V1/man/man1/ed.1
11/3/71 ED (I)
NAME ed -- editor
SYNOPSIS ed [ name ]
DESCRIPTION ed is the standard text editor. ed is based on QED
[reference] but is fully if succinctly described here.
Differences between ed and QED are also noted to simplify
the transition to the less powerful editor.
If the optional argument is given, simulates an e command
on the named file; that is to say, the file is read into
ed's buffer so that it can be edited.
ed operates on a copy of any file it is editing; changes
made in the copy have no effect on the file until an
explicit write (w) command is given. The copy of the text
being edited resides in a temporary file called the buffer.
There is only one buffer.
Commands to ed have a simple and regular structure: zero or
more addresses followed by a single character 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.
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 ed is accepting
text, it is said to be in input mode. In this mode, no
commands are recognized; all input is merely collected.
Input mode is left by typing a period (.) alone at the
beginning of a line.
ed supports a limited form of regular expression notation.
A regular expression is an expression which specifies a set
of strings of characters. A member of this set of strings
is said to be matched by the regular expression. The
regular expressions allowed by are constructed as follows:
1 . An ordinary character (not one of those
discussed below) is a regular expression
and matches that character.
2. A circumflex (^) at the beginning of a regular
expression matches the null character
at the beginning of a line.
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3. A currency symbol ($) at the end of a regular
expression matches the null character
at the end of a line.
4. A period (.) matches any character but a new--line
character.
5. A regular expression followed by an asterisk (*)
matches any number of adjacent occurrences
(including zero) of the regular expression it
follows.
6. A string of characters enclosed in square brackets
([]) matches any character in the string but no
others. If, however, the first character of the
string is a circumflex (^) the regular expression
matches any character but new--line and the
characters in the string.
7. The concatenation of regular expressions is a
regular expression which matches the concatenation
of the strings matched by the components of the
regular expression.
8. The null regular expression standing alone is
equivalent to the last regular expression
encountered.
Regular expressions are used in addresses to specify lines
and in one command (s, see below) to specify a portion of a
line which is to be replaced.
If it is desired to use one of the regular expression
metacharacters as an ordinary character, that character may
be preceded by "\". This also applies to the character
bounding the regular expression (often "/") and to \
itself.
Addresses are constructed as follows. To understand
addressing in ed it is necessary to know that at any time
there is a current line. Generally speaking, the current
line is the last line affected by a command; however, the
exact effect on the current line by each command is
discussed under the description of the command.
1. The character "." addresses the current line.
2. The character "$" addresses the last line of the
buffer.
3. A decimal number n addresses the nth line
of the buffer.
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4. 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.
5. 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 found containing a string matching the
regular expression. If necessary the search wraps
around to the end of the buffer.
6. An address followed by a plus sign "+" or a minus
sign "--" followed by a decimal number specifies
that address plus (resp. minus) the indicated
number of lines. The plus sign may be omitted.
Commands may require zero, one, or two addresses. Commands
which require no addresses regard the presence of an
address as an error. Commands which require the presence of
one address all assume a default address (often ".") but if
given more than one address ignore any extras and use the
last given. Commands which require two addresses have
defaults in the case of zero or one address but use the
last two if more than two are given.
Addresses are separated from each other typically by a
comma (,). They may also be separated by a semicolon ";".
In this case the current line is set to the the previous
address before the next address is interpreted. This
feature is used to control the starting line for forward
and backward searches ("/", "?").
In the following list of ed 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.
As mentioned, it is generally illegal for more than one
command to appear on a line. However, any command may be
suffixed by "p" (for "print ). In that case, the current
line is printed after the command is complete.
In any two--address command, it is illegal for the
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first address to lie after the second address.
(.)a
<text>
.
The append command reads the given text and appends
it after the addressed line "."
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. (NOTE: the default address
differs from that of QED.)
(.,.c)
(text>
.
The change command deletes the addressed lines, then
accepts input text which replaces these lines. "."
is left at the last line input; if there were none,
it is left at the first line not changed.
(.,.)d
The delete command deletes the addressed lines from
the buffer. "." is left at the first line not
deleted.
e filename
The edit command causes the entire contents of the
buffer to be deleted. and then the named file to be
read in. "." is set to the last line of the buffer.
The number of characters read is typed.
(1 ,s)g/regular expression/command
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 is executed with "." set to that line. The
repeated command cannot be a, g, i, or c.
(.)i
<text>
.
This command inserts given text before the addressed
line. "." is left at the last line input; if there
were none, at the addressed line. This command
differs from the a command only in the placement of
the text.
(.,.)l
The list command prints the addressed lines
in an unambiguous way. Non--printing
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characters are over--struck as follows:
char prints
bs [overstruct - \]
tab [overstruct - >]
ret [overstruct - <]
SI [overstruct I -]
SO [overstruct O -]
All characters preceded by a prefix (ESC) character
are printed over--struck with without the prefix.
Long lines are folded with the sequence \newline.
(.,.p)
The print command prints the addressed lines. . is
left at the last line printed
q
The quit command causes ed to exit. No
automatic write of a file is done.
($)r filename
The read command reads in the given file after the
addressed line. If no file name is given, the file
last mentioned in e, r, or w commands is read.
Address "0" is legal for r and causes the file to
be read at the beginning of the buffer. If the read
is successful, the number of characters read is
typed."." is left at the last line of the file.
(.,.)s/regular expression/replacement/
The substitute command searches each addressed line for
an occurence of the specified regular expression.
On each line in which a match is found, the first
(and only first, compare QED) matched string is
replaced by the replacement specified. It is an
error for the substitution to fail on all addressed
lines. Any character other than space or new--line
may be used instead of "/" to delimit the regular
expression and the replacement. "." is left at the
last line substituted.
The ampersand "&" appearing in the replacement is
replaced by the regular expression that was
matched. The special meaning of "&" in this context
may be suppressed by preceding it by "\".
(1,$)w filename
The write command writes the addressed lines onto
the given file. If no file name is given, the file
last named in e, r, or w
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commands is written. "." is unchanged. If the
command is successful, the number of characters
written is typed. The line number of the addressed
line is typed. . is unchanged by this command.
($)=
The line number of the addressed line is typed. "."
is unchanged by this command.
!UNIX command
The remainder of the line after the "!" is sent to
UNIX to be interpreted as a command. "."is
unchanged.
(newline>
A blank line alone is equivalent to ".+lp";
it is useful for stepping through text.
Ed can edit at most 1500 lines and the maximum size of a
line is 256 characters, The differences between ed and QED
are:
1. There is no \f character; input mode is left by
typing . alone on a line.
2. There is only one buffer and hence no stream
directive.
3. The commands are limited to:
a c d e g i l p q r s w = !
where e is new.
4. The only special characters in regular expressions
are:
* ^ $ [ .
which have the usual meanings. However, "^" and "$"
are only effective if they are the first or last
character respectively of the regular expression.
Otherwise suppression of special meaning is done by
preceding the character by "\ , which is not
otherwise special.
5. In the substitute command, only the leftmost
occurrence of the matched regular
expression is substituted.
7. The a command has a different default address.
FILES /tmp/etma, etmb, ... temporary
/etc/msh is used to implement the "!" command.
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SEE ALSO
DIAGNOSTICS ? for any error
BUGS ed is used as the shell for the editing system. It has the
editing system UID built in and if invoked under this UID
will give slightly different responses. This is a little
kludgy.
OWNER ken