Accessing Files Programmer's Guide > Chapter 2 Creating A File

The FILE Command

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	E0300 Edition 6 ♥
	E0692 Edition 5

The FILE command is used to determine how a file will be accessed. You may use FILE to describe any of the characteristics available with HPFOPEN/FOPEN or BUILD, but you cannot actually create a file with the FILE command. While HPFOPEN/FOPEN and BUILD physically allocates space for a file and define its characteristics, the FILE command may only define how a file will be accessed at run time.

To be effective, a FILE command must be issued before your file is opened; it takes effect when the file is opened. A FILE command remains in effect until the job or session ends, until it is canceled with a RESET command, or until it is overridden by another command for the same file. Thus, if you enter a FILE command equating the formal designator DATAFL to the actual designator DISCFILE (indicating a disk file) and then run three programs that reference DATAFL, all three programs will access the file DISCFILE. If you wish to define other characteristics for the file, simply issue another FILE command; if you want to nullify the FILE command completely so that the formal designator has the characteristics originally specified by the program that is using it, issue a RESET command.

For example, suppose that you run two programs, both referencing a new temporary file named DFILE located on disk. Before you un the first program, you want to redefine the file so that it is output to the standard list device. To do this, you would issue a FILE command equating DFILE with the actual designator $STDLIST. In the second program, the file is again to be a temporary file on disk. You issue a RESET command so that the specifications supplied by the second program (rather than those in the FILE command) apply.


    JOB JNAME,UNAME.ANAME
   .
   .
   .
    FILE DFILE=$STDLIST
    RUN PROG1
   .
   .
   .
    RESET DFILE
    RUN PROG2
   .
   .
   .

A comparison of the parameters for FILE, FOPEN, and HPFOPEN is given in Table 2-3 "FILE, FOPEN, and HPFOPEN Parameters" For more information about using the FILE command, refer to the MPE/iX Commands Reference Manual.

Table 2-3 FILE, FOPEN, and HPFOPEN Parameters

CHARACTERISTIC	FILE PARAMETER	FOPEN PARAMETER	HPFOPEN PARAMETER
Formal file designator	`formal designator`	`formaldesignator`	`formaldesignator option (itemnum=2)`
Actual file designator	`filereference $NEWPASS $OLDPASS $NULL $STDIN $STDINX $STDLIST`	Default file designator `foption` (Bits 10:3)	`designator option (itemnum=5)`
Domain	`NEW OLD OLDTEMP`	Domain `foption` (Bits 14:2)	`domain option (itemnum=3)`
Logical record size	`recsize`	`recsize`	`record size option (itemnum=19)`
Block/buffer size	`blockfactor`	`blockfactor`	`block factor option (itemnum=40)`
Record format	`F V U`	Record format `foption` (Bits 8:2)	`record format option (itemnum=6)`
ASCII/Binary Code	`ASCII Binary`	ASCII/Binary `foption` (Bits 13:1)	`ASCII/Binary option (itemnum=53)`
Carriage-control characters supplied in FWRITE	`CCTL NOCCTL`	Carriage-control `foption` (Bits 7:1)	`carriage-control option (itemnum=7)`
Access mode	`IN OUT OUTKEEP APPEND INOUT UPDATE`	Access-type `aoption` (Bits 12:4)	`access type option (itemnum=11)`
Number of buffers	`numbuffers NOBUF`	`numbuffers` (Bits 11:5)	`numbuffers option (itemnum=44)`
Exclusive/Share access	`EXC SEMI SHR`	`EXCLUSIVE` access `aoption` (Bits 8:2)	`exclusive option (itemnum=13)`
Multi access	`MULTI NOMULTI GMULTI`	Multiaccess mode `aoption` (Bits 5:2)	`multiaccess option (itemnum=14)`
Multirecord	`MR NOMR`	Multirecord `aoption` (Bits 11:1)	`multirecord option (itemnum=15)`
File disposition	`DEL SAVE TEMP`	N/A	`final disposition option (itemnum=50)`
Device class name or logical device number	`device`	`device`	`device class option (itemnum=42) device name option (itemnum=20)`
Output priority	`outputpriority`	`numbuffers` (Bits 0:4)	`output priority option (itemnum=27)`
NOWAIT input/output	`NOWAIT WAIT`	`NOWAIT I/O aoption` (Bits 4:1)	`nowait I/O option (itemnum=16)`
Number of copies	`numcopies`	`numbuffers` (Bits 4:7)	`spooler copies option (itemnum=34)`
File code	`filecode`	`filecode`	`filecode option (itemnum=37)`
File capacity	`numrec`	`filesize`	`filesize option (itemnum=35)`
Total number of extents	`numextents`	`numextents`	`numextents option (itemnum=47)`
Extents initially allocated	`initalloc`	`initalloc`	`initial allocation option (itemnum=36)`
`FILE` command prohibition	N/A	Disallow `FILE` equation `foption` (Bits 5:1)	`disallow file equation option (itemnum=9)`
Dynamic file locking	`LOCK NOLOCK`	`Dynamic locking aoption` (Bits 10:1)	`disallow file equation dynamic locking option (itemnum=12)`
Forms-alignment message	`FORMS`	`formmsg`	`spooled message option (itemnum=28)`
User labels for disk file	N/A	`userlabels`	`user labels option (itemnum=33)`
File labels for magnetic tape files	`LABEL NOLABEL`	Labeled tape `foption` (Bit 6:1)	`labeled tape label option (itemnum=8)`
File type	`STD CIR MSG RIO`	file type `foption` (Bits 2:3)	`file type option (itemnum=10)`
Mapped access method	N/A	N/A	`short mapped option (itemnum=18) long mapped option (itemnum=21) large mapped option (itmenum=87)`
Restrict file access according to execution level	N/A	N/A	`privileged access option (itemnum=29) file privilege option (itemnum=38)`
Determine optimum pre-fetch algorithm	N/A	N/A	`will access option (itemnum=39)`
Fast file open	N/A	N/A	`UFID option (itemnum=43)`
Fill character for record padding	N/A	N/A	`fill character option (itemnum=45)`
Formal file designator Pascal/iX string type	N/A	N/A	`Pascal/iX string option (itemnum=51)`
File equation string for file open	N/A	N/A	`file equation string option (itemnum=52)`
KSAM key file record	N/A	KSAM param	`KSAM parm option (itemnum=54)`
User object class number	N/A	N/A	`object class option (itemnum=56)`

The BUILD Command

Summary of Overrides

The FILE Command

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