PWB1/usr/man/man1/ed.1

.th ED I 5/31/77
.if t .ds q \(aa
.if n .ds q '
.sh NAME
ed \*- text editor
.sh SYNOPSIS
.bd ed
[
\fB\-\fP
] [
.bd +
] [ name ]
.lp
.i0
.sh DESCRIPTION
.it Ed
is the standard text editor.
.s3
If the
.it name
argument is given,
.it ed
simulates an
.it e
command (see below) on the named file; that is to say,
the file is read into
.it ed's
buffer so that it can be edited.
The optional
`\fI\(mi\fR'
suppresses the printing
of character counts by
.it e,
.it r,
and
.it w
(or
.it z
)
commands.
.s3
.it Ed
operates on a copy of the file it is editing; changes made
in the copy have no effect on the file until a \fIw\fR or \fIz\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.
.tr ~
.br
.s3
If changes have been made in the buffer since the last \fIw\fR or \fIz\fR command,
.it ed
warns the user if an attempt is made to destroy
.it ed's
buffer via the \fIq\fR or \fIe\fR commands.
.it Ed
prints `q?' or `e?', respectively,
and allows one to continue editing.
A second \fIq\fR or \fIe\fR command
at this point will take effect.
This warning feature may be inhibited by specifying the `+'
option (e.g., ed\ \ +\ \ file).
The `\(mi' option also inhibits this feature.
.s3
.tr ~~
.br
Commands to
.it ed
have a simple and regular structure: zero, one, or two
.it addresses
followed by a single character
.it command,
possibly
followed by parameters to that command.
These addresses specify one or more lines in the buffer.
Every command that 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 ed
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 Ed
supports a limited form of
.it "regular expression"
notation;
regular expressions are used in addresses to specify
lines and in some commands
(e.g., \fIs\fP\^)
to specify portions of a line that are to be replaced.
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 ed
are constructed as follows:
.s3
The following
.it "one-character regular expressions"
match a single character:
.s3
.lp +7 4
1.1	An ordinary character
(\c
.it not
one of those discussed in 1.2 below)
is a
one-character regular expression
that matches itself.
.s3
.lp +7 4
1.2	A backslash `\\' followed by any special character is a
one-character regular expression
that matches the special character itself.
The special characters are:
.s3
.lp +10 3
a.	`\fB.\fP',
`*',
`+',
`[',
and
`\\' (period, asterisk, plus sign, left square bracket, and backslash, respectively), which are always special,
except when they appear within square brackets `[\|]' (see 1.4 below).
.s3
.lp +10 3
b.	`^' (caret or circumflex), which is special at the beginning of an
.it "entire regular expression"
(see 3.1 and 3.2 below),
or when it immediately follows the left of a pair of square brackets `[\|]' (see 1.4 below).
.s3
.lp +10 3
c.	`$' (currency symbol), which special at the end of an
entire regular expression
(see 3.2 below).
.s3
.lp +10 3
d.	The character used to bound
(i.e., delimit) an entire regular expression, which is special for that regular expression (for example,
see how `/' is used in the \fIg\fP command, below.)
.s3
.lp +7 4
1.3	A period `\fB.\fP' is a
one-character regular expression
that matches any character except the new-line character.
.s3
.lp +7 4
1.4	A non-empty string of characters enclosed in square brackets `[\|]' is a
one-character regular expression
that matches
.it "any one"
character in that string.
If, however, the first character of the string is a circumflex
`^', the
one-character regular expression
matches any character
.it except
new-line and the remaining characters in the string.
The `^' has this special meaning
.it only
if it
occurs first in the string.
The minus `\*-' may be used to indicate a range of consecutive \s-2ASCII\s0 characters;
for example, [0\*-9] is equivalent to [0123456789].
The `\*-' loses this special meaning if it occurs first (after
an initial `^', if any)
or last in the string.
The `]'
does not terminate such a string when it occurs first (after an initial `^', if any),
in it, e.g., `[\|]a]' matches either a right square
bracket `]' or the letter `a'.
The five characters listed in 1.2.a above stand for themselves
within such a string of characters.
.s3
.i0
The following rules may be used to construct
.it "regular expressions"
from
.it "one-character regular expressions:"
.s3
.lp +7 4
2.1	A
one-character regular expression
is a
regular expression
that matches whatever the
one-character regular expression matches.
.s3
.lp +7 4
2.2	A
one-character regular expression
followed by an asterisk `*' is a
regular expression
that matches
.it zero
or more occurrences of the
one-character regular expression.
If there is any choice, this
regular expression
matches as many occurrences as possible.
.s3
.lp +7 4
2.3	A
one-character regular expression
followed by a plus `+' is a
regular expression
that matches
.it one
or more occurrences of the
one-character regular expression.
If there is any choice, this
regular expression
matches as many occurrences as possible.
.s3
.lp +7 4
2.4	A
one-character regular expression
followed by `\\{\|\fIm\fP\|\\}',
`\\{\|\fIm,\fP\|\\}',
or
`\\{\|\fIm,n\fP\|\\}' is a
regular expression
that matches a
.it range
of occurrences of the
one-character regular expression.
The values of
.it m
and
.it n
must be non-negative integers less than 256;
`\\{\|\fIm\fP\|\\}'
matches exactly
.it m
occurrences;
`\\{\|\fIm,\fP\|\\}'
matches at least
.it m
occurrences;
`\\{\|\fIm,n\fP\|\\}'
matches any number of occurrences between
.it m
and
.it n
inclusive.
Whenever a choice exists,
the
regular expression
matches as many occurrences as possible.
.s3
.lp +7 4
2.5	The concatenation of
regular expressions
is a
regular expression
that matches the concatenation of the strings matched by each component of the
regular
expression.
.s3
.lp +7 4
2.6	A
regular expression
enclosed between the character sequences
`\\(' and `\\)'
is a
regular expression
that matches whatever the unadorned
regular expression
matches;
this construction has side effects discussed under the
.it s
command, below.
.s3
.i0
Finally, an
.it "entire regular expression"
may be constrained to match only an initial segment or final segment
of a line (or both):
.s3
.lp +7 4
3.1	A circumflex `^' at the beginning of an
entire regular expression
constrains that regular expression to match an
.it initial
segment of a line.
.s3
.lp +7 4
3.2	A currency symbol `$'
at the end of an
entire regular expression
constrains that
regular expression
to match a
.it final
segment of a line.
The construction
.it "\%^entire regular expression$"
constrains the
entire regular expression
to match the entire line.
.s3
.i0
The null regular expression standing alone (e.g., `//')
is equivalent to the last regular expression encountered.
.i0
.s3
To understand addressing in
.it ed
it is necessary to know that at any time there is a
\fIcurrent line.\fR
Generally speaking, the current line is
the last line affected by a command;
the exact effect on the current line
is discussed under the description of
the command.
Addresses are constructed as follows:
.s3
.lp +6 3
1.	The character `\fB.\fR' addresses the current line.
.s3
.lp +6 3
2.	The character `$' 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 by slashes `/' addresses
the first line found by searching forward
from the line \fIfollowing\fR the current line
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
and continues through the current line, so that the entire
buffer is searched.
.s3
.lp +6 3
6.	A regular expression enclosed in queries `?' addresses
the first line found by searching backward
from the line \fIpreceding\fR the current line
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
and continues through the current line.
.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
(respectively 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, respectively.
As a consequence of this rule and of rule 8,
the address `\-' refers to the line preceding the current line.
Moreover,
trailing
`+' and `\-' characters
have a cumulative effect, so `\-\-' refers to the current
line less 2.
.s3
.lp +6 4
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 that require no addresses regard the presence
of an address as an error.
Commands that accept one or two addresses
assume default addresses when an insufficient number of addresses is given;
if more addresses are given than such a command requires,
the last one(s) are used.
.s3
Typically, addresses are separated from each other by a comma
`\fB,\fR'.
They may also be separated by a semicolon
`\fB;\fR'.
In the latter case, the current line `\fB.\fR' is set to
the first address before the second address is interpreted.
This feature can be used to determine the starting
line for forward and backward searches (see items 5. and 6. in the list above).
The second address of any two-address sequence
must correspond to a line that follows, in the buffer, the line corresponding to the first address.
.s3
In the following list of
.it ed
commands, the default addresses
are shown in parentheses.
The parentheses are \fInot\fR part of
the address, but are used to show that the given addresses are
the default.
.s3
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,
as discussed below under the
.it p
and
.it l
commands.
.s3
.if t .ne 7
.lp +5 5
( \fB. \fR)\|a
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.lp +5 5
	The \fIa\fR\^ppend command reads the given text
and appends it after the addressed line.
`\fB.\fR' is left
at the last inserted line; or, if there
were none, at the addressed line.
Address `0' is legal for this command: text is placed
at the beginning of the buffer.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\|c
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.lp +5 5
	The \fIc\fR\^hange
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
( \fB. \fR, \fB. \fR)\|d
.br
The \fId\fR\^elete command deletes the addressed lines from the buffer.
The line after the last line deleted becomes the current line;
if the lines deleted were originally at the end of the buffer,
the new last line becomes the current line.
.s3
.lp +5 5
e name
.br
The \fIe\fR\^dit
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.
If no file name is given, the remembered file name, if any, is used
(see the \fIf\fP command).
The number of characters read is typed;
\fIname\fP is remembered for possible use as a default file name
in subsequent
.it e
or
.it r
or
.it w
or
.it z
commands.
.s3
.lp +5 5
f name
.br
If \fIname\fP is given,
the \fIf\fR\|\|ilename command changes
the currently remembered file name to \fIname\fP\^;
otherwise, it prints the currently remembered file name.
.s3
.lp +5 5
(1,$)\|g/regular expression/command list
.br
In the \fIg\fR\^lobal
command, the first step is to mark every line that matches
the given \fIregular expression\fP.
Then, for every such line, the
given \fIcommand list\fR is executed with `\fB.\fR' initially set to that line.
A single command or the first of a list of commands
appears on the same line as the global command.
All lines of a multi-line list except the last line must be ended with a `\\';
.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 the
last line of the \fIcommand list\fP.
The (global) commands
(\c
.it "g, v, G,
and
.it V
)
are
.it not
permitted in the \fIcommand list\fP.
.s3
.lp +5 5
.br
( \fB. \fR)\|h
.br
The date as returned by
\fIdate\fP\^(I)
is appended after the addressed line.
.s3
.lp +5 5
( \fB. \fR)\|i
.lp +5 5
<text>
.lp +5 5
.li
\fB.\fR
.br
The \fIi\fR\^nsert command inserts the given text before the addressed line.
`\fB.\fR' is left at the last inserted line; or, if there were none,
at the addressed line.
This command differs from the
.it a
command only in the placement of the
input
text.
.s3
.lp +5 5
(\fB. \fR, \fB.\fR+1 )\|j
.br
The
\fIj\fR\^oin command joins contiguous lines by removing the appropriate new-line characters.
.s3
.lp +5 5
( \fB. \fR)\|k\fIx\fR
.br
The mar\fIk\fR 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
.if t .ne 6
.lp +5 5
( \fB. \fR, \fB. \fR)\|l
.br
The \fIl\fR\|ist command
prints the addressed lines in an unambiguous way:
a few non-printing characters (e.g.,
\fItab, backspace\fP\^)
are represented by (hopefully) mnemonic overstrikes, all other non-printing
characters are
printed in octal,
and long lines are folded.
An
.it l
command may also be appended to any other command.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\|m\fIa\fR
.br
The \fIm\fR\^ove command repositions the addressed line(s) after the line
addressed by
.it a.
Address `0' is legal for \fIa\fR and causes the addressed line(s) to be moved to
the beginning of the file;
it is an error if address
.it a
falls within the range of moved lines.
The last line so moved becomes the current line.
.s3
.lp +5 5
( \fB. \fR, \fB. \fR)\|p
.br
The \fIp\fR\^rint command prints the addressed lines;
`\fB.\fR'
is left at the last line printed.
The
.it p
command
may
be appended to any other command
(e.g., `\fIdp\fP'
deletes the current line and prints the
new current line).
.s3
.lp +5 5
q
.br
The \fIq\fR\^uit command causes
.it ed
to exit.
No automatic write
of a file is done.
.s3
.lp +5 5
($)\|r name
.br
The \fIr\fR\^ead 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
\fIname\fP is the very first file name
mentioned
since
.it ed
was invoked.
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 set to the last line read in.
.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
.br
The \fIs\fR\^ubstitute command searches each addressed
line for an occurrence of the specified regular expression.
On each line in which a match is found,
all (non-overlapped) matched strings are
replaced by the
.it replacement
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
.it replacement;
`\fB.\fR' is left at the last line on which a substitution occurred.
.s2
An ampersand `&' appearing in the
.it replacement
is replaced by the string matching the regular expression on the current line.
The special meaning of `&' in this context may be
suppressed by preceding it by `\|\\'.
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
of the specified regular expression
enclosed between `\|\\(' and `\|\\)'.
When
nested parenthesized subexpressions
are present,
.it n
is determined by counting occurrences of `\|\\(' starting from the left.
.s2
A line may be split by substituting a new-line character into it.
The new-line in the
.it replacement
must be escaped by preceding it by `\|\\'.
Such substitution cannot be done as part of a
.it g
or
.it v
command list.
.s3
.lp +5 5
( \fB.\fR , \fB.\fR ) t\fIa\fR
.br
This command acts just like the
.it m
command, except that a
.it copy
of the addressed lines is placed
after address
.it a
(which may be `0');
`\fB.\fR' is left at the last line of the copy.
.s3
.lp +5 5
u
.br
This command reverses the effect of the last \fIs\fR command.
The \fIu\fR command affects only
the last
line changed by the most recent \fIs\fR command.
.s3
.lp +5 5
(1,$)\|v/regular expression/command list
.br
This command is the same as the global command \fIg\fR
except that the \fIcommand list\fR is executed
with `\fB.\fR' initially set to every line
that does
.it not
match the \fIregular expression\fR.
.s3
.lp +5 5
(1,$)\|w name
.lp +5 5
.br
(1,$)\|z name  
.br
The \fIw\fR\^rite command writes the addressed lines onto
the named file.
If the file does not exist,
it is created with mode 644 (readable by everyone, writable by you).
The remembered file name is
.it not
changed unless
\fIname\fP is the very first file name mentioned since
.it ed
was invoked.
If no file name is given,
the remembered file name, if any, is used
(see
.it e
and
.it f
commands);
`\fB.\fR' is unchanged.
If the command is successful, the number of characters written is
typed.
The
.it z
command is identical to
.it w
but, on most keyboards, the `z' key is
farther from
the `q'
key than is
the `w' key.
.s3
.lp +5 5
(1,$)\|G/regular expression/
.br
In the interactive \fIG\fR\|lobal command, the first step
is to mark every line that matches the given \fIregular expression\fR.
Then, for every such line, that line is printed, `\fB.\fP' is changed to that line, and
any
.it one
command, other than a global command (\c
.it "g, v, G,"
and
.it V\c
),
must be input.
After the execution of that command, the next marked line is printed, and so on.
A new-line acts as a null command;
an `&' causes the re-execution of the most recent command executed within
this invocation of \fIG\fR.
Note that the
commands input after the \fIG\fP command prints each marked line may
address and affect
.it any
lines in the buffer.
The
.it G
command can be terminated by an interrupt signal (\s-2ASCII\s0 \s-2DEL\s0 or \s-2BREAK\s0).
.s3
.lp +5 5
.br
P
.br
The editor will prompt with a `*' for
all subsequent commands.
This command alternately turns the mode on and off; it is
initially off.
.s3
.lp +5 5
.br
Q
.br
The editor exits without
checking if changes have been made in the buffer since the
last
.it w
or
.it z
command.
.s3
.lp +5 5
(1,$)\|V/regular expression/
.br
This command is the same as the interactive global command \fIG\fP except
that the lines that are marked during the first step are those that do
.it not
match the \fIregular expression\fR.
.s3
.lp +5 5
($)\|=
.br
The line number of the addressed line is typed;
`\fB.\fR' is unchanged by this command.
.s3
.lp +5 5
!\|\s-2UNIX\s0 command
.br
The remainder of the line after the `!' is sent
to the \s-2UNIX\s0 shell (\fIsh\fP\^(I)) to be interpreted as a command;
`\fB.\fR' is unchanged.
.s3
.lp +5 5
( \fB.\fR+1 )\|<new-line>
.br
An address alone on a line causes the addressed line to be printed.
A blank line alone is equivalent to `\fB.\fP+1p'; it is useful
for stepping through text.
.s3
.i0
If an interrupt signal (\s-2ASCII\s0 \s-2DEL\s0 or \s-2BREAK\s0) is sent,
.it ed
prints a `?' and returns to \fIits\fR command level.
.s3
Some size limitations:
512 characters per line,
256 characters per global command list,
64 characters per file name,
and 128K characters in the buffer.
The limit on the number of lines depends on the amount of user memory:
each line takes 1 word.
.s3
.it Ed
allows the user to include, in the first line of each
text file, a specification to
control the line length and the tab-to-space
conversion.
For example, <:t5,10,15s72:> sets tabs
at columns 5, 10, and 15;
it will also truncate the
.it printing
of all lines
to a length of 72 characters and warn
when a truncation has occurred.
For the specification to take effect,
the user's terminal must be in
.it echo
and
.it \-tabs
modes (see \fIstty\fP\^(I)).
Only the `t' and `s'  parameters may be used as described
in
\fIfspec\fP\^(V).
If the `s' parameter is used, all referenced
lines are checked for maximum length on file
read and write operations and on line print operations.
Appropriate diagnostics are generated.
Truncation occurs
.it only
on printing.
.s3
If the user attempts a \fIw\fR or \fIz\fR command and the
destination file system does not have enough
space available,
a diagnostic is printed with an error number (i.e. 
``\s-2NO\s0 \s-2SPACE\s0: e1''
).
.it Ed
will not perform the write.
The
.it \s-2UNIX\s0
command ``help e1'' (see \fIhelp\fP\^(I)) prints out a
full description of what to do.
.it Help
should be executed before leaving the editor (e.g.,
``!help e1'').
.sh FILES
/tmp/e#, temporary;
`#' is the process number (in octal).
.sh DIAGNOSTICS
`?' for
errors in commands;
`\s-2TMP\s0?' for temporary file (buffer) overflow;
\fIhelp\fP\^(I) error numbers in all other cases.
Commands in error should be re-entered properly.
On temporary file overflow, the buffer should be written to a file and
then an
.it e
command executed on that file.
This will re-initialize the buffer;
note that if the buffer overflows during the execution of a
command that, in the absence of the \s-2TMP\s0? diagnostic, would have
done several changes,
only some of the changes may have been done.
Help error messages are self-explanatory.
.sh "SEE ALSO"
.it "A Tutorial Introduction to the U\s-2NIX\s0 Text Editor"
by B. W. Kernighan.
.br
.it "Advanced Editing on U\s-2NIX\s0"
by B. W. Kernighan.
.sh BUGS
If the
.it s
command succeeds on (i.e., modifies)
a line that was marked by a
.it "g, v, G,"
or
.it V
command,
then that mark is effectively removed.
The editor deletes all \s-2ASCII\s0
.it null
characters whenever it reads text into the buffer.