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E X T E N D E D C O M M A N D L A N G U A G E
U S E R S M A N U A L
version 2.0
Kenneth E. Budnik
Nov 1, 1982
GenRad, Inc.
300 Baker Ave.
Concord, MA. 01742
Contents
page
CHAPTER 1 -- INTRODUCTION TO XCL
1.1 Introduction . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Documentation Conventions . . . . . . . . . . . . . 1-2
CHAPTER 2 -- USING XCL
2.1 Invoking XCL . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Exiting from XCL . . . . . . . . . . . . . . . . . . 2-1
2.3 Displaying HELP information . . . . . . . . . . . . 2-2
2.4 Entering Commands . . . . . . . . . . . . . . . . . 2-2
2.5 Repeating the latest command . . . . . . . . . . . 2-2
CHAPTER 3 -- XCL COMMAND EDITING
3.1 Moving the Cursor . . . . . . . . . . . . . . . . . 3-1
3.2 Inserting characters into a command . . . . . . . . 3-1
3.3 Deleting parts of a command . . . . . . . . . . . . 3-1
CHAPTER 4 -- XCL COMMAND QUEUE
4.1 XCL Command Queue . . . . . . . . . . . . . . . . . 4-1
4.2 Recalling previously typed commands . . . . . . . . 4-2
4.3 Deleting commands from the queue . . . . . . . . . . 4-2
4.4 Inserting commands into the queue . . . . . . . . . 4-2
4.5 Modifying commands in the queue . . . . . . . . . . 4-3
4.6 Displaying the command queue . . . . . . . . . . . . 4-3
CHAPTER 5 -- XCL EXTENDED COMMANDS
5.1 XCL Extended Commands . . . . . . . . . . . . . . . 5-1
5.2 Erasing Files . . . . . . . . . . . . . . . . . . . 5-1
5.3 Recovering Files . . . . . . . . . . . . . . . . . . 5-2
5.4 Suspending XCL Execution . . . . . . . . . . . . . . 5-2
5.5 Halting XCL Execution . . . . . . . . . . . . . . . 5-3
5.6 Logging off the system . . . . . . . . . . . . . . . 5-3
CHAPTER 6 -- XCL INITIALIZATION
6.1 XCL Initialization File . . . . . . . . . . . . . . 6-1
6.2 Redefining XCL Extended Commands . . . . . . . . . . 6-1
6.3 Changing the Command Queue Length . . . . . . . . . 6-2
APPENDICES
A. XCL Restrictions . . . . . . . . . . . . . . . . . . A-1
B. Summary of XCL Functions and Commands . . . . . . . B-1
C. XCL HELP Screen . . . . . . . . . . . . . . . . . . C-1
Chapter 1 -- Introduction to XCL
1.1 Introduction
XCL is an extended command language for use with the VMS
operating system. XCL provides an interface between the user and
DCL to allow the implementation of features which are not provided
by DCL. XCL was designed to achieve three main goals:
1) to provide editing capability for modifying command lines
before they are issued.
1) to store previously entered commands and allow them to be
edited and reissued.
2) to provide a number of extensions to DCL such as the
ability to recover erased files.
XCL provides complete editing capabilities to allow
modification of the displayed command line. The cursor can be
moved to any point in the command and text inserted or deleted.
Cursor movement and text deletion can be accomplished on a
character, word or line basis.
XCL maintains a queue of the last twelve commands issued. Any
of the commands in the queue can be recalled, edited (if desired),
and then reissued. Recalled commands can be reissued in sequence
to allow the repetition of a commmon sequence of commands.
XCL provides the ability to recover erased files. All files
erased using the XCL ERASE command are saved by XCL until the user
logs off the system -- any file which is erased can be recovered
with the RECOVER command.
Chapter 1 -- Introduction to XCL
1.2 Documentation Conventions
The following documentation conventions are used in this manual:
ctrl/x a control character typed by holding down the
"control" key while typing the "x" key.
<x> an ASCII control character ,e.g. <lf> = line feed.
<enter> the "enter" key on the auxiliary keypad
kp/x auxiliary keypad key "x"
^ up arrow key
v down arrow key
-> right arrow key
<- left arrow key
Chapter 2 -- Using XCL
2.1 Invoking XCL
To invoke XCL type the command XCL. XCL can be invoked
automatically whenever the user logs onto the system by inserting
the following command into the user's login command file:
$ IF F$MODE .EQS. "INTERACTIVE" THEN XCL
XCL uses a # (pound sign) as its prompt. XCL will accept any
DCL commands as well as the XCL extended commands.
2.2 Exiting From XCL
There are three methods of exiting XCL depending on whether
the user wishes to temporarily suspend XCL, permanently exit XCL
or log off the system.
To temporarily suspend execution of XCL use the command
"DCL". The DCL command will suspend XCL and return control to DCL
but all status information is retained so that XCL can be
restarted in exactly the same state as before suspension.
To permanently exit from XCL and return control to DCL type
the command "EXIT" in response to the XCL # prompt. If XCL has
been exited in this manner it can be restarted by typing the XCL
command, however, any files which were erased during the previous
session will no longer be recoverable. Note that EXIT must be
entered from the keyboard. An EXIT command encountered in a
command file will terminate execution of that file and return
control to XCL.
To log off the system use the command "LOGOUT". This command
will carry out the necessary cleanup operations before exiting XCL
and logging off the system.
See Chapter 5 for further descriptions of the DCL, EXIT and
LOGOUT commands.
XCL cannot be exited by typing "STOP". XCL checks for the
STOP command and ignores it. However, if a command file is
executed under XCL and a STOP command is encountered then the
command file and XCL will both be stopped and control will be
returned to DCL. When using XCL all command files should terminate
execution with an EXIT command to return control to XCL.
Ctrl/C and ctrl/Y are ignored by XCL. However, typing ctrl/C
or ctrl/Y during program execution or command execution will abort
execution of that program or command and return control to XCL.
Chapter 2 -- Using XCL
2.3 Displaying Help Information
XCL will display a help screen whenever the HELP key is
pressed. The HELP key is the GOLD (PF1) key on the auxiliary
keypad. The HELP screen displays the layout of the function keys
and lists the extended XCL commands. See Appendix C for a listing
of the HELP screen.
2.4 Entering Commands
Commands are entered into XCL just as they are entered into
DCL. In addition, XCL provides a number of editing extensions to
save typing time.
XCL places three restrictions on command format:
1) each command is limited to 77 characters maximum.
2) each command must be complete on a single line.
3) all mandatory parameters must be supplied with the
command.
XCL provides three separate command terminators -- the <cr>
key, the <lf> key and the <enter> key. All three will cause the
displayed command to be executed. They differ in whether or not
the displayed command is stored into the command queue and on how
the queue pointer is advanced after command execution. See
Chapter 4 on the Command Queue for further explanation.
2.5 Repeating the Latest Command
The latest command can be reissued by using the = function.
This function must be typed in response to the # prompt as the
only character on the line. XCL will redisplay the previous
command line in place of the = and immediately issue the command
to DCL. The function will be executed immediately and does not
need to be terminated.
Note that this function repeats the last command which was
issued to DCL, not the last command stored in the queue. This
function does not use or change the queue or queue pointer.
Chapter 3 -- XCL Command Editing
3.1 Moving the Cursor
XCL provides a number of cursor movement functions to allow
easy editing of the displayed command line. It is possible to
move forward and backward by one character, one word, or the
entire line by pressing a single key. For cursor movement a word
is defined as a string of alpha-numeric characters including the
asterisk. (Note that this definition differs from the delete word
function definition).
The XCL functions for cursor movement are:
kp/7 - move cursor to beginning of line
kp/8 or <bs> - move cursor back one word
kp/9 or <tab> - move cursor forward one word
kp/- - move cursor to end of line
<- - move cursor back one character
-> - move cursor forward one character
3.2 Inserting Characters into a Command
Any character typed on the keyboard which is not an XCL
function or a control key will be inserted into the command at the
current cursor position. Any characters in the command following
the cursor position will be moved one space to the right to make
room for the new character. When the displayed command reaches
the maximum length then characters will no longer be inserted into
the command line and the bell will be rung to indicate that the
buffer is filled.
3.3 Deleting Part of a Command
XCL provides functions to delete one character, one word or
the entire command. When deleting a character it is possible to
delete the current character (i.e. the character pointed to by the
cursor) or the previous character. The delete word function
defines a word as a single non-alphanumeric character or a
contiguous string of alpha-numeric characters (including
asterisks). (Note that this definition differs from the move word
function definition).
The XCL function keys for deletion are:
kp/PF2 - delete entire command
kp/PF3 - delete next word
kp/PF4 - delete current character
<del> - delete previous character
Chapter 4 -- XCL Command Queue
4.1 XCL Command Queue
XCL maintains a circular queue of the last twelve commands
typed. (The queue is actually thirteen entries long but one entry
contains a null command to indicate the end of the queue). Any
command(s) in the queue can be recalled, edited (if desired), and
reissued. The length of the command queue can be changed by the
user in the XCLINI.COM file (see Chapter 6).
XCL maintains a queue pointer which points to one entry in
the queue. If there is a command stored in that position in the
queue then XCL will display it as if it had been typed by the
user. Whenever the queue pointer is moved within the queue the
stored command (if any) is displayed.
XCL provides three command terminators -- the <cr> key, the
<lf> key and the <enter> key. All three will cause the displayed
command to be executed. They differ in whether or not the
displayed command is stored into the command queue and on how the
queue pointer is advanced after command execution.
1) The <cr> key advances the queue pointer to the end of the
queue, stores the displayed command at the end of the
queue, and then executes the displayed command.
2) The <lf> key advances the queue pointer to the end of the
queue and executes the displayed command without storing
it into the queue.
3) The <enter> key over-writes the previously stored command
with the displayed command, executes the new command and
then advances the queue pointer to the next command in the
queue. The command in this queue position (if any) will
then be displayed.
The terminators are generally used in the following manner.
Commands are normally terminated with the <cr>. This terminator
is used to issue (or reissue) commands which will be saved at the
end of the queue. The <lf> terminator is used to issue a command
when the user does not want to store the command in the queue.
The <enter> terminator is used to re-issue a sequence of commands
from the queue or to change a command stored within the queue.
When a recalled command is reissued with the <enter> key then
the next command in the queue is automatically displayed at the
next prompt. This allows a sequence of commands to be reissued
with minimal typing. For example, it would be common to repeat
the following sequence of commands:
EDT TEST.MAR
MACRO TEST
LINK TEST
RUN TEST
Chapter 4 -- XCL Command Queue
4.2 Recalling Previously Typed Commands
XCL provides functions to allow movement within the queue:
kp/4 - move to first command in queue
kp/5 or ^ - move to previous command
kp/6 or v - move to next command
kp/7 - move to end of queue
If the queue pointer is positioned to the first command in
the queue then the kp/5 or ^ keys have no effect. When the queue
pointer is at the end of the queue (i.e. positioned to the null
command) then the kp/6 or v keys have no effect and the # prompt
is displayed in preparation for entry of a new command.
Whenever the queue pointer is positioned to a command in the
queue the command is displayed as if it had been typed by the
user. The displayed command can be edited, if desired. Note that
the editing is performed on the displayed command line and not on
the copy of the command which is in the queue. The contents of
the queue are not changed unless the edited command is issued with
the <enter> key (or the "replace command" function is used). If
the command is issued with the <cr> key or <lf> key then the copy
of the command in the queue is not modified.
4.3 Deleting Commands from the Queue
The "delete command" function (kp/1 key) is used to delete
the current command from the command queue. All commands
following it in the queue are moved up one position.
4.4 Inserting Commands into the Queue
The "insert command" function (kp/2 key) is used to insert a
command after the current position in the command queue. Note
that the command is inserted into the queue but it is not
executed. To use this function move to the command which the new
command will follow in the queue, use the "delete line" function
to clear the displayed command, type the new command and then
insert it into the queue. The queue pointer is left pointing to
the newly inserted command. This allows a sequence of commands to
be inserted easily. If the command queue is full when the "insert
command" function is issued then the top command in the queue is
discarded. (Note that it is therefore impossible to insert a new
command at the top of a full queue).
Chapter 4 -- XCL Command Queue
4.5 Modifying Commands in the Queue
The "replace command" function (kp/3 key) is used to replace
or modify a command in the queue. To use this function move to
the command to be replaced or modified, edit it (or delete it and
type the new command) and then issue the "replace command"
function. The displayed command will replace the previous command
in the queue. Note that the command will not be executed.
4.6 Displaying the Command Queue
The contents of the command queue may be displayed by using
the "display command queue" function (kp/0 key). This function
displays all commands in the queue and also moves the queue
pointer to the end of the queue.
Chapter 5 -- XCL Extended Commands
5.1 XCL Extended Commands
XCL provides a number of extended commands. These commands
are designed to provide features which are not supported by DCL.
Normal DCL symbol substitution may not be used for an XCL
extended command keyword. However, symbol substitution may be
accomplished by typing a command of the form:
# symbol :== 'keyword'
where "symbol" is the symbol to be substituted and "keyword" is
the extended command keyword. Note that the apostrophes are
required around the extended command keyword. Symbol substitution
may also be done in the XCLINI.COM startup command file (see
Chapter 6).
5.2 Erasing Files
One of the most useful features of XCL is the ability to
recover an erased file. XCL maintains a copy of all erased files.
These copies are not deleted until the user EXITs XCL or logs off
the system so that it is possible to recover ERASED files during
the current session.
XCL provides the ERASE command to erase files. The format of the
ERASE command is:
ERAse filespec,...
The filespec is any legal VMS file specification and may
include wild carding. An explicit or wildcard version number is
required in the file specification. The ERASE command may be
abbreviated down to ERA.
XCL creates a sub-directory named [.0XCL0] in the user's
login directory to hold the copies of erased files. All files in
the [.0XCL0] directory are deleted whenever XCL is exited by a
ctrl/c or the LOGOUT command.
The ERASE command works by issuing a COPY command to copy the
specified file(s) to the [.0XCL0] directory followed by a DELETE
command to delete the file(s) from the indicated or default
directory.
Chapter 5 -- XCL Extended Commands
5.3 Recovering Files
XCL provides the RECOVER command for file recovery. The format of
the RECOVER command is:
RECover filename,...
The filename indicates a file name, file extension and an
optional version number. A full file specification may not be
used -- no directory may be specified. Files can only be
recovered to the current default directory. A file version number
is optional in the RECOVER command. If a version number is
specified then the indicated file is recovered. If no version
number is specified then the indicated file in [.0XCL0] with the
highest version number will be recovered. In either case, the
exact version number is maintained regardless of any similarly
named files in the default directory. The RECOVER command may be
abbreviated down to REC.
The RECOVER command works by issuing a COPY command to copy
the specified file(s) from the [.0XCL0] directory to the current
default directory. Note that RECOVER does not delete the file
from the [.0XCL0] directory.
5.4 Suspending XCL Execution
XCL can be suspended temporarily by issuing the command
"DCL". This command exits XCL without disturbing any status
information and without deleting the files in the [.0XCL0]
directory. When XCL is restarted the complete previous status is
restored and all previously erased files are still recoverable.
The DCL command should only be entered at the keyboard. If a
DCL command is encountered in a command file its effect is the
same as an EXIT command.
5.5 Halting XCL Execution
XCL can be halted by typing the command "EXIT". The EXIT
command may be abbreviated to EXI. This command must be entered
from the keyboard. An EXIT command encountered in a command file
will cause the command file to terminate and control will be
returned to XCL. The EXIT command will delete all files in the
[.0XCL0] directory. Therefore, if XCL is restarted after an EXIT
command any previously erased files will no longer be recoverable.
Symbol substitution may not be used for the EXIT command.
Chapter 5 -- XCL Extended Commands
5.6 Logging Off the System
XCL provides the LOGOUT command to log off the system. The
LOGOUT command may be abbreviated down to LO. The LOGOUT command
provides for the following clean-up operations:
1) all files in the [.0XCL0] directory are deleted.
2) if the command file LOGOUT.COM exists in the user's
login directory it is executed.
3) a DCL LOGOUT command is issued (if one was not executed
in LOGOUT.COM).
Chapter 6 -- XCL Initialization
6.1 XCL Initialization File -- XCLINI.COM
The user may specify a startup command file containing
commands to be executed whenever XCL is started. The use of this
file is optional and it needs to exist only if the user wishes to
change XCL defaults or to redefine the XCL extended commands. If
the startup command file is used, then it must be named XCLINI.COM
and must reside in the users login directory.
6.2 Redefining XCL Extended Commands
Normal DCL symbol substitution may not be used for an XCL
extended command keyword. However, symbol substitution may be
accomplished by typing a command of the form:
# symbol :== 'keyword'
where "symbol" is the symbol to be substituted for and "keyword"
is the extended command keyword. Note that the apostrophes are
required around the extended command keyword. This command may
also be entered into the XCLINI.COM command file in the user's
login directory.
An example of an XCLINI.COM file to allow substitution of DEL
for ERASE and BYE for LOGOUT is:
$ DEL :== 'ERASE'
$ BYE :== 'LOGOUT'
$ EXIT
6.3 Changing the Command Queue Length
The default command queue length is twelve commands. This
length may be changed in the XCLINI.COM file by a command of the
form:
$ XCL$QUELEN == n
where 'n' is the desired queue length. If a size less than 1 or
greater than 25 is specified then the default length of 12 will be
used. Note that if a queue length greater than 23 is specified
then the "display command queue" function is not able to display
the entire queue in a single screen -- the top commands scroll
off.
Appendix A -- XCL Restrictions
The following restrictions must be observed when using XCL.
1. The input line is restricted to a maximum of 77 characters and
the entire command must appear on a single line. If a command
longer than 77 characters is required then the command must
either be entered into a DCL command file or XCL must be
exited and the command issued directly from DCL.
2. XCL will not prompt for mandatory parameters on commands as
DCL does. Each XCL command must be complete with all required
parameters or DCL will issue the error message %DCL-W-INSFPRM,
insufficient parameters.
3. The DCL command ASSIGN/USER will not work properly when issued
from XCL. Either use the ASSIGN command or issue the
ASSIGN/USER command from within a DCL command file.
4. XCL sets the mode of the auxiliary keypad to application mode
(i.e. keypad keys will transmit escape sequences). Any
application which requires the keypad in numeric mode must
change the mode explicitly or else the application must be
called from a command file which first changes the keypad to
numeric mode.
5. If a command file is executed under XCL and a STOP command is
encountered then the command file and XCL will both be stopped
and control will be returned to DCL. When using XCL all
command files should terminate execution with an EXIT command
to return control to XCL.
6. Whenever XCL is exited by an EXIT command and later restarted
the previous command queue will be recovered. However, all
files in the [.0XCL0] directory will be deleted so that they
are no longer recoverable.
7. Always use the EXIT or LOGOUT command to permanently exit XCL.
If XCL is STOPed (from a command file) or exited by the DCL
command or if the user logs out using the DCL LOGOUT command
then the files in the [.0XCL0] directory are not deleted.
8. Normal symbol substitution may not be used for an XCL extended
command keyword. Symbol substitution must be accomplished by
a command of the form: #symbol:=='keyword' (note the
apostrophes around the keyword).
Appendix B -- Summary of XCL Functions and Commands
XCL Function Keys
-----------------
kp/7 - move cursor to beginning of line
kp/8 or <bs> - move cursor back one word
kp/9 or <tab> - move cursor forward one word
kp/- - move cursor to end of line
<- - move cursor back one character
-> - move cursor forward one character
kp/PF1 - display HELP screen
kp/PF2 - delete entire command line
kp/PF3 - delete next word in command line
kp/PF4 - delete current character in command line
<del> - delete previous character in command line
kp/0 - display entire command queue
kp/1 - delete command from queue
kp/2 - insert command into queue (without executing it)
kp/3 - replace command in queue (without executing it)
kp/4 - move to first command in command queue
kp/5 or ^ - move to previous command in command queue
kp/6 or v - move to next command in command queue
kp/7 - move to end of command queue
<cr> - move pointer to end of queue, store command
in queue, issue command
<lf> - move pointer to end of queue and issue
command without storing it
<enter> - issue command, store it in command queue,
advance pointer to next command in queue
= - repeat last command issued to DCL
(must be only character on line)
Appendix B -- Summary of XCL Functions and Commands
XCL Extended Commands
---------------------
ERAse - erase the indicated file(s)
RECover - recover the indicated file(s)
DCL - suspend XCL saving all status information
EXIt - halt XCL execution
LOgout - log off the system
Appendix C -- XCL HELP Screen
+-------+-------+-------+-------+ +-------+-------+-------+-------+
| prev | next | back | fwrd | | | del | del | del |
| cmnd | cmnd | one | one | | help | line | word | char |
| | | char | char | | | | | |
+-------+-------+-------+-------+ +-------+-------+-------+-------+
| | back | fwrd | |
c o n t r o l k e y s | BOL | one | one | EOL |
----------------------- | | word | word | |
<bs> - back one word +-------+-------+-------+-------+
<tab> - forward one word | begin | prev | next | end |
<lf> - execute cmnd, don't store | of | cmnd | cmnd | of |
= - reissue last command | queue | | | queue |
+-------+-------+-------+-------+
|delete |insert |replace| |
X C L c o m m a n d s | queue | queue | queue | |
----------------------- | entry | entry | entry | |
ERAse - erase file +-------+-------+-------+ ENTER |
RECover - recover file | display | | |
DCL - temporary return to DCL | command | . | |
EXIt - halt XCL | queue | | |
LOgout - log off the system +---------------+-------+-------+