Writes the specified data as one record to an open file specified
by a logical name.
All qualifiers must precede all data item expressions.
Format
WRITE logical-name expression[,...]
1 – Parameters
logical-name
Specifies the logical name assigned to the output file. Use the
logical name assigned by the OPEN command. In interactive mode,
specify the process-permanent files identified by the logical
names SYS$INPUT, SYS$OUTPUT, SYS$ERROR, and SYS$COMMAND. (The
OPEN command assigns a logical name to a file and places the name
in the process logical name table.)
expression[,...]
Specifies data to be written as a single record to the output
file. You can specify data items using character string
expressions, which may be symbol names, character strings in
quotation marks (" "), literal numeric values, or a lexical
function. For more information on string expressions, see the
OpenVMS User's Manual.
You can specify a list of expressions separated by commas (,);
the command interpreter concatenates the items into one record
and writes the record to the output file.
The maximum size of any record that can be written is less than
1024 bytes, and the value of any symbol that is specified as part
of a record cannot exceed 255 characters; however, if you specify
the /SYMBOL qualifier, the maximum record size is 2048 bytes and
the value of a symbol can exceed 255 characters.
2 – Qualifiers
2.1 /ERROR
/ERROR=label
Transfers control on an I/O error to the location specified by
label (in a command procedure). If no error routine is specified
and an error occurs during the writing of the file, the current
ON condition action is taken. The /ERROR qualifier overrides any
ON condition action specified. If an error occurs and control
passes successfully to the target label, the reserved global
symbol $STATUS retains the error code.
2.2 /SYMBOL
Causes the expression to be interpreted and its expanded value
placed in a 2048-byte (instead of a 1024-byte) buffer before
the write operation is performed. If you specify multiple
expressions, their values are concatenated and placed in the
2048-byte buffer. Use the /SYMBOL qualifier to write a very large
record.
If you do not use the /SYMBOL qualifier, the entire command,
including the expression or expressions, is placed in a 1024-byte
buffer.
2.3 /UPDATE
Replaces the last record read with the record specified with the
expression parameter. You must be able to read and write to a
file to use the /UPDATE qualifier. Use the WRITE/UPDATE command
only after a READ command. The WRITE/UPDATE command modifies the
last record you have read.
With sequential files, you must replace a record with another
record of the same size when you use the WRITE/UPDATE command.
2.4 /WAIT
/WAIT (default)
/NOWAIT
If you specify /NOWAIT, the Put service to a mailbox device uses
the IO$M_NOW modifier, which causes the operation to complete
immediately instead of synchronizing with another reader of the
mailbox.
Currently this qualifier is supported on Alpha and Integrity
servers only.
3 – Examples
1.$ WRITE SYS$OUTPUT "Beginning second phase of tests"
The WRITE command writes a single line of text to the current
output device.
2.$ OPEN/APPEND OUTPUT_FILE TRNTO::DKA1:[PGM]PLAN.DAT
$ WRITE OUTPUT_FILE "BEGINNING PHASE 3"
In this example, the OPEN/APPEND command opens the file
PLAN.DAT at the remote node TRNTO and positions the pointer
at the end of the file. The WRITE command writes a record to
the end of the file PLAN.DAT.
3.$ OPEN/WRITE OUTPUT_FILE TESTFILE.DAT
$ INQUIRE ID "Assign Test-id Number"
$ WRITE/ERROR=WRITE_ERROR OUTPUT_FILE "Test-id is ",ID
$ WRITE/ERROR=WRITE_ERROR OUTPUT_FILE ""
$ !
$ WRITE_LOOP:
.
.
.
$ GOTO WRITE_LOOP
$ END_LOOP:
$ !
$ CLOSE OUTPUT_FILE
$ PRINT TESTFILE.DAT
$ EXIT
$ !
$ WRITE_ERROR:
$ WRITE SYS$OUTPUT "There was a WRITE error."
$ CLOSE OUTPUT_FILE
$ EXIT
In this example, the OPEN command opens the file TESTFILE.DAT;
the INQUIRE command requests an identification number to be
assigned to a particular run of the procedure. The number
entered is equated to the symbol ID. The WRITE commands write
a text line concatenated with the symbol name ID and a blank
line.
The lines between the label WRITE_LOOP and END_LOOP process
information and write additional data to the file. When the
processing is finished, control is transferred to the label
END_LOOP. The CLOSE and PRINT commands at this label close the
output file and queue a copy of the file to the system printer.
The label WRITE_ERROR is used as the target of the /ERROR
qualifier to the WRITE command; if an error occurs when a
record is being written, control is transferred to the label
WRITE_ERROR.
4.$ OPEN/APPEND MYFILE [LAMPERT]TESTING.DAT
$ WRITE/SYMBOL MYFILE A,B,C
This example assumes that the symbols A, B, and C have
already been defined. The OPEN/APPEND command opens the file
[LAMPERT]TESTING.DAT and positions the pointer at the end of
the file. The WRITE/SYMBOL command concatenates the values of
the symbols A, B, and C and writes this data to a new record at
the end of the file.