NAME
ed - text editor

SYNOPSIS
ed [ - ] [ -x ] [ name ]

DESCRIPTION
Ed is the standard text editor.

If a name argument is given, ed simulates an e command (see below)
on the named file; that is to say, the file is read into ed’s
buffer so that it can be edited. If -x is present, an x command is
simulated first to handle an encrypted file. The optional -
suppresses printing the of explanatory output and should be used
when the standard input is an editor script.

Ed operates on a copy of any file it is editing; changes made in
the copy have no effect on the file until a w (write) command is
given. The copy of the text being edited resides in a temporary
file called the 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. Missing addresses are supplied by default.

In general, only one command may appear on a line. Certain
commands allow the addition of text to 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 specifies a set of strings of characters. A
member of this set of strings is said to be matched by the regular
expression. In the following specification for regular expressions
the word ‘character’ means any character but newline.

1. Any character except a special character matches itself.
Special characters are the regular expression delimiter plus
A . matches any character.

3. A  followed by any character except a digit or () matches that
character.

4. A nonempty string s bracketed [s] (or [^s]) matches any
character in (or not in) s. In s,  has no special meaning, and
] may only appear as the first letter. A substring a-b, with a
and b in ascending ASCII order, stands for the inclusive range
of ASCII characters.

5. A regular expression of form 1-4 followed by * matches a
sequence of 0 or more matches of the regular expression.

6. A regular expression, x, of form 1-8, bracketed matches
what x matches.

7. A  followed by a digit n matches a copy of the string that the
bracketed regular expression beginning with the nth matched.

8. A regular expression of form 1-8, x, followed by a regular
expression of form 1-7, y matches a match for x followed by a
match for y, with the x match being as long as possible while
still permitting a y match.

9. A regular expression of form 1-8 preceded by ^ (or followed by
$), is constrained to matches that begin at the left (or end at
the right) end of a line.

10. A regular expression of form 1-9 picks out the longest among
the leftmost matches in a line.

11. An empty regular expression stands for a copy of the last
regular expression encountered.

Regular expressions are used in addresses to specify lines and in
one command (see s 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.

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 is discussed under the description of the
command. Addresses are constructed as follows.

1. The character ‘.’ addresses the current line.

2. The character ‘$’ addresses the last line of the buffer.

3. A decimal number n addresses the n-th line of the buffer.

4. ‘’x’ addresses the line marked with the name x, which must be a
lower-case letter. Lines are marked with the k command
described below.

5. A regular expression enclosed in slashes ‘/’ addresses the line
found by searching forward from the current line and stopping
at the first line containing a string that matches the regular
expression. If necessary the search wraps around to the
beginning of the buffer.

6. A regular expression enclosed in queries ‘?’ addresses the line
found by searching backward from the current line and stopping
at the first line containing a string that matches the regular
expression. If necessary the search wraps around to the end of
the buffer.

7. 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.

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 ‘.-5’.

9. If an address ends with ‘+’ or ‘-’, then 1 is added (resp.
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.

10. To maintain compatibility with earlier versions of the editor,
the character ‘^’ in addresses is equivalent to ‘-’.

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. If more addresses are given than such
a command requires, the last one or two (depending on what is
accepted) are used.

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 previous address before the next
address is interpreted. This feature can be used to determine the
starting line for forward and backward searches (‘/’, ‘?’). The
second address of any two-address sequence must correspond to a
line following the line corresponding to the first address.

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, most commands 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. These suffixes may be
combined in any order.

(.)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.

(., .)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 line
preceding the deleted lines.

(., .)d
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.

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. ‘filename’ is remembered for possible use as a
default file name in a subsequent r or w command. If
‘filename’ is missing, the remembered name is used.

E filename
This command is the same as e, except that no diagnostic
results when no w has been given since the last buffer
alteration.

f filename
The filename command prints the currently remembered file
name. If ‘filename’ is given, the currently remembered file
name is changed to ‘filename’.

(1,$)g/regular expression/command list
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 ‘.’
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 ‘´. A, i, and c commands and associated
input are permitted; the ‘.’ terminating input mode may be
omitted if it would be on the last line of the command list.
The commands g and v are not permitted in the command list.

(.)i

<text>
.
This command inserts the given text before the addressed line.
‘.’ is left at the last line input, or, if there were none, at
the line before the addressed line. This command differs from
the a command only in the placement of the text.

(., .+1)j
This command joins the addressed lines into a single line;
intermediate newlines simply disappear. ‘.’ is left at the
resulting line.

( . )kx
The mark command marks the addressed line with name x, which
must be a lower-case letter. The address form ‘’x’ then
addresses this line.

(., .)l
The list command prints the addressed lines in an unambiguous
way: non-graphic characters are printed in two-digit octal,
and long lines are folded. The l command may be placed on the
same line after any non-i/o command.

(., .)ma
The move command repositions the addressed lines after the
line addressed by a. The last of the moved lines becomes the
current line.

(., .)p
The print command prints the addressed lines. ‘.’ is left at
the last line printed. The p command may be placed on the
same line after any non-i/o command.

(., .)P
This command is a synonym for p.

q The quit command causes ed to exit. No automatic write of a
file is done.

Q This command is the same as q, except that no diagnostic
results when no w has been given since the last buffer
alteration.

($)r filename
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 e and f commands). The file name is
remembered if there was no remembered file name already.
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 read in from the file.

( ., .)s/regular expression/replacement/ or,
( ., .)s/regular expression/replacement/g
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 punctuation character may be used
instead of ‘/’ to delimit the regular expression and the
replacement. ‘.’ is left at the last line substituted.

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 ‘´. The characters ‘0 where n is a digit, are
replaced by the text matched by the n-th regular subexpression
enclosed between ‘ and ‘’. When nested, parenthesized
subexpressions are present, n is determined by counting
occurrences of ‘starting from the left.

Lines may be split by substituting new-line characters into
them. The new-line in the replacement string must be escaped
by preceding it by ‘´.

(., .)ta
This command acts just like the m command, except that a copy
of the addressed lines is placed after address a (which may be
0). ‘.’ is left on the last line of the copy.

(., .)u
The undo command restores the previous content of the line
subject to the most recent substitute command.

(1, $)v/regular expression/command list
This command is the same as the global command g except that
the command list is executed with ‘.’ initially set to every
line except those matching the regular expression.

(1, $)w filename
The write command writes the addressed lines onto the given
file. If the file does not exist, it is created. The file
name is remembered if there was no remembered file name
already. If no file name is given, the remembered file name,
if any, is used (see e and f commands). ‘.’ is unchanged. If
the command is successful, the number of characters written is
printed.

(1, $)W filename
This command is the same as w, except that the addressed lines
are appended to the file.

(1, $)wq filename
This command is the same as w except that afterwards a q
command is done, exiting the editor after the file is written.

x A key string is demanded from the standard input. Later r, e
and w commands will encrypt and decrypt the text with this key
by the algorithm of crypt(1). An explicitly empty key turns
off encryption. (.+1)z or,
(.+1)zn
This command scrolls through the buffer starting at the
addressed line. 22 (or n, if given) lines are printed. The
last line printed becomes the current line. The value n is
sticky, in that it becomes the default for future z commands.

($)= The line number of the addressed line is typed. ‘.’ is
unchanged by this command.

!<shell command>
The remainder of the line after the ‘!’ is sent to sh(1) to be
interpreted as a command. ‘.’ is unchanged.

(.+1,.+1)<newline>
An address alone on a line causes the addressed line to be
printed. A blank line alone is equivalent to ‘.+1p’; it is
useful for stepping through text. If two addresses are
present with no intervening semicolon, ed prints the range of
lines. If they are separated by a semicolon, the second line
is printed.

If an interrupt signal (ASCII DEL) is sent, ed prints
‘?interrupted’ and returns to its command level.

Some size limitations: 512 characters per line, 256 characters per
global command list, 64 characters per file name, and, on mini
computers, 128K characters in the temporary file. The limit on the
number of lines depends on the amount of core: each line takes 2
words.

When reading a file, ed discards ASCII NUL characters and all
characters after the last newline. It refuses to read files
containing non-ASCII characters.

FILES
/tmp/e*
edhup: work is saved here if terminal hangs up

SEE ALSO
B. W. Kernighan, "A Tutorial Introduction to the ED Text Editor"
(see MachTen Text Processing manual)
B. W. Kernighan, "Advanced Editing on UNIX" (see MachTen Text
Processing manual)
ex(1), sed(1), crypt(1)

DIAGNOSTICS
‘?name’ for inaccessible file; ‘?self-explanatory message’ for
other errors.

To protect against throwing away valuable work, a q or e command is
considered to be in error, unless a w has occurred since the last
buffer change. A second q or e will be obeyed regardless.

BUGS
The l command mishandles DEL.
The undo command causes marks to be lost on affected lines.
The x command, -x option, and special treatment of hangups only
work on UNIX.