bin/ed/ed.1

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.\"
.\" Copyright (c) 1993 Andrew Moore, Talke Studio.
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.Dd $Mdocdate: April 14 2014 $
.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
.Dl [address [,address]]command[parameters]
.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,$] .
.It - or ^
The previous line.
This is equivalent to
.Ad \-1
and may be repeated with cumulative effect.
.It Xo
.Pf - Ns Ar n No or\ \&
.Pf ^ Ns Ar n
.Xc
The
.Ar n Ns th
previous line, where
.Ar n
is a non-negative number.
.It +
The next line.
This is equivalent to
.Ad +1
and may be repeated with cumulative effect.
.It + Ns Ar n
The
.Ar n Ns th
next line, where
.Ar n
is a non-negative number.
.It \&, or %
The first through last lines in the buffer.
This is equivalent to the address range
.Ad 1,$ .
.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.
.Qq //
repeats the last search.
.It ? Ns Ar re Ns ?
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.
.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,$) Ic g No /
.Ar re No / Ar command-list
.Xc
.Sm on
Applies
.Ar command-list
to each of the addressed lines matching a regular expression
.Ar re .
The current address is set to the line currently matched before
command-list is executed.
At the end of the
.Ic g
command, the current address is set to the last line affected by command-list.
If no lines were matched,
the current line number remains unchanged.
.Pp
Each command in
.Ar command-list
must be on a separate line,
and every line except for the last must be terminated by a backslash
.Pq Sq \e .
Any commands are allowed, except for
.Ic g ,
.Ic G ,
.Ic v ,
and
.Ic V .
A newline alone in command-list is equivalent to a
.Ic p
command.
.Sm off
.It (1,$) Ic G No / Ar re No /
.Sm on
Interactively edits the addressed lines matching a regular expression
.Ar re .
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.
A newline alone acts as a null command list.
A single
.Sq &
repeats the last non-null 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 (.,.+1) 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.
If a single line fills more than one screen (as might be the case
when viewing a binary file, for instance), a
.Dq --More--
prompt is printed on the last line.
.Nm
waits until the RETURN key is pressed before displaying the next screen.
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 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 Ns 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,$) Ic v No / Ar re
.Pf / Ar command-list
.Xc
.Sm on
Applies
.Ar command-list
to each of the addressed lines not matching a regular expression
.Ar re .
This is similar to the
.Ic g
command.
.Sm off
.It Xo
.Pf (1,$) Ic V No /
.Ar re No /
.Xc
.Sm on
Interactively edits the addressed lines not matching a regular expression
.Ar re .
This is similar to the
.Ic G
command.
.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 (.+1) 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 (.+1) Ns newline
Prints the addressed line, and sets the current address to that 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
.%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 W
and
.Cm z
and 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.