Ausam/doc/man/man1/em.1

Find at most related files.
including files from this version of Unix. 
.th EM I 10/1/79
.if t .ds q \(aa
.if n .ds q '
.sh NAME
em \*- text editor
.sh SYNOPSIS
.bd em
[
.bd \*-
[
.bd e
][
.bd l
][
.bd s
]
]
[ name ]
.sh DESCRIPTION
.it Em
is the Unix text editor and is also known as
.it e
and as
.it ed
\&.
When invoked as
.it em,
it prompts for commands with a `>'.
.s3
If a
.it name
argument is given,
.it em
simulates an
.it e
command (see below)\| on the named file; that is to say,
the file is read into
.it em's
buffer so that it can be edited.
The optional
.bd \*-
(by itself)
suppresses the printing
of character counts by
.it e,
.it r,
and
.it w
commands. The
.bd \*-e
flag puts
.it em
in `elfic' mode,
which forbids
.it e
and
.it w
commands, forbids
.it f
followed by a file name (unless no file name
was given when
.it em
was invoked),
forbids an
.it r
command not followed by a file name, and does an
automatic 
.it w
on quitting. The
.bd \*-l
flag executes an
.it l
instead of a
.it p
when a line number or a newline is given without a command.
The
.bd \*-s
flag suppresses the verbose error messages, in favour
of `?' and `??'.
.s3
.it Em
operates on a copy of any file it is editing; changes made
in the copy have no effect on the file until a \fIw\fR (write)\|
command is given.
The copy of the text being edited resides
in a temporary file called the 
.it buffer.
There is only one buffer.
.s3
Commands to
.it em
have a simple and regular structure: from zero to three
.it addresses
followed by a single or double character
.it command,
possibly
followed by parameters to the command.
These addresses specify one or more lines in the buffer.
Every command which requires addresses has default addresses,
so that the addresses can often be omitted.
.s3
In general, only one command may appear on a line.
Certain commands allow the input of text.
This text is placed in the appropriate place in the buffer.
While
.it em
is accepting text, it is said
to be in
\fIinput mode.\fR
In this mode, no commands are recognized;
all input is merely collected.
Input mode is left by typing a period `\fB.\fR' alone at the
beginning of a line.
.s3
.it Em
supports a limited form of
.it "regular expression"
notation.
A regular expression specifies
a set of strings of characters.
A member of this set of strings is said to be
.it matched
by the regular expression.
The regular expressions allowed by
.it em
are constructed as follows:
.s3
.lp +3 3
1.	An ordinary character (not one of those discussed below)\|
is a regular expression and matches that character.
In particular, all letters and numbers belong to this
class.
.s3
.lp +3 3
2.	A circumflex `^' at the beginning of a regular expression
matches the empty string at the beginning of a line.
.s3
.lp +3 3
3.	A currency symbol `$' at the end of a regular expression
matches the null character at the end of a line.
.s3
.lp +3 3
4.	A period `\fB.\fR' matches any character except a
new-line character (which is not matched by any character).
.s3
.lp +3 3
5.	A string of characters enclosed in square brackets
`[ ]' matches any character in the string but no others.
If, however, the first character of the string is a circumflex
`^' the regular expression matches any character except new-line
and the characters in the string.
Sequences or ranges of characters are specified with the `-'
character;  e.g.
.sp
.nf
.ti 10
[ams-vx-z] is equivalent to [amstuvxyz]
.fi
.sp
The `-' and `]' can be escaped with a `\\'.
.s3
.lp +3 3
6.	A regular expression followed by an asterisk `*'
matches any number of adjacent occurrences (including zero)\|
of the regular expression it follows.
This applies only to regular expressions mentioned above, i.e.,
single characters or equivalent.
.s3
.lp +3 3
7.	An ampersand `&' matches the last regular expression
used (in a previous command).
.s3
.lp +3 3
8.	A percent `%' matches the last replacement string
used in the last `s' or `x' command.
.s3
.lp +3 3
9.	The concatenation of regular expressions is a regular
expression which matches the concatenation of the strings
matched by the components of the regular expression.
.s3
.lp +3 3
10.	A regular expression enclosed between
the sequences
`\\(' and `\\)'is identical to the
unadorned expression; the construction has side effects discussed
under the
.it s
command.
.s3
.lp +3 3
11.	The null regular expression standing alone
is equivalent to the last regular expression encountered.
.s3
.i0
Regular expressions are used in addresses to specify
lines and in two commands
(see
.it s
and
.it x
below)\|
to specify a portion of a line which is to be replaced.
If it is desired to use one of
the regular expression metacharacters as an ordinary
character, that character may be preceded by `\\'.
This also applies to the character bounding the regular
expression (often `/')\| and to `\\' itself.
.s3
To understand addressing in
.it em
it is necessary to know that at any time there is a
\fIcurrent line.\fR
Generally speaking, the current line is
the last line affected by a command; however,
the exact effect on the current line
is discussed under the description of
the command.
Addresses are constructed as follows.
.s3
.lp +6 3
1.	The character `\fB.\fR' addresses the current line.
.s3
.lp +6 3
2.	The character `$' addresses the last line of the buffer.
.s3
.lp +6 3
3.	A decimal number
.it n
addresses the
\fIn\fR-th
line of the buffer.
.s3
.lp +6 3
4.	`\*q\fIx\fR' addresses the line marked with the
mark name character \fIx\fR,
which must be a lower-case letter.
Lines are marked with the
.it k
command described below.
.s3
.lp +6 3
5.	A regular expression enclosed in slashes `/' addresses
the first line found by searching toward the end of the
buffer and stopping at the first line containing a
string matching the regular expression.
If necessary the search wraps around to the beginning of the
buffer.
.s3
.lp +6 3
6.	A regular expression enclosed in queries `?' addresses
the first line found by searching toward the beginning of
the buffer and stopping at the first line containing
a string matching the regular expression.
If necessary
the search wraps around to the end of the buffer.
.s3
.lp +6 3
7.	An address followed by a plus sign `+'
or a minus sign `\*-' followed by a decimal number
specifies that address plus
or minus the indicated number of lines.
The plus sign may be omitted.
.s3
.lp +6 3
8.	If an address begins with `+' or `\-'
the addition or subtraction is taken with respect to the current line;
e.g. `\-5' is understood to mean `\fB.\fR\-5'.
.s3
.lp +6 3
9.	If an address ends with `+' or `\-',
then 1 is added or subtracted.
As a consequence of this rule and rule 8,
the address `\-' refers to the line before the current line.
Moreover,
trailing
`+' and `\-' characters
have cumulative effect, so `\-\-' refers to the current
line less 2.
.s3
.lp +6 3
10.	To maintain compatibility with earlier versions of the editor,
the character `^' in addresses is entirely
equivalent to `\-'.
.s3
.i0
Commands may require zero, one, or two addresses.
Commands which require no addresses regard the presence
of an address as an error.
Commands which accept one or two addresses
assume default addresses when insufficient are given.
.s3
Addresses are separated from each other typically by a comma
`\fB,\fR'.
They may also be separated by a semicolon
`\fB;\fR'.
In this case the current line `\fB.\fR' is set to
the previous address before the next address is interpreted.
This feature can be used to determine the starting
line for forward and backward searches (`/', `?')\|.
Where the address is omitted before (or after) the comma,
the default address is `1' (or `$'), respectively.
Thus, for example, `\fB,\fR' followed by a command is
equivalent to `1\fB,\fR$' followed by that command.
The second address of any two-address sequence
must correspond to a line following the line corresponding
to the first address.
.s3
In the following list of
.it em
commands, the default addresses
are shown in parentheses.
The parentheses are not part of
the address, but are used to show that the given addresses are
the default.
All commands may be in upper or lower case.
.s3
As mentioned, it is generally illegal for more than one
command to appear on a line.
However, any command may be suffixed by `p'
or by `l', in which case
the current line is either
printed or listed respectively
in the way discussed below.
.s3
.lp +5 5
( \fB. \fR)\| a
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.br
The append command reads the given text
and appends it after the addressed line.
`\fB.\fR' is left
on the last line input, if there
were any, otherwise at the addressed line.
Address `0' is legal for this command; text is placed
at the beginning of the buffer.
.s3
.lp +5 5
b
.lp +5 5
b+
.lp +5 5
b-
.br
The `break' command `b' (or `b+')
turns on automatic line breaks. During subsequent input to the `open'
command (see below), the first space after character position
60 of each line typed will be replaced by a `newline'.
Automatic line breaks are inserted only during input with one of
the variants of the `o' command.
They may be suppressed by the command `b-'.
If the current saved filename ends in `.n' or `.r',
then `b' is automatically invoked.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| c
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.br
The change
command deletes the addressed lines, then accepts input
text which replaces these lines.
`\fB.\fR' is left at the last line input; if there were none,
it is left at the first line not deleted.
.s3
.lp +5 5
cd pathname
.br
The change-directory command changes the current working
directory. The pathname may not contain the `%' or `@'
short cut of the shell.
On exit the current directory will be the
one before
.it em
was invoked.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| d
.br
The delete command deletes the addressed lines from the buffer.
The line originally after the last line deleted becomes the current line;
if the lines deleted were originally at the end,
the new last line becomes the current line.
.s3
.lp +5 5
e filename
.br
The edit
command causes the entire contents of the buffer to be deleted,
and then the named file to be read in.
`\fB.\fR' is set to the last line of the buffer.
The number of characters read is typed.
`filename' is remembered for possible use as a default file name
in a subsequent
.it r
or
.it w
command.
.s3
.lp +5 5
f filename
.br
The filename command prints the currently remembered file name.
If `filename' is given,
the currently remembered file name is changed to `filename'.
.s3
.lp +5 5
(1,$)\| g/regular expression/command list
.br
In the global
command, the first step is to mark every line which matches
the given regular expression.
Then for every such line, the
given command list is executed with `\fB.\fR' initially set to that line.
A single command or the first of multiple commands
appears on the same line with the global command.
All lines of a multi-line list except the last line must be ended with `\\'.
.it a,
.it i,
and
.it c
commands and associated input are permitted;
the `\fB.\fR' terminating input mode may be omitted if it would be on the
last line of the command list.
The (global)\| commands,
.it g,
and
.it v,
are not permitted in the command list.
.ne 6
.s3
.lp +5 5
h
.br
The help command displays a summary of the commands available in
.it em.
.s3
.lp +5 5
( \fB. \fR)\| i
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.br
This command inserts the given text before the addressed line.
`\fB.\fR' is left at the last line input; if there were none,
at the addressed line.
This command differs from the
.it a
command only in the placement of the
text.
.s3
.lp +5 5
( \fB. \fR, \fB.\fR+1 )\| j
.br
This command joins the addressed lines together.
The effect is as though the newlines
had been replaced with blanks.
.s3
.lp +5 5
( \fB. \fR, \fB.\fR+1 )\| jc
.br
This variant of the previous command joins the addressed lines together,
but also compresses the lines,
leaving only one blank at the join (throws
away any other blanks or tabs).
.s3
.lp +5 5
( \fB. \fR)\| k\fIx\fR
.br
The mark command marks the addressed line with
name
.it x,
which must be a lower-case letter.
The address form `\*q\fIx\fR' then addresses this line.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| l
.br
The list command
prints the addressed lines in an unambiguous way:
non-graphic characters are
printed in octal,
and long lines are folded.
An
.it l
command may follow any other on the same line.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| m\fIa\fR
.br
The move command repositions the addressed lines after the line
addressed by
.it a.
The last of the moved lines becomes the current line.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR) o
.lp +5 5
( \fB. \fR, \fB. \fR) o/regular expression/
.lp+5 5
( \fB. \fR, \fB. \fR) o+
.lp+5 5
( \fB. \fR, \fB. \fR) o-
.lp+5 5
( \fB. \fR, \fB. \fR) o\\
.br
The `open' command provides an additional level of editing
for interactive corrections during input of new lines of text
and for alterations to existing lines.
The first two forms of the `o' command operate on an existing
line. The line
is opened with the cursor positioned at the first occurence of the regular
expression if present,
otherwise at the start of the line.

The commands `o+', `o-' and `o\\' are equivalent to the `a', `i'
and `c' commands respectively, except in their use of the control
keys listed below, and in that they are not terminated by a line
containing a single `.', but by an ESCAPE or ctrl/d. `o;' is equivalent
to `o+'.
The erase and kill characters remain in effect during `o' editing.
In all variants of the `o' command it is possible to position
the cursor within the line, to delete characters, words or portions
of the line, 
and to insert new text at any point, using control keys
as follows:

.nf
.in +5
 
^a              re-display curent line to cursor
^b              move cursor back one word
ESCAPE or ^d    exit from `o' mode
^e              display all of current line
^f              delete forwards to end of current line
^p              skips to end of line
^q or ^c        display next character
^r              Release margin
^s              re-scan from start of current line
^t              backup one character
^w              display next word
^z              delete preceding word
RUBOUT          exit with current line unchanged
Other control characters (with a few exceptions) give
a summary of the control keys.
.in -5
.fi


Other characters (including RETURN) are inserted as typed.
When the automatic
line break facility is operative, a `bell' is transmitted to
the terminal before each newline is inserted. The newline may
be inhibited by the `^r' code.

.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| p
.br
The print command prints the addressed lines.
`\fB.\fR'
is left at the last line printed.
The
.it p
command may be placed on the same line after any command.
.s3
.lp +5 5
q
.br
The quit command causes
.it em
to exit.
No automatic write of a file is done, unless
.it em
was invoked with the
.bd \*-e
option.
.s3
.lp +5 5
($)\| r filename
.br
The read command
reads in the given file after the addressed line.
If no file name is given,
the remembered file name, if any, is used
(see
.it e
and
.it f
commands)\|.
The remembered file name is not changed unless
`filename' is the very first file name
mentioned.
Address `0' is legal for
.it r
and causes the
file to be read at the beginning of the buffer.
If the read is successful, the number of characters
read is typed.
`\fB.\fR' is left at the last line read in from the file.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\| s/regular expression/replacement/         or,
.lp +5 5
( \fB. \fR, \fB. \fR)\| s/regular expression/replacement/g        or,
.lp +5 5
( \fB. \fR, \fB. \fR)\| s/regular expression/replacement/n
.br
The substitute command searches each addressed
line for an occurrence of the specified regular expression.
On each line in which a match is found,
all matched strings are replaced by the replacement specified,
if the global replacement indicator `g' appears after the command.
If the global indicator does not appear, only the first occurrence
of the matched string is replaced.
It is an error for the substitution to fail on all addressed lines.
Any character other than space or new-line
may be used instead of `/' to delimit the regular expression
and the replacement.
`\fB.\fR' is left at the last line substituted.
.s2
An ampersand `&' appearing in the replacement
is replaced by the string matching the regular expression.
The special meaning of `&' in this context may be
suppressed by preceding it by `\\'.
A percent `%' appearing in a regular expression is replaced
by the  replacement string of the last `x'
or `s' command and can also be escaped
with `\\'.
As a more general feature,
the characters
`\\\fIn\fR',
where
.it n
is a digit,
are replaced by the text matched by the
\fIn\fR-th
regular subexpression
enclosed between `\\(' and `\\)'.
When
nested, parenthesized subexpressions
are present,
.it n
is determined by counting occurrences of `\\(' starting from the left.
.s2
If there is an `n' at the end of the command the number of replacements
made is printed.
The ending `gn' is also legal and has the obvious meaning.
Lines may be split by substituting newline characters into them.
The newline in the replacement string
must be escaped by preceding it by `\\'.
.s3
.lp +5 5
( \fB.\fR , \fB.\fR ) t \fIa\fR
.br
This command acts just like the
.it m
command, except that a copy of the addressed lines is placed
after address
.it a
(which may be 0).
`\fB.\fR' is left on the last line of the copy.
.s3
.lp +5 5
tin
.br
The time command causes an automatic `w' every n minutes.
If n is zero, the automatic `w' is stopped.
A bell character is sent to the terminal after each write.
This is useful in big editing sessions to avoid having to
periodically write the buffer.
.s3
.lp +5 5
(1,$)\| v/regular expression/command list
.br
This command is the same as the global command
except that the command list is executed
with `\fB.\fR' initially set to every line
.it except
those matching the regular expression.
.s3
.lp +5 5
(1,$)\| w filename
.br
The write command writes the addressed lines onto
the given file.
If the file does not exist,
it is created mode 600 (readable and writeable by owner)\|.
The remembered file name is
.it not
changed unless
`filename' is the very first file name mentioned.
If no file name is given,
the remembered file name, if any, is used
(see
.it e
and
.it f
commands)\|.
Two variations of `w' exist: `wa', which appends the addressed lines
to the given file, and `wx' which is equivalent to `w' but
makes the written file executable (mode 700).
`\fB.\fR' is unchanged.
If the command is successful, the number of characters written is
printed.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR) x/regular expression/replacement/
.br
The exchange command performs exactly the same functions
as an equivalent substitute command `s', except that it enables
the user to determine
interactively whether or not each replacement is to be
performed.
Each instance of the specified regular expression
is displayed, underscored with `^' characters.
The user must type `.' RETURN to perform the replacement or
just RETURN to omit it.

.s3
.lp +5 5
z
.br
This command lists (in the same format as the `l' command)
the current contents of the search buffer (as matched by
\&`&'), the replacement buffer (as matched by `%'),
and the UNIX command buffer (as matched by `!', see below).
.ne 5
.s3
.lp +5 5
( \fB. \fR) "n
.lp +5 5
( \fB. \fR) %n
.lp +5 5
( \fB. \fR) &n
.br
These commands allow the text being edited to be displayed
one page at a time - `"' displays one page of text below the
addressed line, `%' displays one page around the addressed line
(which is enclosed by a line of `-'s), and `&' displays one
page above the addressed line. `\fB.\fR' is left at the last
line printed, except for `%', where it is left at the addressed line.
The n, if present, specifies the page size (default 24 lines, minimum 4),
which becomes the default page size until reset by another size.
The lines may be listed instead, by appending `l' to the command.
.s3
.lp +5 5
($)\|=
.br
The line number of the addressed line is typed.
`\fB.\fR' is unchanged by this command.
.s3
.lp +5 5
!UNIX command
.br
The remainder of the line after the `!' is sent
to UNIX to be interpreted as a command.
.br
\&`!' anywhere in the UNIX command is replaced by the last
command executed in `!' mode (unless escaped by a `\\').
Thus `!more!junk' prepends `more' and appends `junk',
to the previous command; while `!!;!' does it again twice!
\&`%' anywhere in a `!' line is replaced by the currently selected
filename.
`\fB.\fR' is unchanged.
.s3
.lp +5 5
( \fB.\fR+1 )\| <newline>
.br
An address alone on a line causes the addressed line to be printed.
A blank line alone is equivalent to `.+1p' (or `.+1l' if
.bd \*-l
option is used); it is useful
for stepping through text.
.s3
.lp +5 5
>
.lp +5 5
<
.br
`>' turns prompting off; `<' turns it on again.
.s3
.i0
If an interrupt signal (ASCII DEL)\| is sent,
.it em
catches it and returns to its command level.
.s3
Some size limitations:
512 characters per line,
256 characters per global command list,
64 characters per file name,
and 256K characters in the temporary file.
The limit on the number of lines depends on the amount of core:
each line takes one word.
The temporary file is not exactly the same as the file being
edited;
if absolutely necessary, the original file may be recovered using
\&`edrecon'
(if available).
Also note that the temporary file is removed when you quit from
.it em
\&.
.sp
If the system is being shut down (gracefully),
.it em
is signalled causing it to write out its buffer into `saved.file',
and quit.
The user is informed with a terse message.
.sh FILES
/tmp/e#          temporary;
`#' is the process number (in octal).
.br
/usr/lib/emhelp  help messages
.sh DIAGNOSTICS
appropriate short phrases followed by `?'.
.ta 14 30
Some of the less esoteric error messages are these:
.nf
.sp
	Syntax	syntax (+ others)
	No match	match fail
	Open:	file non-existant
	Elfic	not allowed in elfic
	Address	illegal address(es)
	Reg name	invalid register name
	File		elfic - no file specified
	Interrupt	interrupted
	Line size	line too big
	Buffer empty	null file	
	Fork:	fork failed 
	Chdir:	chdir failed
	No `\\n' on last line - `\\n' added
	(n null(s) stripped from file)
.sp
.fi
The following errors are more serious and a guru should
be contacted if they occur:
.nf
.sp
	Create temp:	creat temp file failed
	Open temp:	open temp file failed
	Create:	creat fails
	Write:	write error
	Out of core	out of core
	Temp size	out of temp space
	Gtty:	gtty failed for std input
	Temp i/o:	i/o on temp file failed 
.fi
.ta 8 +8 +8 +8 +8 +8 +8 +8 +8
.sh "SEE ALSO"
.s3
grep(I), sed(I)
.br
Edit: A Tutorial