HP OpenVMS DCL Dictionary
@ (Execute Procedure)
Executes a command procedure or requests the command interpreter to
read subsequent command input from a specific file or device.
Format
@ filespec [parameter[,...]]
Parameters
filespec
Specifies either the input device or the file for the preceding
command, or the command procedure to be executed. The default file type
is .COM. The asterisk (*) and the percent sign (%) wildcard characters
are not allowed in the file specification.
parameter[,...]
Specifies from one to eight optional parameters to pass to the command
procedure. The symbols (P1, P2, ... P8) are assigned character string
values in the order of entry. The symbols are local to the specified
command procedure. Separate each parameter with one or more blanks. Use
two consecutive quotation marks ("") to specify a null parameter. You
can specify a parameter with a character string value containing
alphanumeric or special characters, with the following restrictions:
- The command interpreter converts alphabetic characters to uppercase
and uses blanks to delimit each parameter. To pass a parameter that
contains embedded blanks or literal lowercase letters, place the
parameter in quotation marks.
- If the first parameter begins with a slash (/), you must enclose
the parameter in quotation marks (" ").
- To pass a parameter that contains literal quotation marks and
spaces, enclose the entire string in quotation marks and use two
consecutive quotation marks within the string. For example, the command
procedure TEST.COM contains the following line:
Enter the following at the DCL prompt ($):
$ @TEST "Never say ""quit"""
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When the procedure TEST.COM executes, the parameter P1 is equated
to the following string:
If a string contains quotation marks and does not contain spaces,
the quotation marks are preserved in the string and the letters within
the quotation marks remain in lowercase. For example, enter the
following at the DCL prompt:
When the procedure TEST.COM executes, the parameter P1 is equated
to the following string:
To use a symbol as a parameter, enclose the symbol in single quotation
marks (` ') to force symbol substitution. For example:
$ NAME = "JOHNSON"
$ @INFO 'NAME'
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The single quotation marks cause the value "JOHNSON" to be
substituted for the symbol NAME. Therefore, the parameter
"JOHNSON" is passed as P1 to INFO.COM.
Description
Use the @ command to execute a command procedure that contains the
following:
- DCL command lines or data, or both
- Qualifiers or parameters, or both, for a specific command line
To execute a command procedure containing commands or data, or both,
place the @ command at the beginning of a command line and then specify
the name of the command procedure file. The command procedure can
contain DCL commands and input data for a command or program that is
currently executing. All DCL commands in a command procedure must begin
with a dollar sign ($). If a command is continued with a hyphen (-),
the subsequent lines must not begin with a dollar sign.
Any line in a command procedure that does not contain a dollar sign in
the first character position (and is not a continuation line) is
treated as input data for the command or program that is currently
executing. The DECK command allows you to specify that data contains
dollar signs in record position one.
A command procedure can also contain the @ command to execute another
command procedure. The maximum command level you can achieve by nesting
command procedures is 16, including the top-level command procedure.
Command procedures can also be queued for processing as batch jobs,
either by using the SUBMIT command or by placing a deck of cards
containing the command procedure in the system card reader.
To execute a command procedure that contains qualifiers or parameters,
or both, for a specific command line, place the @ command where the
qualifiers or parameters normally would be in the command line. Then
specify the name of the command procedure file containing the
qualifiers or parameters.
If the command procedure file begins with parameters for the command,
the @ command must be preceded by a space. For example:
$ CREATE TEST.COM
TIME
[Ctrl/Z]
$ SHOW @TEST
14-SEP-2001 17:20:26
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If the file begins with qualifiers for the command, do not
precede the @ command with a space. For example:
$ CREATE TEST_2.COM
/SIZE
[Ctrl/Z]
$ DIR@TEST_2
Directory WORK$:[SCHEDULE]
JANUARY.TXT;8 14-DEC-2001 15:47:45.57
FEBRUARY.TXT;7 14-DEC-2001 15:43:16.20
MARCH.TXT;6 14-DEC-2001 11:11:45.74
.
.
.
Total of 11 files.
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If the file contains parameters or qualifiers, or both, do not
begin the lines in the file with dollar signs. Any additional data on
the command line following @filespec is treated as parameters for the
procedure.
Qualifier
/OUTPUT=filespec
Specifies the name of the file to which the command procedure output is
written. By default, the output is written to the current SYS$OUTPUT
device. The default output file type is .LIS. The asterisk (*) and the
percent sign (%) wildcard characters are not allowed in the output file
specification. System responses and error messages are written to
SYS$COMMAND as well as to the specified file. The /OUTPUT qualifier
must immediately follow the file specification of the command
procedure; otherwise, the qualifier is interpreted as a parameter to
pass to the command procedure.
You can also redefine SYS$OUTPUT to redirect the output from a command
procedure. If you place the following command as the first line in a
command procedure, output will be directed to the file you specify:
$ DEFINE SYS$OUTPUT filespec
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When the procedure exits, SYS$OUTPUT will be restored to its original
equivalence string. This produces the same result as using the /OUTPUT
qualifier when you execute the command procedure.
Examples
| #1 |
$ CREATE DOFOR.COM
$ ON WARNING THEN EXIT
$ IF P1.EQS."" THEN INQUIRE P1 FILE
$ FORTRAN/LIST 'P1'
$ LINK 'P1'
$ RUN 'P1'
$ PRINT 'P1'
[Ctrl/Z]
$ @DOFOR AVERAGE
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This example shows a command procedure, named DOFOR.COM, that executes
the FORTRAN, LINK, and RUN commands to compile, link, and execute a
program. The ON command requests that the procedure not continue if any
of the commands result in warnings or errors.
When you execute DOFOR.COM, you can pass the file specification of the
FORTRAN program as the parameter P1. If you do not specify a value for
P1 when you execute the procedure, the INQUIRE command issues a
prompting message to the terminal and equates what you enter with the
symbol P1. In this example, the file name AVERAGE is assigned to P1.
The file type is not included because the commands FORTRAN, LINK, RUN,
and PRINT provide default file types.
| #2 |
$ @MASTER/OUTPUT=MASTER.LOG
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This command executes a procedure named MASTER.COM; all output is
written to the file MASTER.LOG.
| #3 |
$ CREATE FILES.COM
*.FOR, *.OBJ
[Ctrl/Z]
$ DIRECTORY @FILES
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This example shows a command procedure, FILES.COM, that contains
parameters for a DCL command line. The entire file is treated by DCL as
command input. You can execute this procedure after the DIRECTORY
command to get a listing of all FORTRAN source and object files in your
current default directory.
| #4 |
$ CREATE QUALIFIERS.COM
/DEBUG/SYMBOL_TABLE/MAP/FULL/CROSS_REFERENCE
[Ctrl/Z]
$ LINK SYNAPSE@QUALIFIERS
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This example shows a command procedure, QUALIFIERS.COM, that contains
qualifiers for the LINK command. When you enter the LINK command,
specify the command procedure immediately after the file specification
of the file you are linking. Do not type a space between the file
specification and the @ command.
| #5 |
$ CREATE SUBPROCES.COM
$ RUN 'P1' -
/BUFFER_LIMIT=1024 -
/FILE_LIMIT=4 -
/PAGE_FILES=256 -
/QUEUE_LIMIT=2 -
/SUBPROCESS_LIMIT=2 -
'P2' 'P3' 'P4' 'P5' 'P6' 'P7' 'P8'
[Ctrl/Z]
$ @SUBPROCES LIBRA /PROCESS_NAME=LIBRA
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This example shows a command procedure named SUBPROCES.COM. This
procedure issues the RUN command to create a subprocess to execute an
image and also contains qualifiers defining quotas for subprocess
creation. The name of the image to be run is passed as the parameter
P1. Parameters P2 to P8 can be used to specify additional qualifiers.
In this example, the file name LIBRA is equated to P1; it is the name
of an image to execute in the subprocess. The qualifier
/PROCESS_NAME=LIBRA is equated to P2; it is an additional qualifier for
the RUN command.
| #6 |
$ CREATE EDOC.COM
$ ASSIGN SYS$COMMAND: SYS$INPUT
$ NEXT:
$ INQUIRE NAME "File name"
$ IF NAME.EQS."" THEN EXIT
$ EDIT/TPU 'NAME'.DOC
$ GOTO NEXT
[Ctrl/Z]
$ @EDOC
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This procedure, named EDOC.COM, invokes the EVE editor. When an edit
session is terminated, the procedure loops to the label NEXT. Each time
through the loop, the procedure requests another file name for the
editor and supplies the default file type .DOC. When a null line is
entered in response to the INQUIRE command, the procedure terminates
with the EXIT command.
The ASSIGN command changes the equivalence name of SYS$INPUT for the
duration of the procedure. This change allows the EVE editor to read
input data from the terminal, rather than from the command procedure
file (the default input data stream if SYS$INPUT had not been changed).
When the command procedure exits, SYS$INPUT is reassigned to its
original value.
| #7 |
! PEOPLE.DAT
! A set of data with embedded key qualifiers for the SORT command.
!
! Usage: SORT@PEOPLE.DAT
!
/KEY=(POS:10,SIZE:10) sys$input people.out
Fred Flintstone 555-1234
Barney Rubble 555-2244
Wilma Flintstone 555-1234
Betty Rubble 555-2244
George Slate 555-8911
Dino Dinosaur 555-1234
$!
$ purge people.out
$ type people.out
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Creates a sorted list of people in file PEOPLE.OUT and displays it.
This demonstrates when using "@" in the middle of a DCL command, DCL
redirects the entire file as command input.
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