TOPS-20 Commands Reference Manual

PERUSE

Allows you to read a file using read-only editor commands.

Format

@PERUSE (FILE) /switch(es) filespec

where:

/switch(es)

are keywords that apply to the EDIT editor. For descriptions of these switches, see the /CREATE or EDIT commands.

filespec

is the name of the file you want to read.

Default

the last file specification and associated switches you gave in a CREATE, EDIT, or PERUSE command during the current terminal session

Characteristics

The PERUSE command runs the EDIT system program in read-only mode. (However, see Special Cases - Using an Editor Other than EDIT, below.) PERUSE is actually the same as the EDIT /READONLY command. In EDIT /READONLY mode you can use only EDIT program switches and commands that do not modify the file.

Hints

Avoid Accidental File Modification

Use PERUSE when it is important to avoid the risk of accidentally modifying a file.

PERUSE Line in SWITCH.INI

Add a line to your SWITCH.INI file for use with the PERUSE command. (See Example 3.)

Special Cases

Using an Editor Other than EDIT

The CREATE, EDIT and PERUSE commands in this manual assume that these commands call on the program EDIT. If your job uses another editing program, for example, EDT, the switches and examples shown here will not be applicable.

The Editor used by the CREATE, EDIT and PERUSE commands is specified by the logical name EDITOR:. You can find out the name of this program by giving the command, INFORMATION LOGICAL-NAMES EDITOR:. The job-wide definition (if any) will be given first, followed by the system-wide definition; the job-wide definition prevails if both exist. If the definition of EDITOR: is SYS:EDIT.EXE, the CREATE, EDIT and PERUSE commands will function as described in this manual. Otherwise, you must consult the appropriate manual (for example, the EDT-20 Reference Manual) for information.

Restrictions

Listing Available EDIT Read-Only Switches and Commands

Many of the EDIT switches and commands that are displayed in response to a ? modify the file and do not function with PERUSE. If you give a file-modifying switch, the switch is ignored but no error message is displayed. If you give a file-modifying EDIT command, you receive the message %ILLEGAL COMMAND.

For further information on these switches and commands see the EDIT Reference Manual.

Effect on Memory

The PERUSE command clears any unkept forks from memory, then loads your edit program.

Related Commands

CREATE	for creating new files
DIRECTORY-class commands	for getting lists of existing files
EDIT	for modifying files
TYPE	for printing files on your terminal

Examples

PERUSE a file

@PERUSE FILEX.FOR
Read: FILEX.FOR.1
*P
00100  !THIS IS FILEX.FOR

PERUSE a file, ten lines at a time, and begin at line 100.

@PERUSE /PLINES:10 FIND.BAS
Read: FIND.BAS
*P 100
00100   !       ADD ROUTINE
00200   FOR X = 0 TO 400
00300   IF X$(X) = "XXX" THEN GOTO 2050
00400   NEXT X
00500   PRINT STRING$(10,10);"FILE FULL"\SLEEP 4\GOTO 199
00600   PRINT E$ \LINPUT"ENTER THE NAME ";M$
00700   IF M$ <> "" THEN LET X$(X) = M$ ELSE GOTO 199
00800   PRINT E$ \LINPUT"ENTER THE NUMBER ";O$
00900   IF O$ <> "" THEN LET Y$(X) = O$ ELSE GOTO 199
01000   PRINT E$\INPUT"MORE NAMES TO ENTER ";D$
*E

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