.\" $OpenBSD: ed.1,v 1.77 2022/06/19 05:49:51 jmc Exp $

.\"

.\" Copyright (c) 1993 Andrew Moore, Talke Studio.

.\" All rights reserved.

.\"

.\" Redistribution and use in source and binary forms, with or without

.\" modification, are permitted provided that the following conditions

.\" are met:

.\" 1. Redistributions of source code must retain the above copyright

.\" notice, this list of conditions and the following disclaimer.

.\" 2. Redistributions in binary form must reproduce the above copyright

.\" notice, this list of conditions and the following disclaimer in the

.\" documentation and/or other materials provided with the distribution.

.\"

.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND

.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

.\" SUCH DAMAGE.

.\"

.Dd $Mdocdate: June 19 2022 $

.Dt ED 1

.Os

.Sh NAME

.Nm ed

.Nd text editor

.Sh SYNOPSIS

.Nm ed

.Op Fl

.Op Fl s

.Op Fl p Ar string

.Op Ar file

.Sh DESCRIPTION

.Nm

is a line-oriented text editor.

It is used to create, display, modify, and otherwise manipulate text files.

If invoked with a

.Ar file

argument, then a copy of

.Ar file

is read into the editor's buffer.

Changes are made to this copy and not directly to

.Ar file

itself.

Upon quitting

.Nm ed ,

any changes not explicitly saved with a

.Ic w

command are lost.

.Pp

Editing is done in two distinct modes:

.Em command

and

.Em input .

When first invoked,

.Nm

is in command mode.

In this mode, commands are read from the standard input and

executed to manipulate the contents of the editor buffer.

.Pp

A typical command might look like:

.Pp

.Dl ,s/old/new/g

.Pp

which replaces all occurrences of the string

.Qq old

with

.Qq new .

.Pp

When an input command, such as

.Ic a

.Pq append ,

.Ic i

.Pq insert ,

or

.Ic c

.Pq change

is given,

.Nm

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

.Pq Ql \&.

on a line.

.Pp

All

.Nm

commands operate on whole lines or ranges of lines; e.g.,

the

.Ic d

command deletes lines; the

.Ic 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

.Ic s

command is applied to whole lines at a time.

.Pp

In general,

.Nm

commands consist of zero or more line addresses, followed by a single

character command and possibly additional parameters; i.e.,

commands have the structure:

.Pp

.Sm off

.D1 Oo Ar address Oo , Ar address Oc Oc Ar command Op Ar parameters

.Sm on

.Pp

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 supplied.

.Pp

Many

.Nm

commands and line addresses support basic regular expressions

.Pq BREs .

See

.Xr re_format 7

for more information on regular expressions.

.Pp

The options are as follows:

.Bl -tag -width "-p string"

.It Fl

Same as the

.Fl s

option

.Pq deprecated .

.It Fl p Ar string

Specifies a command prompt.

This may be toggled on and off with the

.Ic P

command.

.It Fl s

Suppress diagnostics.

This should be used if

.Nm

standard input is from a script.

.It Ar file

Specifies the name of a file to read.

If

.Ar file

is prefixed with a

bang

.Pq Ql \&! ,

then it is interpreted as a shell command.

In this case, what is read is the standard output of

.Ar file

executed via

.Xr sh 1 .

To read a file whose name begins with a bang, prefix the

name with a backslash

.Pq Ql \e .

The default filename is set to

.Ar file

only if it is not prefixed with a bang.

.El

.Ss LINE ADDRESSING

An address represents the number of a line in the buffer.

.Nm

maintains a

.Em 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.

.Pp

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 (e.g.,

.Ql + ,

.Ql - ,

and

.Ql ^ ) ,

and whitespace.

Addresses are read from left to right, and their values are computed

relative to the current address.

.Pp

One exception to the rule that addresses represent line numbers is the

address

.Ad 0

.Pq zero .

This means

.Dq before the first line ,

and is legal wherever it makes sense.

.Pp

An address range is two addresses separated either by a comma or semi-colon.

The value of the first address in a range cannot exceed the

value of the second.

If only one address is given in a range,

then the second address is set to the given address.

If an

.Ar n Ns -tuple

of addresses is given where

.Ar n

\*(Gt 2,

then the corresponding range is determined by the last two addresses in the

.Ar n Ns -tuple .

If only one address is expected, then the last address is used.

.Pp

Each address in a comma-delimited range is interpreted relative to the

current address.

In a semi-colon-delimited range, the first address is

used to set the current address, and the second address is interpreted

relative to the first.

.Pp

The following address symbols are recognized:

.Bl -tag -width Ds

.It \&.

The current line

.Pq address

in the buffer.

.It $

The last line in the buffer.

.It Ar n

The

.Ar n Ns th

line in the buffer, where

.Ar n

is a number in the range

.Ad [0,$] .

.It - or ^

The previous line.

This is equivalent to

.Ad \-1

and may be repeated with cumulative effect.

.It Xo

.Pf - Ar n No or\ \&

.Pf ^ Ar n

.Xc

The

.Ar n Ns th

previous line, where

.Ar n

is a non-negative number.

.It +

The next line.

This is equivalent to

.Ad +1

and may be repeated with cumulative effect.

.It + Ns Ar n

The

.Ar n Ns th

next line, where

.Ar n

is a non-negative number.

.It \&, or %

The first through last lines in the buffer.

This is equivalent to the address range

.Ad 1,$ .

.It \&;

The current through last lines in the buffer.

This is equivalent to the address range

.Ad .,$ .

.It / Ns Ar re Ns /

The next line containing the regular expression

.Ar re .

The search wraps to the beginning of the buffer and continues down to the

current line, if necessary.

The second slash can be omitted if it ends a line.

.Qq //

repeats the last search.

.It Pf ? Ar re ?

The previous line containing the regular expression

.Ar re .

The search wraps to the end of the buffer and continues up to the

current line, if necessary.

The second question mark can be omitted if it ends a line.

.Qq ??

repeats the last search.

.It \&' Ns Ar lc

The line previously marked by a

.Ic k

.Pq mark

command, where

.Ar lc

is a lower case letter.

.El

.Ss COMMANDS

All

.Nm

commands are single characters, though some require additional parameters.

If a command's parameters extend over several lines, then

each line except for the last must be terminated with a backslash

.Pq Ql \e .

.Pp

In general, at most one command is allowed per line.

However, most commands accept a print suffix, which is any of

.Ic p

.Pq print ,

.Ic l

.Pq list ,

or

.Ic n

.Pq enumerate ,

to print the last line affected by the command.

.Pp

.Nm

recognizes the following commands.

The commands are shown together with

the default address or address range supplied if none is specified

.Pq in parentheses ,

and other possible arguments on the right.

.Bl -tag -width Dxxs

.It (.) Ns Ic a

Appends text to the buffer after the addressed line.

Text is entered in input mode.

The current address is set to last line entered.

.It (.,.) Ns Ic 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.

.It (.,.) Ns Ic 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.

.It Ic e Ar file

Edits

.Ar file ,

and sets the default filename.

If

.Ar 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.

.It Ic e No \&! Ns Ar command

Edits the standard output of

.No \&! Ns Ar command ,

(see

.Ic \&! Ns Ar command

below).

The default filename is unchanged.

Any lines in the buffer are deleted before the output of

.Ar command

is read.

The current address is set to the last line read.

.It Ic E Ar file

Edits

.Ar file

unconditionally.

This is similar to the

.Ic e

command, except that unwritten changes are discarded without warning.

The current address is set to the last line read.

.It Ic f Ar file

Sets the default filename to

.Ar file .

If

.Ar file

is not specified, then the default unescaped filename is printed.

.Sm off

.It Xo

.Pf (1,$) Ic g No /

.Ar re No / Ar command-list

.Xc

.Sm on

Mark each addressed line matching the regular expression

.Ar re

for modification.

The current address is set to each marked line in turn, and then the

.Ar command-list

is executed each time.

The command-list can change the current line number,

and it is not changed back after the command-list ended.

When a marked line is changed, it is unmarked

and the command-list won't be executed for it any more.

If no lines were matched,

the current line number remains unchanged.

.Pp

Each command in

.Ar command-list

must be on a separate line,

and every line except for the last must be terminated by a backslash

.Pq Sq \e .

Any commands are allowed, except for

.Ic g ,

.Ic G ,

.Ic v ,

and

.Ic V .

An empty

.Ar command-list

is equivalent to a

.Ic p

command \(em unlike for the

.Cm G

command, where an empty command-list does nothing, and unlike an empty

command, which is equivalent to the command

.Cm +p .

If the

.Ar command-list

is empty, the trailing slash can be omitted.

.Sm off

.It (1,$) Ic G No / Ar re No /

.Sm on

Interactively edits the addressed lines matching a regular expression

.Ar re .

The trailing slash after

.Ar re

can be omitted.

For each matching line, the line is printed, the current address is set,

and the user is prompted to enter a

.Ar command-list .

At the end of the

.Ic G

command, the current address is set to the last line affected by

.Pq the last

command-list.

If no lines were matched,

the current line number remains unchanged.

.Pp

The format of

.Ar command-list

is the same as that of the

.Ic g

command, but an empty command list does nothing.

A single

.Sq &

repeats the last non-empty command list.

.It Ic H

Toggles the printing of error explanations.

By default, explanations are not printed.

It is recommended that

.Nm

scripts begin with this command to aid in debugging.

.It Ic h

Prints an explanation of the last error.

.It (.) Ns Ic 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.

.It (.,+) Ns Ic 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.

.It (.) Ns Ic k Ns Ar lc

Marks a line with a lower case letter

.Ar lc .

The line can then be addressed as

.Ic ' Ns Ar lc

(i.e., a single quote followed by

.Ar lc )

in subsequent commands.

The mark is not cleared until the line is deleted or otherwise modified.

.It (.,.) Ns Ic l

Prints the addressed lines unambiguously.

The current address is set to the last line printed.

.It (.,.) Ns Ic m Ns (.)

Moves lines in the buffer.

The addressed lines are moved to after the

right-hand destination address, which may be the address

.Ad 0

.Pq zero .

The current address is set to the last line moved.

.It (.,.) Ns Ic n

Prints the addressed lines along with their line numbers.

The current address is set to the last line printed.

.It (.,.) Ns Ic p

Prints the addressed lines.

The current address is set to the last line printed.

.It Ic P

Toggles the command prompt on and off.

Unless a prompt was specified with the command-line option

.Fl p Ar string ,

the command prompt is by default turned off.

.It Ic q

Quits

.Nm ed .

.It Ic Q

Quits

.Nm

unconditionally.

This is similar to the

.Ic q

command, except that unwritten changes are discarded without warning.

.It ($) Ns Ic r Ar file

Reads

.Ar file

to after the addressed line.

If

.Ar 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

.Ar file .

Otherwise, the default filename is unchanged.

The current address is set to the last line read.

.It ($) Ns Ic r No \&! Ns Ar command

Reads to after the addressed line the standard output of

.No \&! Ns Ar command ,

(see

.Ic \&! Ns Ar command

below).

The default filename is unchanged.

The current address is set to the last line read.

.Sm off

.It Xo

.Pf (.,.) Ic s No / Ar re

.No / Ar replacement No /\ \&

.Pf (.,.) Ic s No / Ar re

.No / Ar replacement No / Ic g\ \&

.No (.,.) Ic s No / Ar re

.No / Ar replacement No / Ar n

.Xc

.Sm on

Replaces text in the addressed lines matching a regular expression

.Ar re

with

.Ar replacement .

By default, only the first match in each line is replaced.

If the

.Ic g

.Pq global

suffix is given, then every match is replaced.

The

.Ar n

suffix, where

.Ar n

is a positive number, causes only the

.Ar n Ns 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 to the last line affected.

.Pp

.Ar re

and

.Ar replacement

may be delimited by any character other than space and newline

(see the

.Ic 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

.Ic p

were specified.

.Pp

An unescaped

.Ql &

in

.Ar replacement

is replaced by the currently matched text.

The character sequence

.Pf \e Ar m ,

where

.Ar m

is a number in the range [1,9], is replaced by the

.Ar m Ns th

backreference expression of the matched text.

If

.Ar replacement

consists of a single

.Ql % ,

then

.Ar replacement

from the last substitution is used.

Newlines may be embedded in

.Ar replacement

if they are escaped with a backslash

.Pq Ql \e .

.It (.,.) Ns Ic s

Repeats the last substitution.

This form of the

.Ic s

command accepts a count suffix

.Ar n ,

or any combination of the characters

.Ic r ,

.Ic g ,

and

.Ic p .

If a count suffix

.Ar n

is given, then only the

.Ar n Ns th

match is replaced.

The

.Ic r

suffix causes the regular expression of the last search to be used

instead of that of the last substitution.

The

.Ic g

suffix toggles the global suffix of the last substitution.

The

.Ic p

suffix toggles the print suffix of the last substitution.

The current address is set to the last line affected.

.It (.,.) Ns Ic t Ns (.)

Copies

.Pq i.e., transfers

the addressed lines to after the right-hand destination address,

which may be the address

.Ad 0

.Pq zero .

The current address is set to the last line copied.

.It Ic u

Undoes the last command and restores the current address

to what it was before the command.

The global commands

.Ic g ,

.Ic G ,

.Ic v ,

and

.Ic V

are treated as a single command by undo.

.Ic u

is its own inverse.

.Sm off

.It Xo

.Pf (1,$) Ic v No / Ar re

.Pf / Ar command-list

.Xc

.Sm on

The same as the

.Ic g

command, except that it applies

.Ar command-list

to each of the addressed lines not matching the regular expression

.Ar re .

.Sm off

.It Xo

.Pf (1,$) Ic V No /

.Ar re No /

.Xc

.Sm on

The same as the

.Ic G

command, except that it interactively edits the addressed lines

not matching the regular expression

.Ar re .

.It (1,$) Ns Ic w Ar file

Writes the addressed lines to

.Ar file .

Any previous contents of

.Ar file

are lost without warning.

If there is no default filename, then the default filename is set to

.Ar file ,

otherwise it is unchanged.

If no filename is specified, then the default filename is used.

The current address is unchanged.

.It (1,$) Ns Ic wq Ar file

Writes the addressed lines to

.Ar file ,

and then executes a

.Ic q

command.

.It (1,$) Ns Ic w No \&! Ns Ar command

Writes the addressed lines to the standard input of

.No \&! Ns Ar command ,

(see

.Ic \&! Ns Ar command

below).

The default filename and current address are unchanged.

.It (1,$) Ns Ic W Ar file

Appends the addressed lines to the end of

.Ar file .

This is similar to the

.Ic w

command, except that the previous contents of file are not clobbered.

The current address is unchanged.

.It (+) Ns Ic z Ns Ar n

Scrolls

.Ar n

lines at a time starting at addressed line.

If

.Ar n

is not specified, then the current window size is used.

The current address is set to the last line printed.

.It ($) Ns Ic =

Prints the line number of the addressed line.

.It (+)

An address without a command prints the addressed line

and sets the current address to that line.

If the address is also omitted, it defaults to the next line (+).

.It Ic \&! Ns Ar command

Executes

.Ar command

via

.Xr sh 1 .

If the first character of

.Ar command

is

.Sq !\& ,

then it is replaced by text of the previous

.Ic \&! Ns Ar command .

.Nm

does not process

.Ar command

for

.Sq \e

.Pq backslash

escapes.

However, an unescaped

.Sq %

is replaced by the default filename.

When the shell returns from execution, a

.Sq \&!

is printed to the standard output.

The current line is unchanged.

.El

.Sh ASYNCHRONOUS EVENTS

.Bl -tag -width "SIGWINCH"

.It Dv SIGHUP

If the current buffer has changed since it was last written,

.Nm

attempts to write the buffer to the file

.Pa ed.hup .

Nothing is written to the currently remembered file, and

.Nm

exits.

.It Dv SIGINT

When an interrupt occurs,

.Nm

prints

.Sq ?\en

and returns to command mode.

If interrupted during text input,

the text already input is written to the current buffer,

as if text input had been normally terminated.

.It Dv SIGQUIT

This signal is ignored.

.It Dv SIGWINCH

The screen is resized.

.El

.Sh FILES

.Bl -tag -width /tmp/ed.* -compact

.It Pa /tmp/ed.*

buffer file

.It Pa ed.hup

where

.Nm

attempts to write the buffer if the terminal hangs up

.El

.Sh EXIT STATUS

.Ex -std ed

.Sh DIAGNOSTICS

When an error occurs,

.Nm

prints a

.Sq \&?

and either returns to command mode or exits if its input is from a script.

An explanation of the last error can be printed with the

.Ic h

.Pq help

command.

.Pp

Since the

.Ic g

.Pq global

command masks any errors from failed searches and substitutions,

it can be used to perform conditional operations in scripts; e.g.,

.Pp

.Dl g/old/s//new/

.Pp

replaces any occurrences of

.Qq old

with

.Qq new .

.Pp

If the

.Ic u

.Pq undo

command occurs in a global command list,

then the command list is executed only once.

.Pp

If diagnostics are not disabled, attempting to quit

.Nm

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.

.Sh SEE ALSO

.Xr sed 1 ,

.Xr sh 1 ,

.Xr vi 1 ,

.Xr re_format 7

.Rs

.\" 4.4BSD USD:9

.%A B. W. Kernighan

.%T A Tutorial Introduction to the UNIX Text Editor

.Re

.Rs

.\" 4.4BSD USD:10

.%A B. W. Kernighan

.%T Advanced Editing on UNIX

.Re

.Rs

.%A B. W. Kernighan

.%A P. J. Plauger

.%B Software Tools in Pascal

.%O Addison-Wesley

.%D 1981

.Re

.Sh STANDARDS

The

.Nm

utility is compliant with the

.St -p1003.1-2008

specification.

.Pp

The commands

.Cm s

(to repeat the last substitution),

.Cm W ,

.Cm wq ,

and

.Cm z

as well as the address specifier

.Sq %

are extensions to that specification.

.Pp

The

.St -p1003.1-2008

specification says the

.Sq ^

address specifier is neither required nor prohibited;

additionally, it says behaviour for the

.Fl

option is

.Dq unspecified .

.Sh HISTORY

An

.Nm

command appeared in

.At v1 .

.Sh CAVEATS

.Nm

processes

.Ar file

arguments for backslash escapes, i.e., in a filename,

any characters preceded by a backslash

.Pq Ql \e

are interpreted literally.

.Pp

If a text

.Pq non-binary

file is not terminated by a newline character,

then

.Nm

appends one on reading/writing it.

In the case of a binary file,

.Nm

does not append a newline on reading/writing.