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*Conan The Librarian (sorry for the slow response - running on an old VAX)
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VMS Help @ *Conan The Librarian (sorry for the slow response - running on an old VAX) |
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Executes a command procedure or requests the command interpreter
to read subsequent command input from a specific file or device.
Format
@ filespec [parameter[,...]]
| 1 - 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:
o 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.
o If the first parameter begins with a slash (/), you must
enclose the parameter in quotation marks (" ").
o 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:
$ WRITE SYS$OUTPUT P1
Enter the following at the DCL prompt ($):
$ @TEST "Never say ""quit"""
When the procedure TEST.COM executes, the parameter P1 is
equated to the following string:
Never say "quit"
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:
$ @TEST abc"def"ghi
When the procedure TEST.COM executes, the parameter P1 is
equated to the following string:
ABC"def"GHI
To use a symbol as a parameter, enclose the symbol in single
quotation marks (` ') to force symbol substitution. For example:
$ NAME = "JOHNSON"
$ @INFO 'NAME'
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.
| 2 - Qualifier |
2.1 - /OUTPUT
/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$OUTPUT filespec
When the procedure exits, SYS$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.
| 3 - 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
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
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
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
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
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
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
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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