1.$ PRINT/AFTER=11-DEC-1996:13 NOVEMBER_REPORT.LIS
$ PRINT/AFTER="11-DEC-1996 13" NOVEMBER_REPORT.LIS
Both examples specify in absolute time that the file
NOVEMBER_REPORT.LIS will be printed on December 11, at 1:00 p.m.
2.$ PRINT/AFTER=11-DEC-1996:13-1:00 NOVEMBER_REPORT.LIS
This example specifies in combination time that the file will
be printed at 12:00 p.m. on December 11, 1996.
3.$ PRINT/AFTER="+3" NOVEMBER_REPORT.LIS
This example specifies in delta time that the file will be
printed 3 hours from the present time.
| 2 - Expression |
When you specify an expression, DCL evaluates values based on
the operations specified in the expression. The values can be
integers or character strings.
Some expression operators are conventional mathematical
symbols, for example, plus sign (+). Others specify logical
and comparison operations, and consist of letters preceded and
followed by periods; for example, .EQS. Operators are assigned a
precedence that determines their order of evaluation. You can use
parentheses to override this order.
For additional information on specifying expressions, refer to
the OpenVMS User's Manual.
2.1 - Arithmetic
The operator with the highest precedence in an expression is
evaluated first. Following this, the next highest operator is
evaluated, and so on. Operators with the same precedence are
evaluated from left to right, as they appear in the expression.
Operator Precedence Description
* 6 Arithmetic multiplication
/ 6 Arithmetic division
+ 5 Arithmetic plus
- 5 Arithmetic minus
.EQ. 4 Arithmetic equal
.GE. 4 Arithmetic greater than or equal
.GT. 4 Arithmetic greater than
.LE. 4 Arithmetic less than or equal
.LT. 4 Arithmetic less than
.NE. 4 Arithmetic not equal
.NOT. 3 Logical NOT
.AND. 2 Logical AND
.OR. 1 Logical OR
2.2 - String
The operator with the highest precedence in an expression is
evaluated first. Following this, the next highest operator
precedence is evaluated, and so on. Operators with the same
precedence are evaluated from left to right, as they appear in
the expression.
Operator Precedence Description
+ 5 String concatenation
- 5 String reduction
.EQS. 4 String equal
.GES. 4 String greater than or equal
.GTS. 4 String greater than
.LES. 4 String less than or equal
.LTS. 4 String less than
.NES. 4 String not equal
| 3 - Filespec |
File specifications provide the system with the information
necessary to identify a unique file or device. File
specifications have the following format:
node::device:[directory]filename.type;version
The punctuation marks are required to separate the fields of the
file specification. These fields are:
node Network node name
device Device name
directory Directory name
filename File name
type File type
version File version number
3.1 - Example
$ COPY GREEN::DISK1:[JONES]BUSINESS_REPORT.TXT;4
_To: BUSINESS_REPORT.TXT
This example shows how a file is specified when using the COPY
command to copy a file to the current directory from another
user's directory on another node.
| 4 - Integer |
DCL treats all numeric values as integers. If you do not specify
an explicit radix, numeric values are interpreted as decimal. You
may specify an explicit radix as follows:
%D1000 decimal radix
%O1357 octal radix
%X12AF hexadecimal radix
No blanks are allowed between the radix symbol and the number.
For additional information on specifying integers, refer to the
OpenVMS User's Manual.
| 5 - Privilege |
Your set of privileges affects the system resources and system
functions you are allowed to use. The following table describes
privileges and their functions:
ACNT Create a process for which no accounting is performed.
ALL Allow all privileges.
ALLSPOOL Allocate spooled devices.
ALTPRI Increase the base execution priority for any process.
BUGCHK Make bugcheck error log entries.
BYPASS Access resources without regard to UIC protection.
CMEXEC Change mode to Executive.
CMKRNL Change mode to Kernel.
DETACH Create detached processes.
DIAGNOSE Issue diagnostic I/O requests.
EXQUOTA Exceed resource quotas.
GROUP Control execution of other processes in the same group.
GRPNAM Enter names in the group logical name table.
GRPPRV Allow access to files in the group and system
categories.
LOG_IO Issue logical I/O requests.
MOUNT Issue mount volume I/O requests.
NETMBX Create a network device.
OPER Perform system operator functions.
PFNMAP Create or delete sections mapped by page frame.
PHY_IO Issue physical I/O requests.
PRMCEB Create permanent common event flag clusters.
PRMGBL Create permanent global clusters.
PRMMBX Create permanent mailbox devices.
PSWAPM Change process swap mode.
READALL Bypass restrictions otherwise preventing process from
reading a file.
SECURITY Perform security-related functions.
SETPRV Grant a process any privilege.
SHARE Assign a channel to a device.
SHMEM Create or delete data structures in shared memory.
SYSGBL Create system global sections.
SYSLCK Request locks on system resources.
SYSNAM Enter names in the system logical name table.
SYSPRV Access resources as if the process has a system UIC.
TMPMBX Create temporary mailbox devices.
VOLPRO Override protection on a volume.
WORLD Control the execution of any process on the system.
5.1 - Example
$ SHOW PROCESS/PRIVILEGES
11-DEC-1996 10:15:43.79 User: J_BROWN Process ID: 123000AB1
Node: FABLES Process name: "J_BROWN"
Process privileges:
TMPMBX may create temporary mailbox
NETMBX may create network device
In this example, the SHOW PROCESS command is used to display
privileges for the current process. The user J_BROWN has TMPMBX
and NETMBX privileges.
| 6 - Protection |
Volume and file protection is specified as follows:
(SYSTEM:RWED,OWNER:RWED,GROUP:RWED,WORLD:RWED)
There are four categories of protection: one for system
processes, one for the owner of the file, one for other members
of the owner's group, and one for members of other groups. For
each category, any combination of four different types of access
may be specified:
R read access
W write access
E execute access (for execution of images)
D delete access
If you want to deny all access to a category, you must specify
the category name without a colon, for example:
/PROTECTION=(OWNER:RWE,GROUP,WORLD)
For complete information on setting protections, see the OpenVMS
Guide to System Security.
6.1 - Example
$ DIRECTORY/PROTECTION JUNE_REPORT.LIS
Directory DISK1:[J_BROWN]
JUNE_REPORT.LIS;1 (RWED,RWED,RE,)
In this example, the user entered the DIRECTORY/PROTECTION
command to see what the protection is for the file JUNE_
REPORT.LIS. Users in the system and owner categories have read,
write, execute, and delete access, users in the group category
have read and execute access, and users in the world category
have no access to this file.
| 7 - String |
A character string value is represented as a sequence of
characters enclosed in quotation marks (" "). A quotation mark
in a character string must be represented by two quotation marks.
In certain contexts, the quotation marks are optional.
For additional information on specifying character strings, see
the OpenVMS User's Manual.
| 8 - Symbol |
A symbol is an entity that has a name and a value. The name can
consist of letters, digits, underscores (_) and dollar sign
($). It can be composed of up to 255 characters. The value of
the symbol can be a 32-bit integer or a string with zero to 255
characters.
Symbols are defined in DCL with the assignment statement. This is
described under the Help topic SYMBOL_ASSIGN.
| 9 - UIC |
A UIC is a user identification code that can be in either numeric
or named format. When a DCL command requires a UIC specification,
you can specify either format. However, the system converts all
UICs to numeric format when determining a user's access to a data
resource.
A UIC in numeric format consists of a group number and a member
number in the format:
[group,member]
where:
group is an octal number in the range 0 through 37776
representing the group number.
member is an octal number in the range 0 through 37776
representing the member number.
The square brackets are required in the UIC specification. You
can also omit leading zeros when specifying group and member
numbers.
A UIC in named format consists of a member identifier and
optionally, a group identifier, as shown in either of the
following:
[member]
[group,member]
The group and member identifiers can each contain up to 31
alphanumeric characters and must contain at least one alphabetic
character. The names can include the characters A through Z,
dollar signs ($) underscores (_), and the numbers 0 through 9.
The brackets are required in the UIC specification.
The member number is unique for each user on the system, and is
equivalent to the user's numeric UIC (including both the group
and the member numbers). The group identifier is equivalent to
only the group portion of the UIC.
For additional information on specifying UICs, refer to the
OpenVMS Guide to System Security.
|
|
