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ECCE
the
Edinburgh Compatible Context Editor
ECCE is a program for creating, updating, and extending text
files. The design of ECCE is based on ideas developed by Alan
Freeman, Chris Whitfield, and Hamish Dewar. Numerous people within
both the department of Computer Science and the Edinburgh Regional
Computer Centre have contributed (to) implementations of ECCE.
L. D. Smith. 18/05/78
Contents
Section 1
Introduction. 1-1
1. The source file. 1-1
2. Commands. 1-1
3. Position within a file - the file pointer. 1-2
4. A simple subset of commands. 1-3
5. An example of the use of ECCE. 1-5
6. Text location and manipulation commands. 1-6
7. A further example of the use of ECCE. 1-8
8. Command failure. 1-9
9. Character manipulation commands. 1-10
10. Breaking and joining lines. 1-10
11. Monitoring commands. 1-11
12. The repetition command. 1-11
13. Context specification - D, F, T and U revisited. 1-12
14. Programmed commands. 1-13
Standard extensions. 1-15
15. Macros. 1-15
16. Secondary input. 1-15
Section 2
Alphabetical command summary. 2-1
Special commands. 2-1
Programmed command qualifiers. 2-1
Simple commands. 2-2
Section 3
Invoking ECCE - system dependencies. 3-1
Interdata 3-1
PDP9 or PDP15 3-1
EMAS 3-2
ICL2980 3-2
DEC system-10 3-3
PDP11, DEIMOS 3-5
PDP11, DOS 3-5
Other systems 3-6
Introduction
ECCE - the Edinburgh Compatible Context Editor - is a program for
creating, updating, and extending text files. Any line-structured
file can be manipulated by ECCE (but there could be problems if too
many of the characters in the file are non-printing!). Examples of
line-structured files include IMP and FORTRAN source files, and the
source text for documents such as this.
ECCE is implemented on most of the computers in both the Computer
Science Department and the Regional Computing Centre, and also on the
Science Research Council's DEC system-10.
1. The source file
Conceptually all editing operations are performed on a file.
Actually a source file is edited to an output file, leaving the
source unchanged, although often (or indeed usually) the output file
will have the same name as the source file and will overwrite or
replace the source file when ECCE terminates successfully. This, of
course, has the same apparent effect as directly editing the source
file.
2. Commands
After invoking ECCE, commands are issued from a console, one to a
line or many to a line, and in either upper or lower case. Spaces
have no significance, except within text strings, and command lines
are terminated either by a newline character or by a semi-colon (;).
After reading the command line the editor checks it for syntactic
correctness and then executes the individual commands in left to
right order. A syntax error in a command line (such as an unmatched
string delimiter) causes the whole command line to be ignored and an
error report to be produced (see paragraph 8. Command failure).
To terminate the editing session and close all input and output
files the command %C is issued (%C must be the only command in the
command line).
3. Position within a file - the file pointer
Editing commands (except the 'special' commands such as %C)
operate on the source text at the current position in the text. In
order to define the current position the editor maintains a pointer
henceforth called the file pointer. Conceptually this is always
between two characters of the source text, or immediately before the
first character of the file, or immediately before the end of file
marker. When printing out a line at the console the editor
identifies the file pointer by typing an up-arrow or caret character
in the appropriate position unless this is at the beginning of a line
(precisely which character is used to represent the file pointer
depends on the physical characteristics of the console).
For example
THIS IS AN UP-AR^ROW OR CARET CHARACTER.
BUT HERE THE FILE POINTER IS AT THE START OF THE LINE.
The end of file marker is identified at the console by the editor's
typing **END**.
For example
THIS IS THE LAST LINE OF MYFILE.
**END**
By default ECCE types out the current line after the execution of
each command line, unless two conditions are true. Firstly the line
must have been typed out in response to the immediately preceding
command line, and secondly the file pointer must not have been moved
(forwards or backwards) across a line boundary by the latest command
line.
4. A simple subset of commands
In this section a simple subset of ECCE's facilities will be
described. This is sufficient to perform most editing operations.
More sophisticated commands, and programmed commands, will be
described later. The commands described allow the file pointer to be
moved forwards and backwards in the source text, a line of source
text to be killed (removed), a line of text to be inserted into the
file, occurrences of a specified text string to be found, lines of
text to be printed, and the editing session closed.
All these commands (except %C) can be followed by a positive
integer, zero (0), or *, to specify how many times the command is to
be repeated. Zero and * denote indefinite repetition. That is,
until the command fails or a large, implementation dependent, number
of repetitions have been performed. Typically this large number is
set at 5000.
%C Close the editing session. The input and output files are
closed and control returned to the invoking system. %C must
be the only command in the command line.
M Move the file pointer to (just before) the start of the
next line. This fails if the file pointer is already at
the end of file marker (that is, after the last line of the
file).
M- Move the file pointer back to (just before) the start of
the previous line. This fails if the file pointer is
already at, or in, the first line of the file. It may also
fail because of implementation restrictions on how far back
the file pointer may be moved (on systems with only
sequential files the limit is determined by the available
buffer space).
K Kill the current line of text. That is, remove all
characters in the current line (including the end of line
character). The file pointer is left at the beginning of
the next line (as for M). This command fails if the file
pointer is already at the end of the file.
G Get a line of text from the console and insert it between
the end of the previous line (if any) and the start of the
current line. The file pointer is left at the start of the
current line (that is immediately after the gotten text).
The user is prompted for input with a colon (:) and the
command will fail if the first character of the input line
begins with a colon, in which case the file pointer is not
moved. The rest of the line after the colon (if present)
is treated as a command line.
F/TEXT/ Find TEXT. Search the rest of the file, starting at the
file pointer, for the first occurrence of the string TEXT.
/ is a string delimiter. Any character having no other
significance to the editor can be used for example ' or "
or . or $ (or / itself). The file pointer is left
immediately before the first occurrence of TEXT if TEXT is
found. Otherwise the command fails and the file pointer is
left at the end of the file. If the command is repeated,
then the occurrence of TEXT just found is ignored in the
subsequent search for TEXT (see paragraph 6. Text location
and manipulation commands).
P Print the current line at the console. If the multiple
form of P is used, for example P6 or P*, then a move (M) is
performed after the first and subsequent P's (but not after
the final one). In this way a sequence of lines may
conveniently be printed at the console. The simple command
P can never fail and does not move the file pointer. The
multiple form of the Print command (for example P10) fails
only if an implicit attempt is made to move beyond the end
of file marker (for example, trying to print 10 lines when
there are only 8 lines before the end of file), and always
leaves the file pointer at the start of the last line
printed (or at the end of the file).
The P command identifies the file pointer by typing a
caret or up-arrow character in the appropriate position,
unless this is at the start of a line. The end of file
marker is identified as **END**. It should be noted that
the multiple form of P is not strictly repetition, for the
effect of P followed by P is to print the current line
twice, whereas the effect of P2 is to print the current
line and the next line, and move the file pointer to the
start of the next line. Generally this does not cause any
problems or confusion.
5. An example of the use of ECCE
In this section ECCE is used interactively to create and update a
file of text, which will contain part of a poem by Roger McGough
called "Discretion". The complete dialogue between ECCE and the user
is displayed. The user is prompted for command lines with a '>'
character and for input with a ':'. Starred lines are ECCE's normal
(default) monitoring output (see paragraph 11. Monitoring commands).
Note that '*' is not printed at the console, and that '>' and ':' are
not inserted into the source text. Explanatory comments occur in the
right hand half of the line starting with a '/' character.
System prompts and invocation of ECCE are, of course, system
dependent (see section 3: Invoking ECCE - system dependencies) and an
arbitrary example is given.
xE N/POEM /invoke the editor (system dependent)
Edit /to make a new file
>g0 /get some lines of input
:Discretion
:Discretion is the better part of Valerie
:(though all of her is nice)
:lips as warm as strawberries
:eyws as cold as ice
:the very best of everything
:only will suffice
:not for her potatoes
:and pudding made of rice
:
:Not for hwr potatoes
:and puddings made of rice
:she takes carbohydrates like God takes advice
:: /end the input for now
>m-9 /move back 9 lines
* eyws as cold as ice
>k g /kill it and get a replacement
:eyes as cold as ice
>f/pudd/ /missed the 's' off the end
* and ^pudding made of rice
>k /delete the line
* /current line after deletion
>g /get a replacement
:and puddings made of rice
>f/hwr/ /Welsh boyo?
* not for ^hwr potatoes
>k g /kill it, and replace it
:not for her potatoes
>m* /move to end of file
* **END**
>g0 /and continue the input ...
: ...
6. Text location and manipulation commands
It is apparent from the above example that the use of only the
very limited subset of commands introduced so far is clumsy, tedious,
and error prone. The commands described below can be used to move
the file pointer to immediately before or after a specified text
string, and to insert, substitute, or delete specified strings of
text, rather than whole lines.
In many of the commands introduced in this section a search for a
text string is implied. This search always begins at the character
immediately following the file pointer, and fails, with the exception
of Find, if an end of line is encountered before the text is found.
Find fails only at the end of the file. In subsequent searches for
the text string, by any text location command, the occurrence just
found is ignored. The commands Find, Uncover, and Verify are text
location commands. The Delete command breaks this rule and will
delete the occurrence just found, however, it is not a text location
command since the specified text is removed from the file.
In all the following examples the '/' character is used as a
string delimiter. Any character with no other significance to the
editor could be used, for example ' or " or $ or . or ? (or /
itself).
F/TEXT/ Find TEXT. Search the rest of the file, starting at the
file pointer, for the first occurrence of TEXT. The file
pointer is left immediately before the first occurrence of
TEXT, if it is found. Otherwise the command fails and the
file pointer is left at the end of the file. If the
previous command was a text location command (F, V, or U,
see below) then the occurrence of TEXT just located is
ignored when searching for TEXT. This applies particularly
to the case of F's being repeated (for example, F/TEXT/5
which finds the 5th occurrence of TEXT).
S/STR/ Substitute STR for TEXT. If the previous command was
F/TEXT/ or V/TEXT/ or U/TEXT/ (see below) then delete TEXT
and insert STR. The file pointer is left immediately to
the right of STR. The command fails if the previous
command was not an F, a V, or a U. Note that STR may be
the null string, so that F/ABCD/S// effectively deletes the
first occurrence of ABCD.
T/TEXT/ Traverse TEXT. Search the current line, starting at the
file pointer, for the first occurrence of TEXT and move the
file pointer to immediately after it. If TEXT is not found
on the current line the command fails. In this case the
file pointer is not moved. Traverse is rather like Find
except that the file pointer is left after the occurrence
of TEXT, but it is not a text location command (cannot use
circumstances, for example when adding an 's' (or any other
ending) to the end of a word.
D/TEXT/ Delete TEXT. Search the current line, starting at the file
pointer, for the first occurrence of TEXT, then delete it.
The command fails if TEXT is not found within the current
line after the file pointer. If the command succeeds then
the file pointer is moved to the position previously
occupied by TEXT, otherwise the file pointer is not moved.
I/TEXT/ Insert the specified TEXT immediately before the file
pointer. The file pointer is left immediately after the
inserted TEXT. Insert may fail in some implementations of
ECCE owing to restrictions on the line length and/or the
command line length. If Insert fails then the file pointer
is not moved.
U/TEXT/ Uncover TEXT. Search the current line, starting at the
file pointer, for the first occurrence of TEXT and remove
all characters between the file pointer and the start of
TEXT (TEXT itself is not removed). The file pointer is
left immediately to the left of TEXT. If TEXT is not found
on the current line then the command fails and the file
pointer is not moved. Otherwise TEXT may be replaced by
using the S/STR/ (Substitute) command.
V/TEXT/ Verify that TEXT occurrs immediately to the right of the
file pointer. Fail otherwise. If successful, S/STR/ can
be used to substitute STR for the TEXT just verified (see
above for S). This command is of use in programmed
commands (see paragraph 14. Programmed commands).
The following combinations of commands are often found to be
useful
F/TEXT1/ S/TEXT2/
D/TEXT1/ I/TEXT2/
T/word/ I/ending/
U/./ /delete rest of sentence
U/./S/,/ /delete rest of sentence
/and change full stop to comma
7. A further example of the use of ECCE
In the earlier example of the use of ECCE only a very basic subset
of commands was used. In this section the same example is reworked
to show how the text location and manipulation commands, just
introduced, can be used to make the necessary changes more easily.
The comment and monitoring conventions, and the command and input
prompts, are exactly the same as in the previous example.
xE N/POEM /invoke the editor (system dependent)
Edit /to make a new file
>g0 /get some lines of input
:Discretion
:Discretion is the better part of Valerie
:(though all of her is nice)
:lips as warm as strawberries
:eyws as cold as ice
:the very best of everything
:only will suffice
:not for her potatoes
:and pudding made of rice
:
:Not for hwr potatoes
:and puddings made of rice
:she takes carbohydrates like God takes advice
:a surfeit of ambition
:is her particylar vice
:Valerie fondles lovers
:like a mousetrap fonles mice
:: /end the input for now
>m-0 /move back to start
* Discretion
>f/eyws/ s/eyes/ /correct first mistake
* eye^s as cold as ice
>f/pudding/t/g/ /missed the 's' off the end
* and pudding^ made of rice
>i.s. /so put the 's' back in
>f/hwr/ d/w/ /remove the mistake
* not for h^r potatoes
>i/e/ /and correct it
>f/y/ /look for next blunder
* she takes carboh^ydrates like God takes advice
/not there yet!
>f/y/ /so repeat the command
* is her partic^ylar vice
>d/y/ i/u/ /fix the error
/N.B. D is not a text location command
/so 'y' just Found is deleted
>f/nle/ s/ndle/
* like a mousetrap fondle^s mice
>%c /end the edit
x /next command prompt from system
/ (system dependent)
8. Command failure
A command can fail in two ways. Firstly it may be
syntactically incorrect, in which case the command line is ignored
and an error report produced, and secondly it may fail in
execution, in which case a failure report is produced, the current
line (at time of failure) is printed, and the rest of the command
line is ignored.
In general the failure of a simple command leaves the file
pointer unmoved, however, if the failing command is part of a
command line or repeated command then the file pointer is left
positioned by the last successful command.
Syntax errors include commands that are not recognised,
mismatched string delimiters, mismatched parentheses (see
paragraph 14. Programmed commands), command line size exceeded,
and so forth.
For example
>w
W? /unknown command
>f/hello.
TEXT FOR F? /mismatched string delimiters
>mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
SIZE? /command too long
>g/abc/
G /? /wrong syntax entirely
but note
>w;m /W (rest of command line) is ignored
/but M (next command line) is executed
Examples of execution failure might be
**END** /at end of file
>m /can't, so it will fail
FAILURE: M
**END**
and
>m /move to next line
How now brown cow.
>s/horse/ m /meaningless!
FAILURE: S'HORSE'
How now brown cow.
/note, move not executed
or
>p /print current line
How now brown cow.
>t/now/2 /note that 'now' occurs only once
FAILURE: T'now'
How now^ brown cow.
/2nd T/now/ not possible
or
>g3 /get 3 lines
:: /didn't mean it, so get out of G
FAILURE: G
... current line ...
/echo of current line on error
Note that indefinitely repeated commands such as g* produce no
failure reports, but that the failure condition is used to terminate
the repetition.
9. Character manipulation commands
Of the commands met so far M and M- move the file pointer past a
whole line and K deletes a whole line. The next four commands
operate at a finer level and move the file pointer past one
character, or delete one character, of the source text.
R Right shift the file pointer one character position. This
fails if the file pointer is already at the end of a line.
L Left shift the file pointer past one character position.
This fails if the file pointer is already at the beginning
of a line.
E Erase the character immediately to the right of the file
pointer. This fails if the file pointer is already at the
end of a line.
E- Erase the character immediately to the left of the file
pointer. This fails if the file pointer is already at the
beginning of a line.
10. Breaking and joining lines
The following commands are used to break a line into two parts,
and join two lines together.
B Break the current line into two parts at the file pointer.
That is, insert a newline character immediately to the left
of the file pointer, so that the second part becomes the
new current line. B never fails. Breaking a line at its
beginning (that is, when the file pointer is at the start
of the line) has the effect of inserting an empty line
immediately before it (which may also be achieved by means
of G, then replying carriage return to the G command).
J Join the current line and the next line together by
removing the newline character at the end of the current
line. This command fails if the new line length would
exceed the maximum allowed by the implementation. If the
command succeeds then the file pointer is left at the join.
Otherwise the file pointer is not moved.
11. Monitoring commands
There are three 'special' commands that are used to change the
amount of 'echoing' that ECCE performs. These have no effect on the
source text. Special commands must appear as the only command in the
command line.
%M Monitor normally. This is the default when ECCE is first
invoked. The current line of the source text is typed at
the console after the execution of each command line unless
two conditions hold true. Firstly the current line has
just been typed out in response to the immediately
preceding command line, and secondly the current command
line did not cause the file pointer to be moved across a
line boundary at any stage in its execution. The current
line is not re-echoed if the last command in the latest
command line was a Print command.
%F Full monitoring is turned on. The current line is typed
out after the execution of each command line unless the
last command executed was a print (P) command. Thus the
result of all command lines is displayed at the console.
%Q Quiet mode. Turn off all monitoring. The current line is
typed out only if explicitly requested by means of the
print (P) command, or if the command line fails.
12. The repetition command
A command line consisting solely of a number or * causes the
previous command line to be executed the specified number of times.
For this purpose repetition commands do not count as command lines,
so that it is the most recent non-repetition-command command line
that is repeated. Zero (0) or * causes the previous command line to
be executed until failure. For example
>M /move to the next line
>3 /move 3 more times (if possible)
>2 /move twice more (not 6 times)
>m-2 /move back two lines
>4 /now back 8 more (not 4)
>0 /all the way to the start of the file
>P3 /print the first 3 lines of the file
The cat
sat on
the mat. Clever cat.
> /ready for next command
Note that this command sequence was executed in quiet mode (see
above: Monitoring commands) and that '>' is ECCE's command prompt.
Text in the right hand half of the line after (and including) '/' is
explicative and is not typed at the console.
13. Context specification - D, F, T, and U revisited
So far D, F, T, and U have been presented with their default
contexts only. That is one line, with the exception of F which
operates on the rest of the file (see paragraph 6.: Text location and
manipulation commands). In fact the number of lines to be searched
by these commands can be specified explicitly. For example
D50/DELETE/ /search 50 lines at most
F10/HELP/ /search 10 lines at most
T3/END/ /search 3 lines
U*/./ /search rest of file
The effect of specifying a context is best explained with reference
to a specific command, for example, D50/DOG/. This operates in the
following way
(1) D1/DOG/ /search current line for DOG
(2) If found then Delete DOG and
terminate the command successfully.
(3) Has the D command been executed 50 times?
(4) If so then command fails.
(5) Otherwise Move to next line and GO TO (1)
If this command succeeds the effect is to delete the first occurrence
of DOG within the next 50 lines (current line + next 49 lines). If
it fails the effect is M49 (Note, M49, not M50).
The other examples above have the following effects respectively.
Find the first occurrence of HELP within the next 10 lines (or M9 if
HELP doesn't occur within the next 10 lines), Traverse the first
occurrence of END within the next 3 lines (or M2 if END does not
occur within the next 3 lines), and more dangerously, Uncover all
text up to the next '.' (or Kill the rest of the file if '.' does not
occur before the end of the file).
Note that this final command U*/./ is very dangerous, as all lines
of text passed are Killed.
These commands may also be repeated, for example
F15/HELP/2
This command seeks the string HELP within the rest of the current
line and the next fourteen lines, then, if successful, ignores the
occurrence just found and seeks HELP again within the rest of the new
current line and the fourteen lines following it. The command will
fail if any repetition of F15/HELP/ fails, in which case the effect
is either M14, or M28. If the command succeeds the file pointer is
left immediately before the second occurrence of HELP.
14. Programmed commands
Already the reader will have noticed that several commands may be
put on one command line to create a command 'program'. Also command
lines may be repeated a specified number of times, or until failure.
This section describes how more general 'programs' can be written.
( ) Bracketing. A string of commands bracketed together is
treated as one command for purposes of failure and
repetition. For example
(M I/ /)0
inserts four blanks at the start of each line of the rest
of the file.
? Optional execution. Any command failure condition is
ignored, for example
D/PHONE/?
deletes the word PHONE from the current line if it occurs
on the current line. Otherwise it does nothing.
\ Inverted failure (success) condition. A command followed
by \ has its failure condition inverted, and succeeds if
and only if it fails! For example
(MV/%R/\)0
This programmed command moves the file pointer to the start
of the next line then repeats if V/%R/ fails. That is, the
move is repeated until a line beginning with %R is found,
or until the repetition limit is exceeded (or until end of
file is reached).
, (comma) Alternative command sequences. Sequences of commands
separated by commas form alternatives. If the first
alternative fails the next is tried, and so on. If an
alternative succeeds then the following alternatives are
ignored. This allows a generalised IF-THEN-ELSE construct
to be programmed. For example
D/CAT/,D/DOG/,M
This command either deletes CAT or DOG on the current line,
or moves the file pointer to the start of the next line
(try to Delete CAT. IF unsuccessful THEN try to Delete
DOG. IF still unsuccessful THEN try to Move to next
line.). Note too that command lines may be broken
immediately after a comma and thus span two or more
physical lines.
For example
>D/CAT/,
D/DOG/,M
Note that one must be very careful when using commands with
alternatives. For example
MD/CAT/,MD/DOG/
would not have anything like the effect of the previous
example. In this case if D/CAT/ fails we move to the next
line and try D/DOG/. If DOG and CAT occurred on
consecutive lines and the command were started on a line
containing CAT (next line contains DOG) then no occurrences
of CAT or DOG would be deleted.
By judicious use of ( ) , ? \ and repetition, quite complex
editing sequences can be programmed. The examples below are fairly
difficult and the reader is invited to unravel them before looking at
the answers.
(D/CAT/ I/CHAT/ L* , D/DOG/ I/CHIEN/ L* , M)*
((T/X'/((RV/'/\)4,(LV/'/S/'0/L,)4 E-2 I/16_/ D/'/))0M)0
The first 'program' is fairly straightforward and translates the
words CAT and DOG to their french equivalents (but note that
catalogue gets translated to chatalogue!). The second example
changes hexadecimal numbers in the format X'n', X'nn', X'nnn', and
X'nnnn' to 16_nnnn. That is it puts in the leading zeroes to pad the
field width to four. Note also the following useful commands
(RM)0 /find the next empty line
(R0(LD/ /)0M)0 /remove trailing spaces from all lines
((I/ /M)60B6)0 /right shift all lines by four spaces
/and separate pages with 6 empty lines
This final command is useful for paginating a file before printing it
on a line-printer, but note the assumption of 66 lines per page.
Standard extensions
There are two widely implemented standard extensions to ECCE,
macros and secondary input. The implementation details of secondary
input vary, and two variants will be described.
15. Macros
Three macro commands can be defined, namely X, Y, and Z. When
invoked, the effect of a macro is exactly as if the macro body had
been typed instead of the macro invocation. For example
>%X=(RM)0 /note %X=<macro-body>
/not X=<macro-body>
This defines X to be the next-empty-line command (see above). The
effect of X in a command line is then exactly the same as (RM)0. It
should be noted that it is the length of the macro body that counts
towards the total command line length. Both macro body length and
command line length are restricted, typically to 64 characters and 40
command units (each comma, bracket, \, number, and simple command
counts as one unit). These limits are, however, very implementation
dependent.
It should be noted that when a macro is invoked the macro body
exactly replaces the macro name. For example if X were to be defined
as MK then
X4
is exactly equivalent to
MK4
and not to
(MK)4
as might be imagined.
Note that a macro can be defined as several command lines separated
by semicolons. For example
%X=f1/TEXT1/;f1/TEXT2/
16. Secondary input
Secondary input is a feature that allows parts of a second input
text to be merged with the source text. The secondary input text is
completely unchanged by any editing operations that might be
performed upon it.
To enter secondary input mode the command %S is issued, and from
this point ECCE prompts for commands with '>>' rather than '>'. To
leave secondary input mode another %S command is issued and ECCE then
prompts for commands with '>' again. A %C command issued in
secondary input mode has the same effect as in primary input mode,
and ends the editing session in the same way. A %S command must be
the only command in the command line.
While in secondary input mode ECCE maintains a second file pointer
to the secondary input text, and any editing commands issued in
secondary input mode cause the second file pointer to be moved. The
main file pointer remains at the point it was at when the %S command
was issued. If secondary input is re-entered then the secondary file
pointer is where it was when secondary input mode was last left.
Initially the secondary file pointer is at the beginning of the
secondary input file.
Most systems implementing secondary input (but not PDP9/PDP15) do
so by means of two more commands, Note, and Abstract. These are
issued in secondary input mode. The effect of Note is to note the
current position of the (secondary) file pointer. This overrides any
previously issued Note commands. The secondary file pointer can then
be moved using (in principle) almost any of ECCE's commands. Some
implementations prohibit commands that would normally insert or
remove text (for example I, S, D, U, K, G) and only allow the file
pointer to be moved. In addition, the EMAS implementation prohibits
the use of character manipulation commands. The effect of an
Abstract command is then to transfer all text from just after the
last Noted position to just before the current (secondary) file
pointer into the output text in a position just before the (main)
file pointer. The Abstract command may be repeated with the obvious
effect. Note that when an Abstract command is issued, the secondary
file pointer must be after the last Noted position, otherwise it
fails.
On the PDP9/PDP15 systems secondary input is managed in a
different manner. The details of leaving and entering secondary
input mode are identical, but there are no Note or Abstract commands.
Instead, all text passed by the secondary file pointer will be
included in the output file, and text that is not to be included must
be Killed, Erased, Uncovered, or Deleted before the file pointer is
moved past it. Only text occurring before the secondary file pointer
is inserted into the output file. It is not possible to move the
secondary file pointer backwards.
Examples
>%s /enter secondary input mode
>>f/read tag/ /move to position
%ROUTINE ^READ TAG(%INTEGER NAME)
>>mm- /to get to start of line!
>>n /note the position
>>(v/%end/\m)0m /move past end of routine
>>a /abstract the routine
>>%s /and back to main source
> /usual command prompt
In the PDP9/PDP15 implementation this would be
>%s /enter secondary input mode
>>(f1/read tag/\k)0 /kill until read tag
%ROUTINE ^READ TAG(%INTEGER NAME)
>>(v/%end/\m)0 /move to end of routine
%END
>>m /past end of routine
>>%s /back to main source
> /main prompt
Alphabetical command summary
The following section is an alphabetical summary of ECCE commands
It is split into three sections, the special commands which begin
with a % character and must occur one to a command line, the
programmed command qualifiers, and the simple commands. The
paragraph references are to the earlier paragraphs of this document.
Commands peculiar to specific implementations of ECCE are described
in the next paragraph.
Special commands
%C Close the editing session (paragraphs 2,4).
%F Full monitoring (paragraph 11).
%M Monitor normally (default). (paragraph 11).
%Q Quiet mode. No monitoring (paragraph 11).
%S Secondary input mode (paragraph 16).
%X= Macro definition (paragraph 15).
%Y= Macro definition (paragraph 15).
%Z= Macro definition (paragraph 15).
Programmed command qualifiers
( ) Bracket a group of commands for purposes of repetition and
failure (paragraph 14).
? Optional execution of command (paragraph 14).
\ Invert the failure condition (succeed if and only if the
command fails) (paragraph 14).
, Alternative execution (IF-THEN-ELSE...) (paragraph 14).
Simple commands
A Abstract all text between the last Noted position and the
file pointer (paragraph 16).
B Break. Insert a newline at the current position (paragraph
10).
D/TEXT/ Delete the first occurrence of TEXT (paragraphs 6,13).
E Erase the next character (paragraph 9).
E- Erase the previous character (paragraph 9).
F/TEXT/ Find the first occurrence of TEXT (paragraphs 4,6,13).
G Get a line of input (paragraph 4).
I/TEXT/ Insert TEXT at the current position (paragraph 6).
J Join the current line to the next line (paragraph 10).
K Kill the current line (paragraph 4).
L Left shift the file pointer (paragraph 9).
M Move the file pointer to the next line (paragraph 4).
M- Move the file pointer to the previous line (paragraph 4).
N Note the current position (paragraph 16).
P Print the current line (paragraph 4).
R Right shift the file pointer (paragraph 9).
S/STR/ Substitute STR for the TEXT just Found, Uncovered, or
Verified (paragraph 6).
T/TEXT/ Traverse TEXT. Move the file pointer past the next
occurrence of TEXT (paragraphs 6,13).
U/TEXT/ Uncover TEXT. Remove all characters between the file
pointer and the next occurrence of TEXT (paragraphs 6,13).
V/TEXT/ Verify that TEXT occurs immediately to the right of the
file pointer (paragraph 6).
X Macro invocation (paragraph 15).
Y Macro invocation (paragraph 15).
Z Macro invocation (paragraph 15).
Invoking ECCE - system dependencies
Interdata
ECCE is invoked on the Computer Science Department's Interdata
systems by a command of the form
E source/output
Secondary input and macros are not available in this implementation.
If the source filename is omitted, or the null filename N specified,
then a new output file is created. If the output filename is the
same as the source filename, or it is omitted, then the output file
overwrites the source file when |Gthe edit is closed. If the output
filename is the null filename N then all output is thrown away (this
is a convenient way to examine a file with no danger of altering it).
For example
E FRED/NEWFRED /FRED is unchanged
E MYPROG /MYPROG updated at end of edit
E /NEWPROG /create a new file NEWPROG
E LIST/N /examine LIST
PDP9 or PDP15
ECCE is invoked on the Computer Science Department's PDP9/15
systems by a command of the form
E source,secondary-input/output
Secondary-input may be omitted if not required. If the source
filename is omitted, or the null filename N specified, then a new
output file is created. If the output filename is the same as the
source filename, or it is omitted, then the output file overwrites
the source file when the edit is closed. If the output filename is
the null filename N then all output is thrown away (this is a
convenient way to examine a file with no danger of altering it).
For example
E MYPROG/NEWPROG /MYPROG unchanged
E PROGRAM /PROGRAM updated at end of edit
E PROG1,PROG2/DT3 MERGED /merge parts of PROG2 with PROG1
E /DT5 NEW FILE /create NEW FILE on DT5
E DT2 LIST/N /examine LIST on DT2
EMAS
Before using ECCE on EMAS it is neccessary to append CSDEPT.EDLIB.
It is then invoked by a command of the form
E(source,secondary-input/output)
If the source filename is omitted, or the null filename .NULL
specified, then a new output file is created. If the output filename
is the same as the source filename, or it is omitted, then the output
file overwrites the source file when the edit is closed. If the
output filename is the null filename .NULL then all output is thrown
away (this is a convenient way to examine a file with no danger of
altering it). For example
E(.NULL/NEWFILE) /create NEWFILE
E(FRED/FRED2) /FRED unchanged
E(FRED) /FRED updated at end of edit
E(PROG1,PROG2/MERGED) /merge parts of PROG2 with PROG1
E(LOOK/.NULL) /examine LOOK
ICL 2980
ECCE is invoked on the ICL 2980 by calling the macro ECCE with
parameters INPUT=, OUTPUT=, SECIN=, CONTROL=, LISTING=, and
RESPONSE=. These specify the input, output, secondary input,
control, and listing streams. SECIN may be omitted if not required,
and OUTPUT defaults to the next generation of the input file
(generation -3 is deleted to prevent the accumulation of old
versions). CONTROL defaults to the job-stream if not specified and
contains the commands to control ECCE. LISTING is the name of a file
to receive messages and error reports from ECCE. By default a
workfile is used which is automatically listed. RESPONSE specifies
the name of an integer SCL variable which will receive the result
code at the end of the edit. The default is RESULT. The result code
takes one of two possible values, namely 0 if there are no errors,
and 1 if the edit is abandoned because of an edit command failure.
Users wishing to use ECCE on the ICL 2980 should consult the ERCC
program advisory service for more detailed information.
Commands peculiar to the ICL 2980 implementation of ECCE
M# Move to absolute line number 'n'. This command fails if
there is no line 'n'.
K#n Kill all lines from the current line up to, but not
including, the line with absolute line number 'n'. This
command fails if the file pointer is already past line 'n'
or if line 'n' cannot be found. In the latter case all
lines from the current position up to some line with line
number greater than 'n' are deleted.
O/TEXT/ Observe TEXT. Move the file pointer to the first
occurrence of TEXT, outputting all lines between the
current file pointer position and TEXT to the console.
This command fails if TEXT does not occur before the end of
the file.
%A Abandon the edit. The editing session is abandoned with
the input file unchanged. If a Rewind command has been
issued then the input file reverts to the state it was in
when last rewound.
%P Print line numbers. When a line is printed it is preceded
by its line number enclosed in parentheses. If the line
has been created (not from input file) the line number is
printed as four blanks. This is the default mode of
operation for ECCE on the 2980.
%N No line numbers to be printed.
%D Display last line output. Due to restrictions on memory
size only a portion of a file can be held in memory. As
the file pointer is advanced through the file earlier
portions of the file have to be output to backing store and
cannot be re-edited. The %D command notifies the user of
the last line output to indicate how much of the file is
available for re-editing.
%R Rewind. The remainder of the input is copied to the output
file and both are closed. The newly generated file then
becomes the input file with the file pointer at the start
of it. Absolute line numbers now refer to positions in
this new file.
%O=n 'n' is an unsigned integer. The absolute record numbers
are adjusted so that the current record has record number
'n'. The command is ignored if the current record does not
possess an absolute line number.
DEC system-10
ECCE is invoked on the Science Research Council's DEC system-10 by
a command of the form
ECCE output=source,secondary-input
Secondary-input may be omitted if not required, in which case a
second copy of the source is made available as secondary-input. This
facility effectively allows blocks of text to be moved around in a
file, by copying the text from the copy of the source to the new
position in the output, then deleting the same block from the old
position in the output. Note that in secondary input mode, only the
five commands M, M-, F, T, and P, and the secondary input mode
commands N and A, are valid.
If the source filename is omitted then a new output file is
created. If the source filename is the same as the output filename,
or it is omitted, then the output file overwrites the source file
when the edit is closed. If the output filename is omitted then all
output is thrown away (this is a convenient way to examine a file
with no danger of altering it).
For example
ECCE NEW.TXT= /create NEW.TXT
ECCE FRED.TXT=SAM.TXT /SAM.TXT unchanged
ECCE MERGED.TXT=OLD.TXT,NEW.TXT
/merge parts of NEW with OLD
ECCE PROG.TXT /PROG.TXT overwritten by new version
ECCE =LOOK.LST /examine LOOK.TXT
ECCE /use last used ECCE parameters
There are several features of ECCE that are peculiar to the DEC
system-10 implementation. These are described below.
Whenever a file being modified by the ECCE is closed then a backup
copy with extension .BAK is made.
The switches /F/L/M/N/P/Q/U and /E are allowed after a file
specification to set the special modes %F, %L, %M, ... (see below, or
command summary) and /E specifies that input and output files are to
be encrypted and decrypted using the standard DEC-10 encryption
routines. ECCE asks for a password (up to 30 characters) for each
file. A null password (carriage return) specifies that no encryption
is to be done on that file.
At the start of execution, ECCE looks for the file ECCE.CMD in the
user's own file area, and, if it is found, starts reading commands
from that file. Thus special commands, macros, or even whole editing
sessions, can be defined. When a command file has been found ECCE
types out the message "Reading from command file".
The execution of a command line can be interrupted from the
console by typing control-C twice followed by REENTER. This forces
an immediate failure condition for the command line. Thus an
inadvertent K* could be aborted (if noticed soon enough) after
killing only a few lines rather than the whole file. The file
pointer is left at the line in which it was when execution was
interrupted.
Further details of the use of ECCE on the DEC system-10 can be
obtained from the DEC-10 user support group.
Commands peculiar to the DEC system-10 implementation of ECCE
%A Abort. Close all files, but do not rename the originals,
leaving the altered file with the extension .TEM.
%G Go. Close all files and execute the last COMPIL class
command.
%T Top. Reset the file pointer to the top of the file and
save all the editing so far in a file with extension .TMP.
%W Write. Save all the editing so far in a file with
extension .TMP but do not move the file pointer.
%N Normal case mode. Characters in text strings or input
using the G command are taken in the case in which they are
given (default).
%L Lower case mode. All characters in text strings, or input
using the G command, are converted to lower case.
%U Upper case mode. All characters in text strings, or input
using the G command, are converted to upper case.
%P Print mode. All non-printing control characters in the
file being edited are typed at the console as an up-arrow
(or caret) character followed by the appropriate letter,
for example tab=^I, cr=^M, lf=^J. When in this mode the
file pointer is typed as an underscore character _.
PDP11, DEIMOS
ECCE is invoked under DEIMOS by a command of the form
E source/output
Secondary input and macros are not available in this implementation
of ECCE. If the source filename is omitted, or the null filename N
specified, then a new output file is created. If the output filename
is the same as the source filename, or it is omitted, then the output
file overwrites the source file when the edit is closed. If the
output filename is the null filename N then all output is thrown away
(this is a convenient way to examine a file with no danger of
altering it). For example
E FILE/NEWFILE /FILE is unchanged
E MYFILE /MYFILE updated at end of edit
E /NEWFILE /create a new file NEWFILE
E LIST/N /examine LIST
PDP11, DOS
ECCE is invoked under DOS by a command of the form
R ECCE
The program then prompts "*"; type the filenames in the form
output=source
If the source filename is omitted then a new output file is created.
If the source filename is the same as the output filename, or it is
omitted, then the output file overwrites the source file when the
edit is closed. If the output filename is omitted then all output is
thrown away (this is a convenient way to examine a file with no
danger of altering it).
For example
* NEW= /create file NEW
* NEW=OLD /edit from OLD to NEW
* FILE /FILE updated at end of edit
* =LIST /look at LIST
Other systems
Several implementations of ECCE have been written in IMP (for
example, EMAS, PDP9/15) and so ECCE is easily implementable on any
system which supports IMP.