\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename ed.info
@settitle GNU @code{ed} reference manual
@finalout
@setchapternewpage odd
@c %**end of header

@ifinfo
This file documents the @code{ed} command, which has the purpose of
editing text files.

Copyright (C) 1993 by the Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Foundation.
@end ifinfo

@titlepage
@title GNU ed, version 0.2
@subtitle A text editor
@subtitle Edition 0.2, November 1994
@author by Andrew Moore

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1993, 1994 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions,
except that this permission notice may be stated in a translation approved
by the Foundation.
@end titlepage

@ifinfo
@node Top, Intro, (dir), (dir)
@top

This info file documents the @code{ed} text editor, as of release 0.2.
You may find in this document:

@end ifinfo

@menu
* Intro::                       An introduction to line editing with  @code{ed}
* Invoking ed::                 GNU @code{ed} command-line options
* Line addressing::             Specifying lines/ranges in the buffer
* Regular expressions::         Patterns for selecting text
* Commands::                    Commands recognized by GNU @code{ed}
* Limitations::                 Intrinsic limits of GNU @code{ed}
* Diagnostics::                 GNU @code{ed} error handling
@end menu

@node Intro, Invoking ed, Top, Top
@chapter Intro

@code{ed} is a line-oriented text editor.  It is used to create,
display, modify and otherwise manipulate text files, both interactively
and via shell scripts.  A restricted version of @code{ed}, @code{red},
can only edit files in the current directory and cannot execute shell
commands.  @code{ed} is the ``standard'' text editor in the sense that
it is the original editor for Unix, and thus widely available.  For
most purposes, however, it is superceded by full-screen editors such as
Emacs and Vi.

The sample sessions below illustrate some basic concepts of line editing
with @code{ed}.  We begin by creating a file, @samp{sonnet}, with some
help from Shakespeare.  As with the shell, all input to @code{ed} must
be followed by a @key{newline} character.  Comments begin with a @samp{#}.

@example
$ ed
# The `a' command is for appending text to the editor buffer.
a
No more be grieved at that which thou hast done.
Roses have thorns, and filvers foutians mud.
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
.
# Entering a single period on a line returns @code{ed} to command mode.
# Now write the buffer to the file @samp{sonnet} and quit:
w sonnet
183
# @code{ed} reports the number of characters written.
q
$ ls -l
total 2
-rw-rw-r--    1 alm           183 Nov 10 01:16 sonnet
$
@end example

Editing with @code{ed} is done in two distinct
modes: @dfn{command} and @dfn{input}.  When first invoked, @code{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.  When an
input command, such as @samp{a} (append), @samp{i} (insert) or @samp{c}
(change), is given, @code{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. A @dfn{line} consists of the text up to and including a
@key{newline} character.  Input mode is terminated by
entering a single period (@samp{.}) on a line.

In the next example, some typos are corrected in the file @samp{sonnet}.

@example
$ ed sonnet
183
# Begin by printing the buffer to the terminal with the @samp{p} command.
# The `,' means ``all lines.''
,p
No more be grieved at that which thou hast done.
Roses have thorns, and filvers foutians mud.
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
# Select line 2 for editing.
2
Roses have thorns, and filvers foutians mud.
# Use the substitute command, @samp{s}, to replace `filvers' with `silver',
# and print the result.
s/filvers/silver/p
Roses have thorns, and silver foutians mud.
# And correct the spelling of `fountains'.
s/utia/untai/p
Roses have thorns, and silver fountains mud.
w sonnet
183
q
$
@end example

@code{ed} may be invoked with or without arguments @xref{Invoking ed}.  When
invoked with a @var{file} argument, a copy of @var{file} is read into
the editor's buffer.  Changes are made to this copy and not directly to
@var{file} itself.  Upon quitting @code{ed}, any changes not explicitly
saved with a @samp{w} command @xref{Commands} are lost.

Since @code{ed} is line-oriented, we have to tell it which line, or
range of lines we want to edit.  In the above example, we do this by
specifying the line's number, or sequence in the buffer.  Alternatively,
we could have specified a unique string in the line, e.g.,
@samp{/filvers/}, where the @samp{/}s delimit the string in question.
Subsequent commands affect only the selected line, a.k.a. the
@dfn{current} line.  Portions of that line are then replaced with the
substitute command, whose syntax is
@samp{s/@var{old}/@var{new}/}.

Although @code{ed} accepts only one command per line,
the print command @samp{p} is an exception, and may be appended to the
end of most commands.

In the next example, a title is added to our sonnet.

@example
$ ed sonnet
183
a
 Sonnet #50
.
,p
No more be grieved at that which thou hast done.
Roses have thorns, and silver fountains mud.
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
 Sonnet #50
# The title got appended to the end; we should have used `0a'
# to append ``before the first line.''
# Move the title to its proper place.
5m0p
 Sonnet #50
# The title is now the first line, and the current line has been
# set to this line as well.
,p
 Sonnet #50
No more be grieved at that which thou hast done.
Roses have thorns, and silver fountains mud.
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
wq sonnet
195
$
@end example

When @code{ed} opens a file, the current line is initially set to the last
line of that file.   Similarly, the move command @samp{m} sets the current
line to the last line moved.

In summary: All @code{ed} commands operate on whole lines or ranges of
lines; e.g., the @samp{d} command deletes lines; the @samp{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 second example above.  However even
there, the @samp{s} command is applied to whole lines at a time.

Structurally, @code{ed} commands consist of zero or more line addresses,
followed by a single character command and possibly additional
parameters; i.e., commands have the structure:

@example
[@var{address} [,@var{address}]]@var{command}[@var{parameters}]
@end example

The @var{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 supplied.

Related programs or routines are @code{vi (1)}, @code{sed (1)},
@code{regex (3)},  @code{sh (1)}.  Relevant documents
are:

@quotation
Unix User's Manual Supplementary Documents: 12 --- 13
@end quotation

@quotation
B. W. Kernighan and P. J. Plauger: ``Software Tools in Pascal'',
Addison-Wesley, 1981.
@end quotation

@node Invoking ed, Line addressing, Intro, Top
@chapter Invoking GNU @code{ed}

@example
ed [-] [-Gs] [-p @var{string}] [@var{file}]
red [-] [-Gs] [-p @var{string}] [@var{file}]
@end example

@table @code

@item -G
Forces backwards compatibility.  This affects the behavior of the @code{ed}
commands @samp{G}, @samp{V}, @samp{f}, @samp{l}, @samp{m}, @samp{t}
and @samp{!!}.  If the default behavior of these commands does not seem
familiar, then try invoking @code{ed} with this switch.

@item -s
@item -
Suppresses diagnostics. This should be used if @code{ed}'s standard
input is from a script.

@item -p @var{string}
Specifies a command prompt.  This may be toggled on and off with the
@samp{P} command.

@end table

@var{file} specifies the name of a file to read.  If @var{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 @var{file} executed
via @code{sh (1)}.  To read a file whose name begins with a bang, prefix
the name with a backslash (@kbd{\}).  The default filename is set to
@var{file} only if it is not prefixed with a bang.

@node Line addressing, Regular expressions, Invoking ed, Top
@chapter Line addressing

An address represents the number of a line in the buffer.  @code{ed}
maintains a @dfn{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., @samp{+}, @samp{-} and @samp{^})
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 @samp{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 @var{n}-tuple of
addresses is given where @var{n} > 2, then the corresponding range is
determined by the last two addresses in the @var{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.

@table @code

@item .
The current line (address) in the buffer.

@item $
The last line in the buffer.

@item @var{n}
The @var{n}th, line in the buffer where @var{n} is a number in the range
@samp{0,$}.

@item -
@itemx ^
The previous line.  This is equivalent to @samp{-1} and may be repeated
with cumulative effect.

@item -@var{n}
@itemx ^@var{n}
The @var{n}th previous line, where @var{n} is a non-negative number.

@item +
The next line.  This is equivalent to @samp{+1} and may be repeated with
cumulative effect.

@item +@var{n}
@itemx @var{whitespace} @var{n}
The @var{n}th next line, where @var{n} is a non-negative number.
Whitespace followed by a number @var{n} is interpreted as
@samp{+@var{n}}.

@item ,
@itemx %
The first through last lines in the buffer.  This is equivalent to the
address range @samp{1,$}.

@item ;
The current through last lines in the buffer.  This is equivalent to the
address range @samp{.,$}.

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

@item ?@var{re}?
The previous line containing the regular expression @var{re}.  The
search wraps to the end of the buffer and continues up to the current
line, if necessary.  @samp{??} repeats the last search.

@item '@var{lc}
The line previously marked by a @samp{k} (mark) command, where @var{lc}
is a lower case letter.

@end table

@node Regular expressions, Commands, Line addressing, Top
@chapter Regular expressions

Regular expressions are patterns used in selecting text.  For example,
the @code{ed} command

@example
g/@var{string}/
@end example

@noindent
prints all lines containing @var{string}.  Regular expressions are also
used by the @samp{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 corresponding 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:

@table @code

@item @var{c}
Any character @var{c} not listed below, including @samp{@{}, @samp{@}},
@samp{(}, @samp{)}, @samp{<} and @samp{>}, matches itself.

@item \@var{c}
Any backslash-escaped character @var{c}, other than @samp{@{},
`@samp{@}}, @samp{(}, @samp{)}, @samp{<}, @samp{>}, @samp{b}, @samp{B},
@samp{w}, @samp{W}, @samp{+} and @samp{?}, matches itself.

@item .
Matches any single character.

@item [@var{char-class}]
Matches any single character in @var{char-class}.  To include a @samp{]}
in @var{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 @samp{-}, e.g., @samp{a-z} specifies the lower case
characters.  The following literal expressions can also be used in
@var{char-class} to specify sets of characters:

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

If @samp{-} appears as the first or last character of @var{char-class},
then it matches itself.  All other characters in @var{char-class} match
themselves.

Patterns in
@var{char-class}
of the form:
@example
[.@var{col-elm}.]
[=@var{col-elm}=]
@end example

@noindent
where @var{col-elm} is a @dfn{collating element} are interpreted
according to @code{locale (5)} (not currently supported).  See
@code{regex (3)} for an explanation of these constructs.

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

@item ^
If @samp{^} is the first character of a regular expression, then it
anchors the regular expression to the beginning of a line.  Otherwise,
it matches itself.

@item $
If @samp{$} is the last character of a regular expression, it anchors
the regular expression to the end of a line.  Otherwise, it matches
itself.

@item \(@var{re}\)
Defines a (possibly null) subexpression @var{re}.
Subexpressions may be nested.  A
subsequent backreference of the form @samp{\@var{n}}, where @var{n} is a
number in the range [1,9], expands to the text matched by the @var{n}th
subexpression. For example, the regular expression @samp{\(a.c\)\1} matches
the string @samp{abcabc}, but not @samp{abcadc}.
Subexpressions are ordered relative to their left delimiter.

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

@item \@{@var{n,m}\@}
@itemx \@{@var{n,}\@}
@itemx \@{@var{n}\@}
Matches the single character regular expression or subexpression
immediately preceding it at least @var{n} and at most @var{m} times.  If
@var{m} is omitted, then it matches at least @var{n} times.  If the
comma is also omitted, then it matches exactly @var{n} times.
If any of these forms occurs first in a regular expression or subexpression,
then it is interpreted literally (i.e., the regular expression @samp{\@{2\@}}
matches the string @samp{@{2@}}, and so on).

@item \<
@itemx \>
Anchors the single character regular expression or subexpression
immediately following it to the beginning (in the case of @samp{\<})
or ending (in the case of @samp{\>}) of
a @dfn{word}, i.e., in ASCII, a maximal string of alphanumeric characters,
including the underscore (_).

@end table

The following extended operators are preceded by a backslash @samp{\} to
distinguish them from traditional @code{ed} syntax.

@table @code

@item  \`
@itemx \'
Unconditionally matches the beginning @samp{\`} or ending @samp{\'} of a line.

@item \?
Optionally matches the single character regular expression or subexpression
immediately preceding it.  For example, the regular expression @samp{a[bd]\?c}
matches the strings @samp{abc}, @samp{adc} and @samp{ac}.
If @samp{\?} occurs at the beginning
of a regular expressions or subexpression, then it matches a literal @samp{?}.

@item \+
Matches the single character regular expression or subexpression
immediately preceding it one or more times.  So the regular expression
@samp{a+} is shorthand for @samp{aa*}.  If @samp{\+} occurs at the
beginning of a regular expression or subexpression, then it matches a
literal @samp{+}.

@item \b
Matches the beginning or ending (null string) of a word.  Thus the regular
expression @samp{\bhello\b} is equivalent to @samp{\<hello\>}.
However, @samp{\b\b}
is a valid regular expression whereas @samp{\<\>} is not.

@item \B
Matches (a null string) inside a word.

@item \w
Matches any character in a word.

@item \W
Matches any character not in a word.

@end table

@node Commands, Limitations, Regular expressions, Top
@chapter Commands

All @code{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 (@samp{\}).

In general, at most one command is allowed per line.  However, most
commands accept a print suffix, which is any of @samp{p} (print),
@samp{l} (list), or @samp{n} (enumerate), to print the last line
affected by the command.

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

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

@table @code

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

@item (.,.)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.

@item (.,.)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.

@item e @var{file}
Edits @var{file}, and sets the default filename.  If @var{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.

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

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

@item f @var{file}
Sets the default filename to @var{file}.  If @var{file} is not
specified, then the default unescaped filename is printed.

@item (1,$)g /@var{re}/@var{command-list}
Applies @var{command-list} to each of the addressed lines matching a
regular expression @var{re}.  The current address is set to the line
currently matched before @var{command-list} is executed.  At the end of
the @samp{g} command, the current address is set to the last line
affected by @var{command-list}.

Each command in @var{command-list} must be on a separate line, and every
line except for the last must be terminated by a backslash (@samp{\}).
Any commands are allowed, except for @samp{g}, @samp{G}, @samp{v}, and
@samp{V}.  By default, a newline alone in @var{command-list} is
equivalent to a @samp{p} command.  If @code{ed} is invoked with the
command-line option @samp{-G}, then a newline in @var{command-list}
is equivalent to a @samp{.+1p} command.

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

The format of @var{command-list} is the same as that of the @samp{g}
command.  A newline alone acts as a null command list.  A single
@samp{&} repeats the last non-null command list.

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

@item h
Prints an explanation of the last error.

@item (.)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.

@item (.,.+1)j
Joins the addressed lines.  The addressed lines are deleted from the
buffer and replaced by a single line containing their joined text.  The
current address is set to the resultant line.

@item (.)k @var{lc}
Marks a line with a lower case letter @var{lc}.  The line can then be
addressed as @samp{'@var{lc}} (i.e., a single quote followed by
@var{lc}) in subsequent commands.  The mark is not cleared until the
line is deleted or otherwise modified.

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

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

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

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

@item P
Toggles the command prompt on and off.  Unless a prompt is specified
with command-line option @samp{-p @var{string}}, the command prompt is
by default turned off.

@item q
Quits @code{ed}.

@item Q
Quits @code{ed} unconditionally.  This is similar to the @code{q}
command, except that unwritten changes are discarded without warning.

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

@item ($)r !@var{command}
Reads to after the addressed line the standard output of
@samp{!command}, (see the @samp{!} command below).  The default filename
is unchanged.  The current address is set to the last line read.

@item (.,.)s /@var{re}/@var{replacement}/
@itemx (.,.)s /@var{re}/@var{replacement}/g
@itemx (.,.)s /@var{re}/@var{replacement}/n
Replaces text in the addressed lines matching a regular expression
@var{re} with @var{replacement}.  By default, only the first match in
each line is replaced.  If the @samp{g} (global) suffix is given, then
every match to be replaced.  The @samp{n} suffix, where @var{n} is a
postive number, causes only the @var{n}th match to be replaced.  It is
an error if no substitutions are performed on any of the addressed
lines.  The current address is set the last line affected.

@var{re} and @var{replacement} may be delimited by any character other
than @key{space} and @key{newline} (see the @samp{s} command below).  If
one or two of the last delimiters is omitted, then the last line
affected is printed as though the print suffix @samp{p} were specified.

An unescaped @samp{&} in @var{replacement} is replaced by the currently
matched text.  The character sequence @samp{\@var{m}} where @var{m} is a
number in the range [1,9], is replaced by the @var{m}th backreference
expression of the matched text.  If @var{replacement} consists of a
single @samp{%}, then @var{replacement} from the last substitution is
used.  Newlines may be embedded in @var{replacement} if they are escaped
with a backslash (@samp{\}).

@item (.,.)s
Repeats the last substitution.  This form of the @samp{s} command
accepts a count suffix @var{n}, or any combination of the characters
@samp{r}, @samp{g}, and @samp{p}.  If a count suffix @var{n} is given,
then only the @var{n}th match is replaced.  The @samp{r} suffix causes
the regular expression of the last search to be used instead of the that
of the last substitution.  The @samp{g} suffix toggles the global suffix
of the last substitution.  The @samp{p} suffix toggles the print suffix
of the last substitution The current address is set to the last line
affected.

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

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

@item (1,$)v /@var{re}/@var{command-list}
Applies @var{command-list} to each of the addressed lines not matching a
regular expression @var{re}.  This is similar to the @samp{g} command.

@item (1,$)V /@var{re}/
Interactively edits the addressed lines not matching a regular
expression @var{re}.  This is similar to the @samp{G} command.

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

@item (1,$)wq @var{file}
Writes the addressed lines to @var{file}, and then executes a @samp{q}
command.

@item (1,$)w !@var{command}
Writes the addressed lines to the standard input of
@samp{!@var{command}}, (see the @samp{!} command below).  The default
filename and current address are unchanged.

@item (1,$)W @var{file}
Appends the addressed lines to the end of @var{file}.  This is similar
to the @samp{w} command, expect that the previous contents of file is
not clobbered.  The current address is unchanged.


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

@item (.,.)y
Copies (yanks) the addressed lines to the cut buffer.
The cut buffer is overwritten by subsequent
@samp{y}, @samp{s}, @samp{j}, @samp{d}, or @samp{c} commands.
The current address is unchanged.

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

@item ! @var{command}
Executes @var{command} via @code{sh (1)}.  If the first character of
@var{command} is @samp{!}, then it is replaced by text of the previous
@samp{!@var{command}}.  @code{ed} does not process @var{command} for
backslash (@samp{\}) escapes.  However, an unescaped @samp{%} is
replaced by the default filename.  When the shell returns from
execution, a @samp{!} is printed to the standard output.  The current
line is unchanged.

@item (.,.)#
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.

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

@item (.+1)@key{newline}
Prints the addressed line, and sets the current address to that line.

@end table

@node Limitations, Diagnostics, Commands, Top
@chapter Limitations

The buffer files are kept in @file{/tmp/ed.*}.  If the terminal hangs
up, @code{ed} attempts to write the buffer to file @file{ed.hup}.

@code{ed} processes @var{file} arguments for backslash escapes, i.e., in
a filename, any characters preceded by a backslash (@samp{\}) are
interpreted literally.

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

Per line overhead: 4 @code{int}s.

@node Diagnostics,  , Limitations, Top
@chapter Diagnostics

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

@noindent
If the @samp{u}
(undo) command occurs in a global command list, then the command list is
executed only once.

Attempting to quit @code{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.

@code{ed} exits with 0 if no errors occurred; otherwise >0.

@contents
@bye