ED(1) MachTen Programmer’s Manual ED(1)

NAME
ed, red - text editor

SYNOPSIS
ed [-] [-Gs] [-p string] [file]

red [-] [-Gs] [-p string] [file]

DESCRIPTION
ed is a line-oriented text editor. It is used to create,
display, modify and otherwise manipulate text files. red
is a restricted ed: it can only edit files in the current
directory and cannot execute shell commands.

If invoked with a file argument, then a copy of file is
read into the editor’s buffer. Changes are made to this
copy and not directly to file itself. Upon quitting ed,
any changes not explicitly saved with a ‘w’ command are
lost.

Editing is done in two distinct modes: command and input.
When first invoked, ed is in command mode. In this mode
commands are read from the standard input and executed to
manipulate the contents of the editor buffer. A typical
command might look like:

,s/old/new/g

which replaces all occurences of the string old with new.

When an input command, such as ‘a’ (append), ‘i’ (insert)
or ‘c’ (change), is given, ed enters input mode. This is
the primary means of adding text to a file. In this mode,
no commands are available; instead, the standard input is
written directly to the editor buffer. Lines consist of
text up to and including a newline character. Input mode
is terminated by entering a single period (.) on a line.

All ed commands operate on whole lines or ranges of lines;
e.g., the ‘d’ command deletes lines; the ‘m’ command moves
lines, and so on. It is possible to modify only a portion
of a line by means of replacement, as in the example
above. However even here, the ‘s’ command is applied to
whole lines at a time.

In general, ed commands consist of zero or more line
addresses, followed by a single character command and pos-
sibly additional parameters; i.e., commands have the
structure:

[address [,address]]command[parameters]

The address(es) indicate the line or range of lines to be
affected by the command. If fewer addresses are given
than the command accepts, then default addresses are sup-
plied.

OPTIONS
-G Forces backwards compatibility. Affects the
commands ‘G’, ‘V’, ‘f’, ‘l’, ‘m’, ‘t’, and ‘!!’.

-s Suppresses diagnostics. This should be used if
ed’s standard input is from a script.

-p string
Specifies a command prompt. This may be toggled
on and off with the ‘P’ command.

file Specifies the name of a file to read. If file is
prefixed with a bang (!), then it is interpreted
as a shell command. In this case, what is read is
the standard output of file executed via sh(1).
To read a file whose name begins with a bang, pre-
fix the name with a backslash (. The default
filename is set to file only if it is not prefixed
with a bang.

LINE ADDRESSING
An address represents the number of a line in the buffer.
ed maintains a current address which is typically supplied
to commands as the default address when none is specified.
When a file is first read, the current address is set to
the last line of the file. In general, the current
address is set to the last line affected by a command.

A line address is constructed from one of the bases in the
list below, optionally followed by a numeric offset. The
offset may include any combination of digits, operators
(i.e., +, - and ^) and whitespace. Addresses are read
from left to right, and their values are computed relative
to the current address.

One exception to the rule that addresses represent line
numbers is the address 0 (zero). This means "before the
first line," and is legal wherever it makes sense.

An address range is two addresses separated either by a
comma or semicolon. The value of the first address in a
range cannot exceed the value of the the second. If only
one address is given in a range, then the second address
is set to the given address. If an n-tuple of addresses
is given where n > 2, then the corresponding range is
determined by the last two addresses in the n-tuple. If
only one address is expected, then the last address is
used.

Each address in a comma-delimited range is interpreted
relative to the current address. In a semicolon-delimited
range, the first address is used to set the current
address, and the second address is interpreted relative to
the first.

The following address symbols are recognized.

. The current line (address) in the buffer.

$ The last line in the buffer.

n The nth, line in the buffer where n is a number in
the range [0,$].

-

^ The previous line. This is equivalent to -1 and
may be repeated with cumulative effect.

-n

^n The nth previous line, where n is a non-negative
number.

+ The next line. This is equivalent to +1 and may
be repeated with cumulative effect.

+n

whitespace n
The nth next line, where n is a non-negative num-
ber. Whitespace followed by a number n is inter-
preted as +n.

,

% The first through last lines in the buffer. This
is equivalent to the address range 1,$.

; The current through last lines in the buffer.
This is equivalent to the address range .,$.

/re/ The next line containing the regular expression
re. The search wraps to the beginning of the
buffer and continues down to the current line, if
necessary. // repeats the last search.

?re? The previous line containing the regular expres-
sion re. The search wraps to the end of the
buffer and continues up to the current line, if
necessary. ?? repeats the last search.

’lc The line previously marked by a ‘k’ (mark) com-
mand, where lc is a lower case letter.

REGULAR EXPRESSIONS
Regular expressions are patterns used in selecting text.
For example, the ed command

g/string/

prints all lines containing string. Regular expressions
are also used by the ‘s’ command for selecting old text to
be replaced with new.

In addition to a specifying string literals, regular
expressions can represent classes of strings. Strings
thus represented are said to be matched by the correspond-
ing regular expression. If it is possible for a regular
expression to match several strings in a line, then the
left-most longest match is the one selected.

The following symbols are used in constructing regular
expressions:

c Any character c not listed below, including ‘{’,
’}’, ‘(’, ‘)’, ‘<’ and ‘>’, matches itself.

c A backslash-escaped character c other than ‘{’,
’}’, ‘(’, ‘)’, ‘<’, ‘>’, ‘b’, ’B’, ‘w’, ‘W’, ‘+’,
and ‘?’ matches itself.

Matches any single character.

[char-class]
Matches any single character in char-class. To
include a ‘]’ in char-class, it must be the first
character. A range of characters may be specified
by separating the end characters of the range with
a ‘-’, e.g., ‘a-z’ specifies the lower case char-
acters. The following literal expressions can
also be used in char-class to specify sets of
characters:

[:alnum:] [:cntrl:] [:lower:] [:space:]
[:alpha:] [:digit:] [:print:] [:upper:]
[:blank:] [:graph:] [:punct:] [:xdigit:]

If ‘-’ appears as the first or last character of
char-class, then it matches itself. All other
characters in char-class match themselves.

Patterns in char-class of the form:

[.col-elm.] or, [=col-elm=]

where col-elm is a collating element are inter-
preted according to locale(5) (not currently sup-
ported). See regex(3) for an explanation of these
constructs.

[^char-class]
Matches any single character, other than newline,
not in char-class. char-class is defined as
above.

^ If ‘^’ is the first character of a regular expres-
sion, then it anchors the regular expression to
the beginning of a line. Otherwise, it matches
itself.

$ If ‘$’ is the last character of a regular expres-
sion, it anchors the regular expression to the end
of a line. Otherwise, it matches itself.

re Defines a (possibly null) subexpression re.
Subexpressions may be nested. A subsequent back-
reference of the form ‘n’, where n is a number in
the range [1,9], expands to the text matched by
the nth subexpression. For example, the regular
expression ‘˙c1’ matches the string
‘abcabc’, but not ‘abcadc’. Subexpressions are
ordered relative to their left delimiter.

* Matches the single character regular expression or
subexpression immediately preceding it zero or
more times. If ’*’ is the first character of a
regular expression or subexpression, then it
matches itself. The ‘*’ operator sometimes yields
unexpected results. For example, the regular
expression ‘b*’ matches the beginning of the
string ‘abbb’, as opposed to the substring ‘bbb’,
since a null match is the only left-most match.

n,m
n,
n Matches the single character regular expression or
subexpression immediately preceding it at least n
and at most m times. If m is omitted, then it
matches at least n times. If the comma is also
omitted, then it matches exactly n times. If any
of these forms occurs first in a regular expres-
sion or subexpression, then it is interpreted lit-
erally (i.e., the regular expression ‘2’
matches the string ‘{2}’, and so on).

<
> Anchors the single character regular expression or
subexpression immediately following it to the
beginning (<) or ending (>) of a word, i.e., in
ASCII, a maximal string of alphanumeric charac-
ters, including the underscore (_).

The following extended operators are preceded by a back-
slash ( to distinguish them from traditional ed syntax.

`
´ Unconditionally matches the beginning (`) or end-
ing (´) of a line.

expression or subexpression immediately preceding
it. For example, the regular expression
‘a[bd] ‘ac’. If expressions or subexpression, then it matches a
literal ‘?’.

+ Matches the single character regular expression or
subexpression immediately preceding it one or more
times. So the regular expression ‘a+’ is short-
hand for ‘aa*’. If + occurs at the beginning of
a regular expression or subexpression, then it
matches a literal ‘+’.

Matches the beginning or ending (null string) of a e l
word. Thus the regular expression ‘l o
equivalent to ‘<hello>’. However, ‘
valid regular expression whereas ‘<>’ is not.

0 Matches (a null string) inside a word.

0 Matches any character in a word.

W Matches any character not in a word.

COMMANDS
All ed commands are single characters, though some require
additonal parameters. If a command’s parameters extend
over several lines, then each line except for the last
must be terminated with a backslash (.

In general, at most one command is allowed per line. How-
ever, most commands accept a print suffix, which is any of
‘p’ (print), ‘l’ (list) , or ‘n’ (enumerate), to print the
last line affected by the command.

An interrupt (typically ^C) has the effect of aborting the
current command and returning the editor to command mode.

ed recognizes the following commands. The commands are
shown together with the default address or address range
supplied if none is specified (in parenthesis).

(.)a Appends text to the buffer after the addressed
line, which may be the address 0 (zero). Text is
entered in input mode. The current address is set
to last line entered.

(.,.)c Changes lines in the buffer. The addressed lines
are deleted from the buffer, and text is appended
in their place. Text is entered in input mode.
The current address is set to last line entered.

(.,.)d Deletes the addressed lines from the buffer. If
there is a line after the deleted range, then the
current address is set to this line. Otherwise the
current address is set to the line before the
deleted range.

e file Edits file, and sets the default filename. If
file is not specified, then the default filename
is used. Any lines in the buffer are deleted
before the new file is read. The current address
is set to the last line read.

e !command
Edits the standard output of ‘!command’, (see
!command below). The default filename is
unchanged. Any lines in the buffer are deleted
before the output of command is read. The current
address is set to the last line read.

E file Edits file unconditionally. This is similar to
the e command, except that unwritten changes are
discarded without warning. The current address is
set to the last line read.

f file Sets the default filename to file. If file is not
specified, then the default unescaped filename is
printed.

(1,$)g/re/command-list
Applies command-list to each of the addressed
lines matching a regular expression re. The cur-
rent address is set to the line currently matched
before command-list is executed. At the end of
the ‘g’ command, the current address is set to the
last line affected by command-list.

Each command in command-list must be on a separate
line, and every line except for the last must be
terminated by a backslash (. Any commands are
allowed, except for ‘g’, ‘G’, ‘v’, and ‘V’. A
newline alone in command-list is equivalent to a
‘p’ command.

(1,$)G/re/
Interactively edits the addressed lines matching a
regular expression re. For each matching line,
the line is printed, the current address is set,
and the user is prompted to enter a command-list.
At the end of the ‘G’ command, the current address
is set to the last line affected by (the last)
command-list.

The format of command-list is the same as that of
the ‘g’ command. A newline alone acts as a null
command list. A single ‘&’ repeats the last non-
null command list.

H Toggles the printing of error explanations. By
default, explanations are not printed. It is rec-
ommended that ed scripts begin with this command
to aid in debugging.

h Prints an explanation of the last error.

(.)i Inserts text in the buffer before the current
line. Text is entered in input mode. The current
address is set to the last line entered.

(.,.+1)j
Joins the addressed lines. The addressed lines
are deleted from the buffer and replaced by a sin-
gle line containing their joined text. The cur-
rent address is set to the resultant line.

(.)klc Marks a line with a lower case letter lc. The
line can then be addressed as ’lc (i.e., a single
quote followed by lc ) in subsequent commands.
The mark is not cleared until the line is deleted
or otherwise modified.

(.,.)l Prints the addressed lines unambiguously. If
invoked from a terminal, ed pauses at the end of
each page until a newline is entered. The current
address is set to the last line printed.

(.,.)m(.)
Moves lines in the buffer. The addressed lines
are moved to after the right-hand destination
address, which may be the address 0 (zero). The
current address is set to the last line moved.

(.,.)n Prints the addressed lines along with their line
numbers. The current address is set to the last
line printed.

(.,.)p Prints the addressed lines. If invoked from a
terminal, ed pauses at the end of each page until
a newline is entered. The current address is set
to the last line printed.

P Toggles the command prompt on and off. Unless a
prompt was specified by with command-line option
-p string, the command prompt is by default turned
off.

q Quits ed.

Q Quits ed unconditionally. This is similar to the
q command, except that unwritten changes are dis-
carded without warning.

($)r file
Reads file to after the addressed line. If file
is not specified, then the default filename is
used. If there was no default filename prior to
the command, then the default filename is set to
file. Otherwise, the default filename is
unchanged. The current address is set to the last
line read.

($)r !command
Reads to after the addressed line the standard
output of ‘!command’, (see the !command below).
The default filename is unchanged. The current
address is set to the last line read.

(.,.)s/re/replacement/
(.,.)s/re/replacement/g
(.,.)s/re/replacement/n
Replaces text in the addressed lines matching a
regular expression re with replacement. By
default, only the first match in each line is
replaced. If the ‘g’ (global) suffix is given,
then every match to be replaced. The ‘n’ suffix,
where n is a postive number, causes only the nth
match to be replaced. It is an error if no sub-
stitutions are performed on any of the addressed
lines. The current address is set the last line
affected.

re and replacement may be delimited by any charac-
ter other than space and newline (see the ‘s’ com-
mand below). If one or two of the last delimiters
is omitted, then the last line affected is printed
as though the print suffix ‘p’ were specified.

An unescaped ‘&’ in replacement is replaced by the
currently matched text. The character sequence
‘m’, where m is a number in the range [1,9], is
replaced by the mth backreference expression of
the matched text. If replacement consists of a
single ‘%’, then replacement from the last substi-
tution is used. Newlines may be embedded in
replacement if they are escaped with a backslash
(.

(.,.)s Repeats the last substitution. This form of the
‘s’ command accepts a count suffix ‘n’, or any
combination of the characters ‘r’, ‘g’, and ‘p’.
If a count suffix ‘n’ is given, then only the nth
match is replaced. The ‘r’ suffix causes the reg-
ular expression of the last search to be used
instead of the that of the last substitution. The
‘g’ suffix toggles the global suffix of the last
substitution. The ‘p’ suffix toggles the print
suffix of the last substitution The current
address is set to the last line affected.

(.,.)t(.)
Copies (i.e., transfers) the addressed lines to
after the right-hand destination address, which
may be the address 0 (zero). The current address
is set to the last line copied.

u Undoes the last command and restores the current
address to what it was before the command. The
global commands ‘g’, ‘G’, ‘v’, and ‘V’. are
treated as a single command by undo. ‘u’ is its
own inverse.

(1,$)v/re/command-list
Applies command-list to each of the addressed
lines not matching a regular expression re. This
is similar to the ‘g’ command.

(1,$)V/re/
Interactively edits the addressed lines not match-
ing a regular expression re. This is similar to
the ‘G’ command.

(1,$)w file
Writes the addressed lines to file. Any previous
contents of file is lost without warning. If
there is no default filename, then the default
filename is set to file, otherwise it is
unchanged. If no filename is specified, then the
default filename is used. The current address is
unchanged.

(1,$)wq file
Writes the addressed lines to file, and then exe-
cutes a ‘q’ command.

(1,$)w !command
Writes the addressed lines to the standard input
of ‘!command’, (see the !command below). The
default filename and current address are
unchanged.

(1,$)W file
Appends the addressed lines to the end of file.
This is similar to the ‘w’ command, expect that
the previous contents of file is not clobbered.
The current address is unchanged.

(.)x Copies (puts) the contents of the cut buffer to
after the addressed line. The current address is
set to the last line copied.

(.,.)y Copies (yanks) the addressed lines to the cut
buffer. The cut buffer is overwritten by subse-
quent ‘y’, ‘s’, ‘j’, ‘d’, or ‘c’ commands. The
current address is unchanged.

(.+1)zn Scrolls n lines at a time starting at addressed
line. If n is not specified, then the current
window size is used. The current address is set
to the last line printed.

!command
Executes command via sh(1). If the first charac-
ter of command is ‘!’, then it is replaced by text
of the previous ‘!command’. ed does not process
command for backslash ( escapes. However, an
unescaped ‘%’ is replaced by the default filename.
When the shell returns from execution, a ‘!’ is
printed to the standard output. The current line
is unchanged.

(.,.)# Begins a comment; the rest of the line, up to a
newline, is ignored. If a line address followed
by a semicolon is given, then the current address
is set to that address. Otherwise, the current
address is unchanged.

($)= Prints the line number of the addressed line.

(.+1)newline
Prints the addressed line, and sets the current
address to that line.

FILES
/tmp/ed.* Buffer file
ed.hup The file to which ed attempts to write
the buffer if the terminal hangs up.

SEE ALSO
vi(1), sed(1), regex(3), sh(1).

USD:12-13

B. W. Kernighan and P. J. Plauger, Software Tools in Pas-
cal , Addison-Wesley, 1981.

LIMITATIONS
ed processes file arguments for backslash escapes, i.e.,
in a filename, any characters preceded by a backslash (
are interpreted literally.

If a text (non-binary) file is not terminated by a newline
character, then ed appends one on reading/writing it. In
the case of a binary file, ed does not append a newline on
reading/writing.

per line overhead: 4 ints

DIAGNOSTICS
When an error occurs, if ed’s input is from a regular file
or here document, then it exits, otherwise it prints a ‘?’
and returns to command mode. An explanation of the last
error can be printed with the ‘h’ (help) command.

Attempting to quit ed or edit another file before writing
a modified buffer results in an error. If the command is
entered a second time, it succeeds, but any changes to the
buffer are lost.

ed exits with 0 if no errors occurred; otherwise >0.

MachTen 10 November 1994 10