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NAME
ed, red - text editor
SYNTAX
ed [-] [-pstring] [file]
red [-] [file]
DESCRIPTION
The ed text editor is the standard text editor. If the file
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. The optional - suppresses
the printing of character counts by e, r, and w commands, of
diagnostics from e and q commands, and of the ! prompt after
a !shell command. The -p option allows the user to specify
a prompt string. The ed text editor operates on a copy of
the file it is editing; changes made to 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. There is only one buffer.
The red text editor is a restricted version of ed. It only
allows editing of files in the current directory. It prohi-
bits executing shell commands via !shell command. Attempts
to bypass these restrictions result in an error message
(restricted shell).
NOTE
While inputting text, tab characters are expanded
to every eighth column as is the default.
Commands to ed have a simple and regular structure: zero,
one, or two addresses followed by a single-character com-
mand, 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 frequently be omitted.
In general, only one command appears 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 input mode, no
commands are recognized; all input is merely collected.
Input mode is exited by typing a period (.) alone at the
beginning of a line.
The ed text editor supports a limited form of regular
expression notation; regular expressions are used in
addresses to specify lines and in some commands (for exam-
ple, s) to specify portions of a line that are to be substi-
tuted. A regular expression (RE) specifies a set of charac-
ter strings. A member of this set of strings is said to be
matched by the RE. The REs allowed by ed are constructed as
follows:
The following one-character REs match a single character:
1.1 An ordinary character (not one of those discussed in
1.2 below) is a one-character RE that matches itself.
1.2 A backslash (\) followed by any special character is
a one-character RE that matches the special character
itself. The special characters are:
a. ., *, [, and \ (period, asterisk, left square
bracket, and backslash, respectively), which
are always special, except when they appear
within square brackets ([]; see 1.4 below).
b. ^ (caret or circumflex), which is special at
the beginning of an entire RE (see 3.1 and 3.2
below), or when it immediately follows the left
of a pair of square brackets ([]) (see 1.4
below).
c. $ (currency symbol), which is special at the
end of an entire RE (see 3.2 below).
d. The character used to bound (that is, delimit)
an entire RE, which is special for that RE (for
example, see how slash (/) is used in the g
command, below.)
1.3 A period (.) is a one-character RE that matches any
character except new-line.
1.4 A non-empty string of characters enclosed in square
brackets ([]) is a one-character RE that matches any
one character in that string. If, however, the first
character of the string is a circumflex (^), the
one-character RE matches any character except new-
line and the remaining characters in the string. The
^ has this special meaning only if it occurs first in
the string. The minus (-) may be used to indicate a
range of consecutive ASCII 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 right
square bracket (]) does not terminate such a string
when it is the first character within it (after an
initial ^, if any). For example, []a-f] matches
either a right square bracket (]) or one of the
letters a through f inclusive. The four characters
listed in 1.2.a above stand for themselves within
such a string of characters.
The following rules may be used to construct REs from one-
character REs:
2.1 A one-character RE is a RE that matches whatever the
one-character RE matches.
2.2 A one-character RE followed by an asterisk (*) is a
RE that matches zero or more occurrences of the one-
character RE. If there is any choice, the longest
leftmost string that permits a match is chosen.
2.3 A one-character RE followed by \{m\}, \{m,\}, or
\{m,n\} is a RE that matches a range of occurrences
of the one-character RE. The values of m and n must
be non-negative integers less than 256; \{m\} matches
exactly m occurrences; \{m,\} matches at least m
occurrences; \{m,n\} matches any number of
occurrences between m and n inclusive. Whenever a
choice exists, the RE matches as many occurrences as
possible.
2.4 The concatenation of REs is a RE that matches the
concatenation of the strings matched by each com-
ponent of the RE.
2.5 A RE enclosed between the character sequences \( and
\) is a RE that matches whatever the unadorned RE
matches.
2.6 The expression \n matches the same string of charac-
ters as was matched by an expression enclosed between
\( and \) earlier in the same RE. Here n is a digit;
the sub-expression specified is that beginning with
the n-th occurrence of \( counting from the left.
For example, the expression ^\(.*\)\1$ matches a line
consisting of two repeated appearances of the same
string.
Finally, an entire RE may be constrained to match only an
initial segment or final segment of a line (or both):
3.1 A circumflex (^) at the beginning of an entire RE
constrains that RE to match an initial segment of a
line.
3.2 A currency symbol ($) at the end of an entire RE con-
strains that RE to match a final segment of a line.
The construction ^entire RE$ constrains the entire RE to
match the entire line.
The null RE (for example, //) is equivalent to the last RE
encountered. See also the last paragraph before FILES
below.
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; the
exact effect on the current line is discussed under the
description of each 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 mark name char-
acter x, which must be a lower-case letter. Lines
are marked with the k command described below.
5. A RE enclosed by slashes (/) addresses the first line
found by searching forward from the line following
the current line toward the end of the buffer and
stopping at the first line containing a string match-
ing the RE. If necessary, the search wraps around to
the beginning of the buffer and continues up to and
including the current line, so that the entire buffer
is searched. See also the last paragraph before
FILES below.
6. A RE enclosed in question marks (?) addresses the
first line found by searching backward from the line
preceding the current line toward the beginning of
the buffer and stopping at the first line containing
a string matching the RE. If necessary, the search
wraps around to the end of the buffer and continues
up to and including the current line. See also the
last paragraph before FILES below.
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.
8. If an address begins with + or -, the addition or
subtraction is taken with respect to the current
line. For example, -5 is understood to mean .-5.
9. If an address ends with + or -, then 1 is added to or
subtracted from the address, respectively. As a
consequence of this rule and of rule 8 immediately
above, the address - refers to the line preceding the
current line. (To maintain compatibility with ear-
lier versions of the editor, the character ^ in
addresses is entirely equivalent to -.) Moreover,
trailing + and - characters have a cumulative effect,
so -- refers to the current line less 2.
10. For convenience, a comma (,) stands for the address
pair 1,$, while a semicolon (;) stands for the pair
.,$.
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.
Typically, addresses are separated from each other by a
comma (,). They may also be separated by a semicolon (;).
In the latter case, the current line (.) is set to the first
address, and only then is the second address calculated.
This feature can be used to determine the starting line for
forward and backward searches (see rules 5. and 6. 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.
In the following list of ed commands, the default addresses
are shown in parentheses. The parentheses are not part of
the address; they show that the given addresses are the
default.
It is generally illegal for more than one command to appear
on a line. However, any command (except e, f, r, or w) may
be suffixed by l, n or p, in which case the current line is
either listed, numbered or printed, respectively, as dis-
cussed below under the l, n and p commands.
(.)a
<text>
. The append command reads the given text
and appends it after the addressed line;
. is left at the last inserted line, or,
if there were none, at the addressed
line. Address 0 is legal for this com-
mand: it causes the ``appended'' text to
be placed at the beginning of the
buffer. The maximum number of charac-
ters that may be entered from a terminal
is 256 per line (including the new line
character).
(.)c
<text>
.
The change command deletes the addressed
lines, then accepts input text that
replaces these lines; . is left at the
last line input, or, if there were none,
at the first line that was not deleted.
(.,.)d
The delete 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.
e file
The edit command causes the entire con-
tents of the buffer to be deleted, and
then the named file to be read in; . is
set to the last line of the buffer. If
no file name is given, the currently-
remembered file name, if any, is used
(see the f command). The number of
characters read is typed; file is remem-
bered for possible use as a default file
name in subsequent e, r, and w commands.
If file is replaced by !, the rest of
the line is taken to be a shell, sh(1),
command whose output is to be read.
Such a shell command is not remembered
as the current file name. See also
DIAGNOSTICS below.
E file
The edit command is like e, except that
the editor does not check to see if any
changes have been made to the buffer
since the last w command.
f file
If file is given, the file-name command
changes the currently-remembered file
name to file; otherwise, it prints the
currently-remembered file name.
(1,$)g/RE/command list
In the global command, the first step is
to mark every line that matches the
given RE. Then, for every such line,
the given command list is executed with
. initially set to that line. A single
command or the first of a list of com-
mands appears on the same line as the
global command. All lines of a multi-
line list except the last line must be
ended with a \; a, i, and c commands and
associated input are permitted; the .
terminating input mode may be omitted if
it would be the last line of the command
list. An empty command list is
equivalent to the p command. The g, G,
v, and V commands are not permitted in
the command list. See also RESTRICTIONS
and the last paragraph before FILES
below.
(1,$)G/RE/
In the interactive Global command, the
first step is to mark every line that
matches the given RE. Then, for every
such line, that line is printed, . is
changed to that line, and any one com-
mand (other than one of the a, c, i, g,
G, v, and V commands) may be input and
is executed. 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 the current invocation
of G. Note that the commands input as
part of the execution of the G command
may address and affect any lines in the
buffer. The G command can be terminated
by an interrupt signal (ASCII DEL or
BREAK).
h
The help command gives a short error
message that explains the reason for the
most recent ? diagnostic.
H
The help command causes ed to enter a
mode in which error messages are printed
for all subsequent ? diagnostics. It
will also explain the previous ? if
there was one. The H command alter-
nately turns this mode on and off; it is
initially off.
(.)i
<text>
.
The insert command inserts the given
text before the addressed line; . is
left at the last inserted line, or, if
there were none, at the addressed line.
This command differs from the a command
only in the placement of the input text.
Address 0 is not legal for this command.
The maximum number of characters that
may be entered from a terminal is 256
per line (including the new line charac-
ter).
(.,.+1)j
The join command joins contiguous lines
by removing the appropriate new-line
characters. If exactly one address is
given, this command does nothing.
(.)kx
The mark command marks the addressed
line with name x, which must be a
lower-case letter. The address 'x then
addresses this line; . is unchanged.
(.,.)l
The list command prints the addressed
lines in an unambiguous way: a few non-
printing characters (for example, tab,
backspace) are represented by (hope-
fully) mnemonic overstrikes, all other
non-printing characters are printed in
octal, and long lines are folded. An l
command may be appended to any other
command other than e, f, r, or w.
(.,.)ma
The B. move command repositions the
addressed line(s) after the line
addressed by a. Address 0 is legal for a
and causes the addressed line(s) to be
moved to the beginning of the file; it
is an error if address a falls within
the range of moved lines; . is left at
the last line moved.
(.,.)n
The number command prints the addressed
lines, preceding each line by its line
number and a tab character; . is left at
the last line printed. The n command
may be appended to any other command
other than e, f, r, or w.
(.,.)p
The print command prints the addressed
lines; . is left at the last line
printed. The p command may be appended
to any other command other than e, f, r,
or w; for example, dp deletes the
current line and prints the new current
line.
P
The editor will prompt with a * for all
subsequent commands. The P command
alternately turns this mode on and off;
it is initially off.
q
The quit command causes ed to exit. No
automatic write of a file is done (but
see DIAGNOSTICS below).
Q
The editor exits without checking if
changes have been made in the buffer
since the last w command.
($)r file
The read command reads in the given file
after the addressed line. If no file
name is given, the currently-remembered
file name, if any, is used (see e and f
commands). The currently-remembered
file name is not changed unless file is
the very first file name mentioned since
ed was invoked. Address 0 is legal for
r and causes the file to be read at the
beginning of the buffer. If the read is
successful, the number of characters
read is typed; . is set to the last line
read in. If file is replaced by !, the
rest of the line is taken to be a shell
(sh(1)) command whose output is to be
read. For example, "$r !ls" appends
current directory to the end of the file
being edited. Such a shell command is
not remembered as the current file name.
(.,.)s/RE/replacement/ or
(.,.)s/RE/replacement/g
The substitute command searches each
addressed line for an occurrence of the
specified RE. In each line in which a
match is found, all (non-overlapped)
matched strings are replaced by the
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 RE and the
replacement; . is left at the last line
on which a substitution occurred. See
also the last paragraph before FILES
below.
An ampersand (&) appearing in the
replacement is replaced by the string
matching the RE on the current line.
The special meaning of & in this context
may be suppressed by preceding it by \.
As a more general feature, the charac-
ters \n, where n is a digit, are
replaced by the text matched by the n-th
regular subexpression of the specified
RE enclosed between \( and \). When
nested parenthesized subexpressions are
present, n is determined by counting
occurrences of \( starting from the
left. When the character % is the only
character in the replacement, the
replacement used in the most recent sub-
stitute command is used as the replace-
ment in the current substitute command.
The % loses its special meaning when it
is in a replacement string of more than
one character or is preceded by a \.
A line may be split by substituting a
new-line character into it. The new-
line in the replacement must be escaped
by preceding it by \. Such substitution
cannot be done as part of a g or v com-
mand list.
(.,.)ta
This command acts just like the m com-
mand, except that a copy of the
addressed lines is placed after address
a (which may be 0); . is left at the
last line of the copy.
u
The undo command nullifies the effect of
the most recent command that modified
anything in the buffer, namely the most
recent a, c, d, g, i, j, m, r, s, t, v,
G, or V command.
(1,$)v/RE/command list
This command is the same as the global
command g except that the command list
is executed with . initially set to
every line that does not match the RE.
(1,$)V/RE/
This command is the same as the interac-
tive global command G except that the
lines that are marked during the first
step are those that do not match the RE.
(1,$)w file
The write command writes the addressed
lines into the named file. If the file
does not exist, it is created with mode
666 (readable and writable by everyone),
unless your umask setting (see sh(1))
dictates otherwise. The currently-
remembered file name is not changed
unless file is the very first file name
mentioned since ed was invoked. If no
file name is given, the currently-
remembered file name, if any, is used
(see e and f commands); . is unchanged.
If the command is successful, the number
of characters written is typed. If file
is replaced by !, the rest of the line
is taken to be a shell (sh(1)) command
whose standard input is the addressed
lines. Such a shell command is not
remembered as the current file name.
($)=
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 the UNIX System shell (sh(1)) to
be interpreted as a command. Within the
text of that command, the unescaped
character % is replaced with the remem-
bered file name; if a ! appears as the
first character of the shell command, it
is replaced with the text of the previ-
ous shell command. Thus, !! will repeat
the last shell command. If any expan-
sion is performed, the expanded line is
echoed; . is unchanged.
(.+1)<new-line>
An address alone on a line causes the
addressed line to be printed. A new-
line alone is equivalent to .+1p; it is
useful for stepping forward through the
buffer.
If an interrupt signal (ASCII DEL or BREAK) is sent, ed
prints a ? and returns to its command level.
Some size limitations: 512 characters per line, 256 charac-
ters 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.
When reading a file, ed discards ASCII NUL characters and
all characters after the last new-line. Files (for example,
a.out) that contain characters not in the ASCII set (bit 8
on) cannot be edited by ed.
If the closing delimiter of a RE or of a replacement string
(for example, /) would be the last character before a new-
line, that delimiter may be omitted, in which case the
addressed line is printed. The following pairs of commands
are equivalent:
s/s1/s2 s/s1/s2/p
g/s1 g/s1/p
?s1 ?s1?
RESTRICTIONS
A ! command cannot be subject to a g or a v command.
The ! command and the ! escape from the e, r, and w commands
cannot be used if the the editor is invoked from a res-
tricted shell. For further information, see sh(1).
The sequence \n in a RE does not match a new-line character.
The l command mishandles DEL.
DIAGNOSTICS
? for command errors.
?file for an inaccessible file.
(use the help and Help commands for detailed
explanations).
If changes have been made in the buffer since the last w
command that wrote the entire buffer, ed warns the user if
an attempt is made to destroy ed's buffer via the e or q
commands: it prints ? and allows one to continue editing. A
second e or q command at this point will take effect. The -
command-line option inhibits this feature.
FILES
/tmp/e# temporary; # is the process number.
ed.hup work is saved here if the terminal is hung up.
SEE ALSO
grep(1), sed(1), sh(1), stty(1),
