The CLOSE command breaks the connection between a process and a device.
The format of the CLOSE command is:
C[LOSE][:tvexpr] expr[:(keyword[=expr][:...])][,...]
The optional truth-valued expression immediately following the command is a command postconditional that controls whether or not GT.M executes the command.
The required expression specifies the device to CLOSE.
The optional keywords specify deviceparameters that control device behavior; some deviceparameters take arguments delimited by an equal sign (=); if there is only one keyword, the surrounding parentheses are optional.
An indirection operator and an expression atom evaluating to a list of one or more CLOSE arguments form a legal argument for a CLOSE.
When a CLOSE is issued, GT.M flushes all pending output to the device, and processes any deviceparameters. CLOSEing a device not currently OPEN has no effect.
If a partial record has been output, a WRITE ! is done to complete it. To suppress this action, set $X to zero before the CLOSE.
GT.M retains the characteristics of all device types, except a sequential file, for use in case of subsequent re-OPENs. If the device is a sequential file, characteristics controlled by deviceparameters are lost after the CLOSE.
If the device being CLOSEd is $IO, GT.M implicitly USEs $PRINCIPAL. GT.M ignores CLOSE $PRINCIPAL.
Example:
CLOSE SD:RENAME=SD_".SAV"
This closes the device and, if it is a disk file, renames it to have the type .SAV.
EXCEPTION=expr Applies to: All devices
Defines an error handler for an I/O device. The expression must contain a fragment of GT.M code (for example, GOTO ERRFILE) that GT.M XECUTEs when the driver for the device detects an error, or an entryref to which GT.M transfers control, as appropriate for the current gtm_ztrap_form.
The expression must contain a fragment of GT.M code (for example, GOTO ERRFILE) that GT.M XECUTEs when the driver for the device detects an error, or an entryref to which GT.M transfers control, as appropriate for the current gtm_ztrap_form.
For more information on error handling, refer to Chapter 13: “Error Processing”.
GROUP=expr Applies to: SD FIFO
Specifies access permission on a UNIX file for other users in the file owner's group. The expression is a character string evaluating to null or to any combination of the letters RWX, indicating respectively Read, Write, and eXecute access. When any one of these deviceparameters (OWNER, GROUP, WORLD) appear on a CLOSE of an existing file, any user category, that is not explicitly specified remains unchanged.
In order to modify file security, the user who issues the CLOSE must have ownership.
By default, CLOSE does not modify the permissions on an existing file.
OWNER=expr Applies to: SD FIFO
Specifies access permission on a UNIX file for the owner of the file. The expression is a character string evaluating to null or to any combination of the letters RWX, indicating respectively Read, Write, and eXecute access. When any one of these deviceparameters appear on a CLOSE of an existing file, any user category (GROUP, SYSTEM, WORLD), that is not explicitly specified remains unchanged.
In order to modify file security, the user who issues the CLOSE must have ownership.
By default, CLOSE does not modify the permissions on an existing file.
RENAME=expr Applies to: SD
Changes the file name to the name contained in the argument string. When the expression omits part of the pathname, GT.M constructs the full pathname by applying the defaults discussed in the section on device specifications.
If the process has sufficient access permissions, it may use RENAME to specify a different directory as well as file name. RENAME cannot move a file to a different filesystem.
SOCKET=expr Applies to: SOC
The socket specified in expr is closed. Specifying a socket that has not been previously OPENed generates an error. If no SOCKET deviceparameter is specified on a CLOSE for a socket device, the socket device and all sockets associated with it are closed.
SYSTEM=expr Applies to: SD FIFO
This deviceparameter is a synonym for OWNER that is maintained in UNIX for compatibility with VMS applications.
By default, CLOSE does not modify the permissions on an existing file.
UIC=exprgroup number Applies to: SD FIFO
Specifies the group that has access to the file. The format of the string is "g,i" where g is a decimal number representing the group portion of the UIC and i is a decimal number representing the individual portion.
Specifies the owner and affects access to the file. The expression evaluates to the numeric identifier of the new owner.
WORLD=expr Applies to: SD FIFO
Specifies access permissions for users not in the owner's group on a UNIX file. The expression is a character string evaluating to null or to any combination of the letters RWX, indicating respectively Read, Write, and eXecute access. When any one of these deviceparameters (OWNER, GROUP, WORLD) appears on a CLOSE of a new file, any user category that is not explicitly specified is given the default character string. When any one of these deviceparameters (OWNER, GROUP, WORLD) appears on a CLOSE of an existing file, any user category , that is not explicitly specified remains unchanged.
In order to modify file security, the user who issues the CLOSE must have ownership.
By default, CLOSE and CLOSE do not modify the permissions on an existing file. Unless otherwise specified, when CLOSE creates a new file, it establishes security using standard defaulting rules.
In order to modify file security, the user who issues the CLOSE must have ownership.