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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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ED(1P) POSIX Programmer's Manual ED(1P)
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.
ed — edit text
ed [−p string] [−s] [file]
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.
The ed utility shall conform to the Base Definitions volume of
POSIX.1‐2008, 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.
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.
The standard input shall be a text file consisting of commands, as
described in the EXTENDED DESCRIPTION section.
The input files shall be text files.
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.1‐2008, 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.
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.
Various editing commands and the prompting feature (see −p) write to
standard output, as described in the EXTENDED DESCRIPTION section.
The standard error shall be used only for diagnostic messages.
The output files shall be text files whose formats are dependent on
the editing commands given.
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.1‐2008, 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 ('$') shall address the last line of
the edit buffer.
3. The positive decimal number n shall address the nth line of the
edit buffer.
4. The <apostrophe>-x character pair ("'x") shall address the line
marked with the mark name character x, which shall be a lowercase
letter from the portable character set. It shall be an error if
the character has not been set to mark a line or if the line that
was marked is not currently present in the edit buffer.
5. A BRE enclosed by <slash> characters ('/') shall address the
first line found by searching forwards from the line following
the current line toward the end of the edit buffer and stopping
at the first line for which the line excluding the terminating
<newline> matches the BRE. The BRE consisting of a null BRE
delimited by a pair of <slash> characters shall address the next
line for which the line excluding the terminating <newline>
matches the last BRE encountered. In addition, the second <slash>
can be omitted at the end of a command line. Within the BRE, a
<backslash>-<slash> pair ("\/") shall represent a literal <slash>
instead of the BRE delimiter. If necessary, the search shall wrap
around to the beginning of the buffer and continue up to and
including the current line, so that the entire buffer is
searched.
6. A BRE enclosed by <question-mark> characters ('?') shall address
the first line found by searching backwards from the line
preceding the current line toward the beginning of the edit
buffer and stopping at the first line for which the line
excluding the terminating <newline> matches the BRE. The BRE
consisting of a null BRE delimited by a pair of <question-mark>
characters ("??") shall address the previous line for which the
line excluding the terminating <newline> matches the last BRE
encountered. In addition, the second <question-mark> can be
omitted at the end of a command line. Within the BRE, a
<backslash>-<question-mark> pair ("\?") shall represent a literal
<question-mark> instead of the BRE delimiter. If necessary, the
search shall wrap around to the end of the buffer and continue up
to and including the current line, so that the entire buffer is
searched.
7. A <plus-sign> ('+') or <hyphen> character ('−') followed by a
decimal number shall address the current line plus or minus the
number. A <plus-sign> or <hyphen> character not followed by a
decimal number shall address the current line plus or minus 1.
Addresses can be followed by zero or more address offsets, optionally
<blank>-separated. Address offsets are constructed as follows:
* A <plus-sign> or <hyphen> character followed by a decimal number
shall add or subtract, respectively, the indicated number of
lines to or from the address. A <plus-sign> or <hyphen> character
not followed by a decimal number shall add or subtract 1 to or
from the address.
* A decimal number shall add the indicated number of lines to the
address.
It shall not be an error for an intermediate address value to be less
than zero or greater than the last line in the edit buffer. It shall
be an error for the final address value to be less than zero or
greater than the last line in the edit buffer. It shall be an error
if a search for a BRE fails to find a matching line.
Commands accept zero, one, or two addresses. If more than the
required number of addresses are provided to a command that requires
zero addresses, it shall be an error. Otherwise, if more than the
required number of addresses are provided to a command, the addresses
specified first shall be evaluated and then discarded until the
maximum number of valid addresses remain, for the specified command.
Addresses shall be separated from each other by a <comma> (',') or
<semicolon> character (';'). In the case of a <semicolon> separator,
the current line ('.') shall be set to the first address, and only
then will the second address be calculated. This feature can be used
to determine the starting line for forwards and backwards searches;
see rules 5. and 6.
Addresses can be omitted on either side of the <comma> or <semicolon>
separator, in which case the resulting address pairs shall be as
follows:
┌──────────┬─────────────┐
│Specified │ Resulting │
├──────────┼─────────────┤
│, │ 1 , $ │
│, addr │ 1 , addr │
│addr , │ addr , addr │
│; │ . ; $ │
│; addr │ . ; addr │
│addr ; │ addr ; addr │
└──────────┴─────────────┘
Any <blank> characters included between addresses, address
separators, or address offsets shall be ignored.
Commands in ed
In the following list of ed commands, the default addresses are shown
in parentheses. The number of addresses shown in the default shall be
the number expected by the command. The parentheses are not part of
the address; they show that the given addresses are the default.
It is generally invalid for more than one command to appear on a
line. However, any command (except e, E, f, q, Q, r, w, and !) can
be suffixed by the letter l, n, or p; in which case, except for the
l, n, and p commands, the command shall be executed and then the new
current line shall be written as described below under the l, n, and
p commands. When an l, n, or p suffix is used with an l, n, or p
command, the command shall write to standard output as described
below, but it is unspecified whether the suffix writes the current
line again in the requested format or whether the suffix has no
effect. For example, the pl command (base p command with an l suffix)
shall either write just the current line or write it twice—once as
specified for p and once as specified for l. Also, the g, G, v, and
V commands shall take a command as a parameter.
Each address component can be preceded by zero or more <blank>
characters. The command letter can be preceded by zero or more
<blank> characters. If a suffix letter (l, n, or p) is given, the
application shall ensure that it immediately follows the command.
The e, E, f, r, and w commands shall take an optional file parameter,
separated from the command letter by one or more <blank> characters.
If changes have been made in the buffer since the last w command that
wrote the entire buffer, ed shall warn the user if an attempt is made
to destroy the editor buffer via the e or q commands. The ed utility
shall write the string:
"?\n"
(followed by an explanatory message if help mode has been enabled via
the H command) to standard output and shall continue in command mode
with the current line number unchanged. If the e or q command is
repeated with no intervening command, it shall take effect.
If a terminal disconnect (see the Base Definitions volume of
POSIX.1‐2008, Chapter 11, General Terminal Interface, Modem
Disconnect and Closing a Device Terminal), is detected:
* If accompanied by a SIGHUP signal, the ed utility shall operate
as described in the ASYNCHRONOUS EVENTS section for a SIGHUP
signal.
* If not accompanied by a SIGHUP signal, the ed utility shall act
as if an end-of-file had been detected on standard input.
If an end-of-file is detected on standard input:
* If the ed utility is in input mode, ed shall terminate input mode
and return to command mode. It is unspecified if any partially
entered lines (that is, input text without a terminating
<newline>) are discarded from the input text.
* If the ed utility is in command mode, it shall act as if a q
command had been entered.
If the closing delimiter of an RE or of a replacement string (for
example, '/') in a g, G, s, v, or V command would be the last
character before a <newline>, that delimiter can be omitted, in which
case the addressed line shall be written. For example, the following
pairs of commands are equivalent:
s/s1/s2 s/s1/s2/p
g/s1 g/s1/p
?s1 ?s1?
If an invalid command is entered, ed shall write the string:
"?\n"
(followed by an explanatory message if help mode has been enabled via
the H command) to standard output and shall continue in command mode
with the current line number unchanged.
Append Command
Synopsis:
(.)a
<text>
.
The a command shall read the given text and append it after the
addressed line; the current line number shall become the address of
the last inserted line or, if there were none, the addressed line.
Address 0 shall be valid for this command; it shall cause the
appended text to be placed at the beginning of the buffer.
Change Command
Synopsis:
(.,.)c
<text>
.
The c command shall delete the addressed lines, then accept input
text that replaces these lines; the current line shall be set to the
address of the last line input; or, if there were none, at the line
after the last line deleted; if the lines deleted were originally at
the end of the buffer, the current line number shall be set to the
address of the new last line; if no lines remain in the buffer, the
current line number shall be set to zero. Address 0 shall be valid
for this command; it shall be interpreted as if address 1 were
specified.
Delete Command
Synopsis:
(.,.)d
The d command shall delete the addressed lines from the buffer. The
address of the line after the last line deleted shall become the
current line number; if the lines deleted were originally at the end
of the buffer, the current line number shall be set to the address of
the new last line; if no lines remain in the buffer, the current line
number shall be set to zero.
Edit Command
Synopsis:
e [file]
The e command shall delete the entire contents of the buffer and then
read in the file named by the pathname file. The current line number
shall be set to the address of the last line of the buffer. If no
pathname is given, the currently remembered pathname, if any, shall
be used (see the f command). The number of bytes read shall be
written to standard output, unless the −s option was specified, in
the following format:
"%d\n", <number of bytes read>
The name file shall be remembered for possible use as a default
pathname in subsequent e, E, r, and w commands. If file is replaced
by '!', the rest of the line shall be taken to be a shell command
line whose output is to be read. Such a shell command line shall not
be remembered as the current file. All marks shall be discarded upon
the completion of a successful e command. If the buffer has changed
since the last time the entire buffer was written, the user shall be
warned, as described previously.
Edit Without Checking Command
Synopsis:
E [file]
The E command shall possess all properties and restrictions of the e
command except that the editor shall not check to see whether any
changes have been made to the buffer since the last w command.
Filename Command
Synopsis:
f [file]
If file is given, the f command shall change the currently remembered
pathname to file; whether the name is changed or not, it shall then
write the (possibly new) currently remembered pathname to the
standard output in the following format:
"%s\n", <pathname>
The current line number shall be unchanged.
Global Command
Synopsis:
(1,$)g/RE/command list
In the g command, the first step shall be to mark every line for
which the line excluding the terminating <newline> matches the given
RE. Then, going sequentially from the beginning of the file to the
end of the file, the given command list shall be executed for each
marked line, with the current line number set to the address of that
line. Any line modified by the command list shall be unmarked. When
the g command completes, the current line number shall have the value
assigned by the last command in the command list. If there were no
matching lines, the current line number shall not be changed. A
single command or the first of a list of commands shall appear on the
same line as the global command. All lines of a multi-line list
except the last line shall be ended with a <backslash> preceding the
terminating <newline>; the a, i, and c commands and associated input
are permitted. The '.' terminating input mode can be omitted if it
would be the last line of the command list. An empty command list
shall be equivalent to the p command. The use of the g, G, v, V, and
! commands in the command list produces undefined results. Any
character other than <space> or <newline> can be used instead of a
<slash> to delimit the RE. Within the RE, the RE delimiter itself can
be used as a literal character if it is preceded by a <backslash>.
Interactive Global Command
Synopsis:
(1,$)G/RE/
In the G command, the first step shall be to mark every line for
which the line excluding the terminating <newline> matches the given
RE. Then, for every such line, that line shall be written, the
current line number shall be set to the address of that line, and any
one command (other than one of the a, c, i, g, G, v, and V commands)
shall be read and executed. A <newline> shall act as a null command
(causing no action to be taken on the current line); an '&' shall
cause the re-execution of the most recent non-null command executed
within the current invocation of G. Note that the commands input as
part of the execution of the G command can address and affect any
lines in the buffer. Any line modified by the command shall be
unmarked. The final value of the current line number shall be the
value set by the last command successfully executed. (Note that the
last command successfully executed shall be the G command itself if a
command fails or the null command is specified.) If there were no
matching lines, the current line number shall not be changed. The G
command can be terminated by a SIGINT signal. Any character other
than <space> or <newline> can be used instead of a <slash> to delimit
the RE and the replacement. Within the RE, the RE delimiter itself
can be used as a literal character if it is preceded by a
<backslash>.
Help Command
Synopsis:
h
The h command shall write a short message to standard output that
explains the reason for the most recent '?' notification. The
current line number shall be unchanged.
Help-Mode Command
Synopsis:
H
The H command shall cause ed to enter a mode in which help messages
(see the h command) shall be written to standard output for all
subsequent '?' notifications. The H command alternately shall turn
this mode on and off; it is initially off. If the help-mode is being
turned on, the H command also explains the previous '?'
notification, if there was one. The current line number shall be
unchanged.
Insert Command
Synopsis:
(.)i
<text>
.
The i command shall insert the given text before the addressed line;
the current line is set to the last inserted line or, if there was
none, to the addressed line. This command differs from the a command
only in the placement of the input text. Address 0 shall be valid for
this command; it shall be interpreted as if address 1 were specified.
Join Command
Synopsis:
(.,.+1)j
The j command shall join contiguous lines by removing the appropriate
<newline> characters. If exactly one address is given, this command
shall do nothing. If lines are joined, the current line number shall
be set to the address of the joined line; otherwise, the current line
number shall be unchanged.
Mark Command
Synopsis:
(.)kx
The k command shall mark the addressed line with name x, which the
application shall ensure is a lowercase letter from the portable
character set. The address "'x" shall then refer to this line; the
current line number shall be unchanged.
List Command
Synopsis:
(.,.)l
The l command shall write to standard output the addressed lines in a
visually unambiguous form. The characters listed in the Base
Definitions volume of POSIX.1‐2008, Table 5-1, Escape Sequences and
Associated Actions ('\\', '\a', '\b', '\f', '\r', '\t', '\v') shall
be written as the corresponding escape sequence; the '\n' in that
table is not applicable. Non-printable characters not in the table
shall be written as one three-digit octal number (with a preceding
<backslash> character) for each byte in the character (most
significant byte first).
Long lines shall be folded, with the point of folding indicated by
<newline> preceded by a <backslash>; the length at which folding
occurs is unspecified, but should be appropriate for the output
device. The end of each line shall be marked with a '$', and '$'
characters within the text shall be written with a preceding
<backslash>. An l command can be appended to any other command other
than e, E, f, q, Q, r, w, or !. The current line number shall be set
to the address of the last line written.
Move Command
Synopsis:
(.,.)maddress
The m command shall reposition the addressed lines after the line
addressed by address. Address 0 shall be valid for address and cause
the addressed lines to be moved to the beginning of the buffer. It
shall be an error if address address falls within the range of moved
lines. The current line number shall be set to the address of the
last line moved.
Number Command
Synopsis:
(.,.)n
The n command shall write to standard output the addressed lines,
preceding each line by its line number and a <tab>; the current line
number shall be set to the address of the last line written. The n
command can be appended to any command other than e, E, f, q, Q, r,
w, or !.
Print Command
Synopsis:
(.,.)p
The p command shall write to standard output the addressed lines; the
current line number shall be set to the address of the last line
written. The p command can be appended to any command other than e,
E, f, q, Q, r, w, or !.
Prompt Command
Synopsis:
P
The P command shall cause ed to prompt with an <asterisk> ('*') (or
string, if −p is specified) for all subsequent commands. The P
command alternatively shall turn this mode on and off; it shall be
initially on if the −p option is specified; otherwise, off. The
current line number shall be unchanged.
Quit Command
Synopsis:
q
The q command shall cause ed to exit. If the buffer has changed since
the last time the entire buffer was written, the user shall be
warned, as described previously.
Quit Without Checking Command
Synopsis:
Q
The Q command shall cause ed to exit without checking whether changes
have been made in the buffer since the last w command.
Read Command
Synopsis:
($)r [file]
The r command shall read in the file named by the pathname file and
append it after the addressed line. If no file argument is given, the
currently remembered pathname, if any, shall be used (see the e and f
commands). The currently remembered pathname shall not be changed
unless there is no remembered pathname. Address 0 shall be valid for
r and shall cause the file to be read at the beginning of the buffer.
If the read is successful, and −s was not specified, the number of
bytes read shall be written to standard output in the following
format:
"%d\n", <number of bytes read>
The current line number shall be set to the address of the last line
read in. If file is replaced by '!', the rest of the line shall be
taken to be a shell command line whose output is to be read. Such a
shell command line shall not be remembered as the current pathname.
Substitute Command
Synopsis:
(.,.)s/RE/replacement/flags
The s command shall search each addressed line for an occurrence of
the specified RE and replace either the first or all (non-overlapped)
matched strings with the replacement; see the following description
of the g suffix. It is an error if the substitution fails on every
addressed line. Any character other than <space> or <newline> can be
used instead of a <slash> to delimit the RE and the replacement.
Within the RE, the RE delimiter itself can be used as a literal
character if it is preceded by a <backslash>. The current line shall
be set to the address of the last line on which a substitution
occurred.
An <ampersand> ('&') appearing in the replacement shall be replaced
by the string matching the RE on the current line. The special
meaning of '&' in this context can be suppressed by preceding it by
<backslash>. As a more general feature, the characters '\n', where n
is a digit, shall be replaced by the text matched by the
corresponding back-reference expression. If the corresponding back-
reference expression does not match, then the characters '\n' shall
be replaced by the empty string. When the character '%' is the only
character in the replacement, the replacement used in the most recent
substitute command shall be used as the replacement in the current
substitute command; if there was no previous substitute command, the
use of '%' in this manner shall be an error. The '%' shall lose its
special meaning when it is in a replacement string of more than one
character or is preceded by a <backslash>. For each <backslash>
encountered in scanning replacement from beginning to end, the
following character shall lose its special meaning (if any). It is
unspecified what special meaning is given to any character other than
<backslash>, '&', '%', or digits.
A line can be split by substituting a <newline> into it. The
application shall ensure it escapes the <newline> in the replacement
by preceding it by <backslash>. Such substitution cannot be done as
part of a g or v command list. The current line number shall be set
to the address of the last line on which a substitution is performed.
If no substitution is performed, the current line number shall be
unchanged. If a line is split, a substitution shall be considered to
have been performed on each of the new lines for the purpose of
determining the new current line number. A substitution shall be
considered to have been performed even if the replacement string is
identical to the string that it replaces.
The application shall ensure that the value of flags is zero or more
of:
count Substitute for the countth occurrence only of the RE found on
each addressed line.
g Globally substitute for all non-overlapping instances of the
RE rather than just the first one. If both g and count are
specified, the results are unspecified.
l Write to standard output the final line in which a
substitution was made. The line shall be written in the
format specified for the l command.
n Write to standard output the final line in which a
substitution was made. The line shall be written in the
format specified for the n command.
p Write to standard output the final line in which a
substitution was made. The line shall be written in the
format specified for the p command.
Copy Command
Synopsis:
(.,.)taddress
The t command shall be equivalent to the m command, except that a
copy of the addressed lines shall be placed after address address
(which can be 0); the current line number shall be set to the address
of the last line added.
Undo Command
Synopsis:
u
The u command shall nullify the effect of the most recent command
that modified anything in the buffer, namely the most recent a, c, d,
g, i, j, m, r, s, t, u, v, G, or V command. All changes made to the
buffer by a g, G, v, or V global command shall be undone as a single
change; if no changes were made by the global command (such as with
g/RE/p), the u command shall have no effect. The current line number
shall be set to the value it had immediately before the command being
undone started.
Global Non-Matched Command
Synopsis:
(1,$)v/RE/command list
This command shall be equivalent to the global command g except that
the lines that are marked during the first step shall be those for
which the line excluding the terminating <newline> does not match the
RE.
Interactive Global Not-Matched Command
Synopsis:
(1,$)V/RE/
This command shall be equivalent to the interactive global command G
except that the lines that are marked during the first step shall be
those for which the line excluding the terminating <newline> does not
match the RE.
Write Command
Synopsis:
(1,$)w [file]
The w command shall write the addressed lines into the file named by
the pathname file. The command shall create the file, if it does not
exist, or shall replace the contents of the existing file. The
currently remembered pathname shall not be changed unless there is no
remembered pathname. If no pathname is given, the currently
remembered pathname, if any, shall be used (see the e and f
commands); the current line number shall be unchanged. If the command
is successful, the number of bytes written shall be written to
standard output, unless the −s option was specified, in the following
format:
"%d\n", <number of bytes written>
If file begins with '!', the rest of the line shall be taken to be a
shell command line whose standard input shall be the addressed lines.
Such a shell command line shall not be remembered as the current
pathname. This usage of the write command with '!' shall not be
considered as a ``last w command that wrote the entire buffer'', as
described previously; thus, this alone shall not prevent the warning
to the user if an attempt is made to destroy the editor buffer via
the e or q commands.
Line Number Command
Synopsis:
($)=
The line number of the addressed line shall be written to standard
output in the following format:
"%d\n", <line number>
The current line number shall be unchanged by this command.
Shell Escape Command
Synopsis:
!command
The remainder of the line after the '!' shall be sent to the command
interpreter to be interpreted as a shell command line. Within the
text of that shell command line, the unescaped character '%' shall be
replaced with the remembered pathname; if a '!' appears as the first
character of the command, it shall be replaced with the text of the
previous shell command executed via '!'. Thus, "!!" shall repeat the
previous !command. If any replacements of '%' or '!' are performed,
the modified line shall be written to the standard output before
command is executed. The ! command shall write:
"!\n"
to standard output upon completion, unless the −s option is
specified. The current line number shall be unchanged.
Null Command
Synopsis:
(.+1)
An address alone on a line shall cause the addressed line to be
written. A <newline> alone shall be equivalent to "+1p". The current
line number shall be set to the address of the written line.
The following exit values shall be returned:
0 Successful completion without any file or command errors.
>0 An error occurred.
When an error in the input script is encountered, or when an error is
detected that is a consequence of the data (not) present in the file
or due to an external condition such as a read or write error:
* If the standard input is a terminal device file, all input shall
be flushed, and a new command read.
* If the standard input is a regular file, ed shall terminate with
a non-zero exit status.
The following sections are informative.
Because of the extremely terse nature of the default error messages,
the prudent script writer begins the ed input commands with an H
command, so that if any errors do occur at least some clue as to the
cause is made available.
In earlier versions of this standard, an obsolescent − option was
described. This is no longer specified. Applications should use the
−s option. Using − as a file operand now produces unspecified
results. This allows implementations to continue to support the
former required behavior.
None.
The initial description of this utility was adapted from the SVID. It
contains some features not found in Version 7 or BSD-derived systems.
Some of the differences between the POSIX and BSD ed utilities
include, but need not be limited to:
* The BSD − option does not suppress the '!' prompt after a !
command.
* BSD does not support the special meanings of the '%' and '!'
characters within a ! command.
* BSD does not support the addresses ';' and ','.
* BSD allows the command/suffix pairs pp, ll, and so on, which are
unspecified in this volume of POSIX.1‐2008.
* BSD does not support the '!' character part of the e, r, or w
commands.
* A failed g command in BSD sets the line number to the last line
searched if there are no matches.
* BSD does not default the command list to the p command.
* BSD does not support the G, h, H, n, or V commands.
* On BSD, if there is no inserted text, the insert command changes
the current line to the referenced line −1; that is, the line
before the specified line.
* On BSD, the join command with only a single address changes the
current line to that address.
* BSD does not support the P command; moreover, in BSD it is
synonymous with the p command.
* BSD does not support the undo of the commands j, m, r, s, or t.
* The Version 7 ed command W, and the BSD ed commands W, wq, and z
are not present in this volume of POSIX.1‐2008.
The −s option was added to allow the functionality of the removed −
option in a manner compatible with the Utility Syntax Guidelines.
In early proposals there was a limit, {ED_FILE_MAX}, that described
the historical limitations of some ed utilities in their handling of
large files; some of these have had problems with files larger than
100000 bytes. It was this limitation that prompted much of the desire
to include a split command in this volume of POSIX.1‐2008. Since this
limit was removed, this volume of POSIX.1‐2008 requires that
implementations document the file size limits imposed by ed in the
conformance document. The limit {ED_LINE_MAX} was also removed;
therefore, the global limit {LINE_MAX} is used for input and output
lines.
The manner in which the l command writes non-printable characters was
changed to avoid the historical backspace-overstrike method. On video
display terminals, the overstrike is ambiguous because most terminals
simply replace overstruck characters, making the l format not useful
for its intended purpose of unambiguously understanding the content
of the line. The historical <backslash>-escapes were also ambiguous.
(The string "a\0011" could represent a line containing those six
characters or a line containing the three characters 'a', a byte with
a binary value of 1, and a 1.) In the format required here, a
<backslash> appearing in the line is written as "\\" so that the
output is truly unambiguous. The method of marking the ends of lines
was adopted from the ex editor and is required for any line ending in
<space> characters; the '$' is placed on all lines so that a real '$'
at the end of a line cannot be misinterpreted.
Earlier versions of this standard allowed for implementations with
bytes other than eight bits, but this has been modified in this
version.
The description of how a NUL is written was removed. The NUL
character cannot be in text files, and this volume of POSIX.1‐2008
should not dictate behavior in the case of undefined, erroneous
input.
Unlike some of the other editing utilities, the filenames accepted by
the E, e, R, and r commands are not patterns.
Early proposals stated that the −p option worked only when standard
input was associated with a terminal device. This has been changed to
conform to historical implementations, thereby allowing applications
to interpose themselves between a user and the ed utility.
The form of the substitute command that uses the n suffix was limited
in some historical documentation (where this was described
incorrectly as ``backreferencing''). This limit has been omitted
because there is no reason why an editor processing lines of
{LINE_MAX} length should have this restriction. The command
s/x/X/2047 should be able to substitute the 2047th occurrence of 'x'
on a line.
The use of printing commands with printing suffixes (such as pn, lp,
and so on) was made unspecified because BSD-based systems allow this,
whereas System V does not.
Some BSD-based systems exit immediately upon receipt of end-of-file
if all of the lines in the file have been deleted. Since this volume
of POSIX.1‐2008 refers to the q command in this instance, such
behavior is not allowed.
Some historical implementations returned exit status zero even if
command errors had occurred; this is not allowed by this volume of
POSIX.1‐2008.
Some historical implementations contained a bug that allowed a single
<period> to be entered in input mode as <backslash> <period>
<newline>. This is not allowed by ed because there is no description
of escaping any of the characters in input mode; <backslash>
characters are entered into the buffer exactly as typed. The typical
method of entering a single <period> has been to precede it with
another character and then use the substitute command to delete that
character.
It is difficult under some modes of some versions of historical
operating system terminal drivers to distinguish between an end-of-
file condition and terminal disconnect. POSIX.1‐2008 does not require
implementations to distinguish between the two situations, which
permits historical implementations of the ed utility on historical
platforms to conform. Implementations are encouraged to distinguish
between the two, if possible, and take appropriate action on terminal
disconnect.
Historically, ed accepted a zero address for the a and r commands in
order to insert text at the start of the edit buffer. When the buffer
was empty the command .= returned zero. POSIX.1‐2008 requires
conformance to historical practice.
For consistency with the a and r commands and better user
functionality, the i and c commands must also accept an address of 0,
in which case 0i is treated as 1i and likewise for the c command.
All of the following are valid addresses:
+++ Three lines after the current line.
/pattern/− One line before the next occurrence of pattern.
−2 Two lines before the current line.
3 −−−− 2 Line one (note the intermediate negative address).
1 2 3 Line six.
Any number of addresses can be provided to commands taking addresses;
for example, "1,2,3,4,5p" prints lines 4 and 5, because two is the
greatest valid number of addresses accepted by the print command.
This, in combination with the <semicolon> delimiter, permits users to
create commands based on ordered patterns in the file. For example,
the command "3;/foo/;+2p" will display the first line after line 3
that contains the pattern foo, plus the next two lines. Note that the
address "3;" must still be evaluated before being discarded, because
the search origin for the "/foo/" command depends on this.
Historically, ed disallowed address chains, as discussed above,
consisting solely of <comma> or <semicolon> separators; for example,
",,," or ";;;" were considered an error. For consistency of address
specification, this restriction is removed. The following table lists
some of the address forms now possible:
┌────────┬───────┬───────┬────────────┬───────────────────────┐
│Address │ Addr1 │ Addr2 │ Status │ Comment │
├────────┼───────┼───────┼────────────┼───────────────────────┤
│7, │ 7 │ 7 │ Historical │ │
│7,5, │ 5 │ 5 │ Historical │ │
│7,5,9 │ 5 │ 9 │ Historical │ │
│7,9 │ 7 │ 9 │ Historical │ │
│7,+ │ 7 │ 8 │ Historical │ │
│, │ 1 │ $ │ Historical │ │
│,7 │ 1 │ 7 │ Extension │ │
│,, │ $ │ $ │ Extension │ │
│,; │ $ │ $ │ Extension │ │
│7; │ 7 │ 7 │ Historical │ │
│7;5; │ 5 │ 5 │ Historical │ │
│7;5;9 │ 5 │ 9 │ Historical │ │
│7;5,9 │ 5 │ 9 │ Historical │ │
│7;$;4 │ $ │ 4 │ Historical │ Valid, but erroneous. │
│7;9 │ 7 │ 9 │ Historical │ │
│7;+ │ 7 │ 8 │ Historical │ │
│; │ . │ $ │ Historical │ │
│;7 │ . │ 7 │ Extension │ │
│;; │ $ │ $ │ Extension │ │
│;, │ $ │ $ │ Extension │ │
└────────┴───────┴───────┴────────────┴───────────────────────┘
Historically, ed accepted the '^' character as an address, in which
case it was identical to the <hyphen> character. POSIX.1‐2008 does
not require or prohibit this behavior.
None.
Section 1.4, Utility Description Defaults, ex(1p), sed(1p), sh(1p),
vi(1p)
The Base Definitions volume of POSIX.1‐2008, Table 5-1, Escape
Sequences and Associated Actions, Chapter 8, Environment Variables,
Section 9.3, Basic Regular Expressions, Chapter 11, General Terminal
Interface, Section 12.2, Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ED(1P)
Pages that refer to this page: diff(1p), ex(1p), lex(1p), mailx(1p), more(1p), patch(1p), pax(1p), sed(1p), vi(1p)
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