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ED(1P) POSIX Programmer's Manual ED(1P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
NAME
ed -- edit text
SYNOPSIS
ed [-p string] [-s] [file]
DESCRIPTION
The ed utility is a line-oriented text editor that uses two
modes: command mode and input mode. In command mode the input
characters shall be interpreted as commands, and in input mode
they shall be interpreted as text. See the EXTENDED DESCRIPTION
section.
If an operand is '-', the results are unspecified.
OPTIONS
The ed utility shall conform to the Base Definitions volume of
POSIX.1-2017, Section 12.2, Utility Syntax Guidelines, except for
the unspecified usage of '-'.
The following options shall be supported:
-p string Use string as the prompt string when in command mode.
By default, there shall be no prompt string.
-s Suppress the writing of byte counts by e, E, r, and w
commands and of the '!' prompt after a !command.
OPERANDS
The following operand shall be supported:
file If the file argument is given, ed shall simulate an e
command on the file named by the pathname, file, before
accepting commands from the standard input.
STDIN
The standard input shall be a text file consisting of commands,
as described in the EXTENDED DESCRIPTION section.
INPUT FILES
The input files shall be text files.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of
ed:
HOME Determine the pathname of the user's home directory.
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1-2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the locale for the behavior of ranges,
equivalence classes, and multi-character collating
elements within regular expressions.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files) and the
behavior of character classes within regular
expressions.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error and informative messages written to
standard output.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
ASYNCHRONOUS EVENTS
The ed utility shall take the standard action for all signals
(see the ASYNCHRONOUS EVENTS section in Section 1.4, Utility
Description Defaults) with the following exceptions:
SIGINT The ed utility shall interrupt its current activity,
write the string "?\n" to standard output, and return
to command mode (see the EXTENDED DESCRIPTION section).
SIGHUP If the buffer is not empty and has changed since the
last write, the ed utility shall attempt to write a
copy of the buffer in a file. First, the file named
ed.hup in the current directory shall be used; if that
fails, the file named ed.hup in the directory named by
the HOME environment variable shall be used. In any
case, the ed utility shall exit without writing the
file to the currently remembered pathname and without
returning to command mode.
SIGQUIT The ed utility shall ignore this event.
STDOUT
Various editing commands and the prompting feature (see -p) write
to standard output, as described in the EXTENDED DESCRIPTION
section.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
The output files shall be text files whose formats are dependent
on the editing commands given.
EXTENDED DESCRIPTION
The ed utility shall operate on a copy of the file it is editing;
changes made to the copy shall have no effect on the file until a
w (write) command is given. The copy of the text is called the
buffer.
Commands to ed have a simple and regular structure: zero, one, or
two addresses followed by a single-character command, possibly
followed by parameters to that command. These addresses specify
one or more lines in the buffer. Every command that requires
addresses has default addresses, so that the addresses very often
can be omitted. If the -p option is specified, the prompt string
shall be written to standard output before each command is read.
In general, only one command can appear on a line. Certain
commands allow text to be input. This text is placed in the
appropriate place in the buffer. While ed is accepting text, it
is said to be in input mode. In this mode, no commands shall be
recognized; all input is merely collected. Input mode is
terminated by entering a line consisting of two characters: a
<period> ('.') followed by a <newline>. This line is not
considered part of the input text.
Regular Expressions in ed
The ed utility shall support basic regular expressions, as
described in the Base Definitions volume of POSIX.1-2017, Section
9.3, Basic Regular Expressions. Since regular expressions in ed
are always matched against single lines (excluding the
terminating <newline> characters), never against any larger
section of text, there is no way for a regular expression to
match a <newline>.
A null RE shall be equivalent to the last RE encountered.
Regular expressions are used in addresses to specify lines, and
in some commands (for example, the s substitute command) to
specify portions of a line to be substituted.
Addresses in ed
Addressing in ed relates to the current line. Generally, the
current line is the last line affected by a command. The current
line number is the address of the current line. If the edit
buffer is not empty, the initial value for the current line shall
be the last line in the edit buffer; otherwise, zero.
Addresses shall be constructed as follows:
1. The <period> character ('.') shall address the current line.
2. The <dollar-sign> character ('