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IEEE P1003.2 Draft 11.2 - September 1991
Copyright (c) 1991 by the
Institute of Electrical and Electronics Engineers, Inc.
345 East 47th Street
New York, NY 10017, USA
All rights reserved as an unpublished work.
This is an unapproved and unpublished IEEE Standards Draft,
subject to change. The publication, distribution, or
copying of this draft, as well as all derivative works based
on this draft, is expressly prohibited except as set forth
below.
Permission is hereby granted for IEEE Standards Committee
participants to reproduce this document for purposes of IEEE
standardization activities only, and subject to the
restrictions contained herein.
Permission is hereby also granted for member bodies and
technical committees of ISO and IEC to reproduce this
document for purposes of developing a national position,
subject to the restrictions contained herein.
Permission is hereby also granted to the preceding entities
to make limited copies of this document in an electronic
form only for the stated activities.
The following restrictions apply to reproducing or
transmitting the document in any form: 1) all copies or
portions thereof must identify the document's IEEE project
number and draft number, and must be accompanied by this
entire notice in a prominent location; 2) no portion of this
document may be redistributed in any modified or abridged
form without the prior approval of the IEEE Standards
Department.
Other entities seeking permission to reproduce this
document, or any portion thereof, for standardization or
other activities, must contact the IEEE Standards Department
for the appropriate license.
Use of information contained in this unapproved draft is at
your own risk.
IEEE Standards Department
Copyright and Permissions
445 Hoes Lane, P.O. Box 1331
Piscataway, NJ 08855-1331, USA
+1 (908) 562-3800
+1 (908) 562-1571 [FAX]
P1003.2 Draft 11.2
ISO/IEC CD 9945-2.2
4.20 ed - Edit text
4.20.1 Synopsis
ed [-p _s_t_r_i_n_g] [-s] [_f_i_l_e]
_O_b_s_o_l_e_s_c_e_n_t _V_e_r_s_i_o_n:
ed [-p _s_t_r_i_n_g] [-] [_f_i_l_e]
4.20.2 Description
The ed utility is a line-oriented text editor that shall use two modes:
_c_o_m_m_a_n_d _m_o_d_e and _i_n_p_u_t _m_o_d_e. In command mode the input characters shall
be interpreted as commands, and in input mode they shall be interpreted
as text. See 4.20.7.
4.20.3 Options
The ed utility shall conform to the utility argument syntax guidelines
described in 2.10.2, except for its nonstandard usage of - in the
obsolescent version.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 479
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
The following options shall be supported by the implementation:
-p _s_t_r_i_n_g Use _s_t_r_i_n_g 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 !_c_o_m_m_a_n_d.
- (Obsolescent.) Equivalent to the -s option.
4.20.4 Operands
The following operand shall be supported by the implementation:
_f_i_l_e If the _f_i_l_e argument is given, ed shall simulate an e
command on the file named by the pathname, _f_i_l_e, before
accepting commands from the standard input.
4.20.5 External Influences
4.20.5.1 Standard Input
The standard input shall be a text file consisting of commands, as
described in 4.20.7.
4.20.5.2 Input Files
The input files shall be text files.
4.20.5.3 Environment Variables
The following environment variables shall affect the execution of ed:
HOME This variable shall determine the pathname of the
user's home directory.
LANG This variable shall determine the locale to use for
the locale categories when both LC_ALL and the
corresponding environment variable (beginning with
LC_) do not specify a locale. See 2.6.
LC_ALL This variable shall determine the locale to be used
to override any values for locale categories
specified by the settings of LANG or any
environment variables beginning with LC_.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
480 4 Execution Environment Utilities
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LC_COLLATE This variable shall determine the locale for the
behavior of ranges, equivalence classes, and
multicharacter collating elements within regular
expressions.
LC_CTYPE This variable shall determine the locale for the
interpretation of sequences of bytes of text data
as characters (e.g., single- versus multibyte
characters in arguments and input files), the
behavior of character classes within regular
expressions.
LC_MESSAGES This variable shall determine the language in which
messages should be written.
4.20.5.4 Asynchronous Events
The ed utility shall take the standard action for all signals (see
2.11.5.4), 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
4.20.7).
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 returning to command mode.
4.20.6 External Effects
4.20.6.1 Standard Output
Various editing commands and the prompting feature (see -p) write to
standard output, as described in 4.20.7.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 481
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
4.20.6.2 Standard Error
Used only for diagnostic messages.
4.20.6.3 Output Files
The output files shall be text files whose formats are dependent on the
editing commands given.
4.20.7 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 _b_u_f_f_e_r in this
clause, although no attempt is made to imply a specific implementation.
Commands to ed have a simple and regular structure: zero, one, or two
_a_d_d_r_e_s_s_e_s followed by a single-character _c_o_m_m_a_n_d, 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 _i_n_p_u_t _m_o_d_e.
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.
_4._2_0._7._1 ed _R_e_g_u_l_a_r _E_x_p_r_e_s_s_i_o_n_s
The ed utility shall support basic regular expressions, as described in
2.8.3. Since regular expressions in ed are always matched against single
lines, 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.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
482 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
_4._2_0._7._2 ed _A_d_d_r_e_s_s_e_s
Addressing in ed relates to the _c_u_r_r_e_n_t _l_i_n_e. Generally, the current
line is the last line affected by a command. The _c_u_r_r_e_n_t _l_i_n_e _n_u_m_b_e_r is
the address (line number) of the current line. The exact effect on the
current line number is discussed under the description of each command.
The f, h, H, k, P, w, =, and ! commands shall not modify the current line
number.
Addresses are constructed as follows:
(1) The character . (period) shall address the current line.
(2) The character $ shall address the last line of the buffer.
(3) A positive decimal number _n shall address the _n-th line of the
buffer. The first line in the buffer is line number 1.
(4) '_x shall address the line marked with the mark name character _x,
which shall be a lowercase letter from the portable character
set. Lines can be marked with the k command described in
4.20.7.3.13.
(5) An RE enclosed by slashes (/) shall address the first line found
by searching forward from the line following the current line
toward the end of the buffer and stopping at the first line
containing a string matching the RE. [As stated in 4.20.7.1, an
address consisting of a null RE delimited by slashes (//) shall
address the next line containing the last RE encountered.] 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. Within the RE, the sequence
\/ shall represent a literal slash instead of the RE delimiter.
(6) An RE enclosed in question-marks (?) shall address the first
line found by searching backward from the line preceding the
current line toward the beginning of the buffer and stopping at
the first line containing a string matching the RE. If
necessary, the search wraps around to the end of the buffer and
continues up to and including the current line. Within the RE,
the sequence \? shall represent a literal question-mark instead
of the RE delimiter.
(7) An address followed by a plus sign (+) or a minus sign (-)
followed by a decimal number specifies that address plus
(respectively minus) the indicated number of lines. The plus
sign can be omitted.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 483
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
(8) If an address begins with + or -, the addition or subtraction is
taken with respect to the current line number; for example, -5
is understood to mean .-5.
(9) If an address ends with + or -, then 1 shall be added to or
subtracted from the address, respectively. As a consequence of
this rule and of rule (8) immediately above, the address - shall
refer to the line preceding the current line. Moreover,
trailing + and - characters shall have a cumulative effect, so
-- shall refer to the current line number less 2.
(10) A comma (,) shall stand for the address pair 1,$, while a
semicolon (;) shall stand for the pair .,$.
Commands require zero, one, or two addresses. Commands that require no
addresses shall regard the presence of an address as an error. Commands
that accept one or two addresses assume default addresses when no
addresses are given, as described in 4.20.7.3. If one address is given
to a command that allows two addresses, the command shall operate as if
it were specified as:
_g_i_v_e_n__a_d_d_r_e_s_s;. _c_o_m_m_a_n_d
If more addresses are given than such a command requires, the results are
undefined.
Typically, addresses are separated from each other by a comma. They can
also be separated by a semicolon. In the latter case, the current line
number (.) shall be set to the first address, and only then shall the
second address be calculated. This feature can be used to determine the
starting line for forward and backward searches [see rules (5) and (6)
above]. The second address of any two-address sequence shall correspond
to a line that does not precede, in the buffer, the line corresponding to
the first address.
_4._2_0._7._3 ed _C_o_m_m_a_n_d_s
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 1
shall be written as described below under the l, n, and p commands. When 1
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
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
484 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
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
shall 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>_s. The
command letter can be preceded by zero or more <blank>_s. If a suffix
letter (l, n, or p) is given, it shall immediately follow the command.
The e, E, f, r, and w commands shall take an optional _f_i_l_e parameter,
separated from the command letter by one or more <blank>s.
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 _h_e_l_p _m_o_d_e 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 an end-of-file is detected on standard input when a command is
expected, the ed utility shall act as if a q command had been entered.
If the closing delimiter of an RE or of a replacement string (e.g., /) 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 _h_e_l_p _m_o_d_e has been enabled via the
H command) to standard output and shall continue in command mode with the
current line number unchanged.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 485
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
4.20.7.3.1 Append Command
_S_y_n_o_p_s_i_s: (.)a
<_t_e_x_t>
.
The _a_p_p_e_n_d 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.
4.20.7.3.2 Change Command
_S_y_n_o_p_s_i_s: (.,.)c 1
<_t_e_x_t>
.
The _c_h_a_n_g_e 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.
4.20.7.3.3 Delete Command
_S_y_n_o_p_s_i_s: (.,.)d
The _d_e_l_e_t_e 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.
4.20.7.3.4 Edit Command
_S_y_n_o_p_s_i_s: e [_f_i_l_e]
The _e_d_i_t command shall delete the entire contents of the buffer and then
read in the file named by the pathname _f_i_l_e. 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:
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
486 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
"%d\n", <_n_u_m_b_e_r _o_f _b_y_t_e_s _r_e_a_d>
The name _f_i_l_e shall be remembered for possible use as a default pathname
in subsequent e, E, r, and w commands. If _f_i_l_e 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 _f_i_l_e. 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.
4.20.7.3.5 Edit Without Checking Command
_S_y_n_o_p_s_i_s: E [_f_i_l_e]
The _E_d_i_t command shall possess all properties and restrictions of the e
command except that the editor shall not check to see if any changes have
been made to the buffer since the last w command.
4.20.7.3.6 File-Name Command
_S_y_n_o_p_s_i_s: f [_f_i_l_e]
If _f_i_l_e is given, the file-name command shall change the currently
remembered pathname to _f_i_l_e; whether the name is changed or not, it then
shall write the (possibly new) currently remembered pathname to the
standard output in the following format:
"%s\n", <_p_a_t_h_n_a_m_e>
The current line number shall be unchanged.
4.20.7.3.7 Global Command
_S_y_n_o_p_s_i_s: (1,$)g/_R_E/_c_o_m_m_a_n_d _l_i_s_t
In the _g_l_o_b_a_l command, the first step shall be to mark every line that
matches the given _R_E. Then, for every such line, the given _c_o_m_m_a_n_d _l_i_s_t
shall be executed with the current line number set to the address of that
line. When the g command completes, the current line number shall have
the value assigned by the last command in the command list. If there
were no matching lines, the current line number shall not be changed. A
single command or the first of a list of commands shall appear on the
same line as the global command. All lines of a multiline list except
the last line shall be ended with a backslash; the a, i, and c commands
and associated input are permitted. The . terminating input mode can be
omitted if it would be the last line of the _c_o_m_m_a_n_d _l_i_s_t. An empty
_c_o_m_m_a_n_d _l_i_s_t shall be equivalent to the p command. The use of the g, G,
v, V, and ! commands in the _c_o_m_m_a_n_d _l_i_s_t produces undefined results. Any
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 487
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
character other than <space> or <newline> can be used instead of a slash
to delimit the _R_E. Within the RE, the RE delimiter itself can be used as
a literal character if it is preceded by a backslash.
4.20.7.3.8 Interactive Global Command
_S_y_n_o_p_s_i_s: (1,$)G/_R_E/
In the _i_n_t_e_r_a_c_t_i_v_e _g_l_o_b_a_l command, the first step shall be to mark every
line that matches the given _R_E. 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) can be input and shall be executed. A <newline> shall
act as a null command (causing no action to be taken on the current
line); an & shall cause the reexecution of the most recent nonnull
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. 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
_R_E and the replacement. Within the RE, the RE delimiter itself can be
used as a literal character if it is preceded by a backslash.
4.20.7.3.9 Help Command
_S_y_n_o_p_s_i_s: h
The _h_e_l_p 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.
4.20.7.3.10 Help-Mode Command
_S_y_n_o_p_s_i_s: H
The _H_e_l_p 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 shall be initially off. If the help-mode is being
turned on, the H command also shall explain the previous ? notification,
if there was one. The current line number shall be unchanged.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
488 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
4.20.7.3.11 Insert Command
_S_y_n_o_p_s_i_s: (.)i
<_t_e_x_t>
.
The _i_n_s_e_r_t command shall insert the given text before the addressed line;
. shall be left at the last inserted line, or, if there was none, at the
addressed line. This command differs from the a command only in the
placement of the input text. Address 0 shall be invalid for this
command.
4.20.7.3.12 Join Command
_S_y_n_o_p_s_i_s: (.,.+1)j
The _j_o_i_n 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.
4.20.7.3.13 Mark Command
_S_y_n_o_p_s_i_s: (.)k_x
The _m_a_r_k command shall mark the addressed line with name _x, which shall
be a lowercase letter from the portable character set. The address '_x
then shall refer to this line; the current line number shall be
unchanged.
4.20.7.3.14 List Command
_S_y_n_o_p_s_i_s: (.,.)l
The _l_i_s_t command shall write to standard output the addressed lines in a 1
visually unambiguous form. The characters listed in Table 2-15 (see 1
2.12) shall be written as the corresponding escape sequence. 1
Nonprintable characters not in Table 2-15 shall be written as one three- 1
digit octal number (with a preceding <backslash>) for each byte in the 1
character (most significant byte first). If the size of a byte on the 1
system is greater than nine bits, the format used for nonprintable 1
characters is implementation defined. 1
Long lines shall be folded, with the point of folding indicated by 1
writing <backslash><newline>; the length at which folding occurs is 1
unspecified, but should be appropriate for the output device. The end of 1
each line shall be marked with a $. An l command can be appended to any 1
other command other than e, E, f, q, Q, r, w, or !. The current line
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 489
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
number shall be set to the address of the last line written.
4.20.7.3.15 Move Command
_S_y_n_o_p_s_i_s: (.,.)m_a_d_d_r_e_s_s
The _m_o_v_e command shall reposition the addressed line(s) after the line
addressed by _a_d_d_r_e_s_s. Address 0 shall be valid for _a_d_d_r_e_s_s and cause the
addressed line(s) to be moved to the beginning of the buffer. It shall
be an error if address _a_d_d_r_e_s_s falls within the range of moved lines.
The current line number shall be set to the address of the last line
moved.
4.20.7.3.16 Number Command
_S_y_n_o_p_s_i_s: (.,.)n
The _n_u_m_b_e_r command shall write to standard output the addressed lines,
preceding each line by its line number and a <tab> character; the current
line number shall be set to the address of the last line written. The n
command can be appended to any other command other than e, E, f, q, Q, r,
w, or !.
4.20.7.3.17 Print Command
_S_y_n_o_p_s_i_s: (.,.)p
The _p_r_i_n_t 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 other command other than e, E, f, q,
Q, r, w, or !.
4.20.7.3.18 Prompt Command
_S_y_n_o_p_s_i_s: P
The _P_r_o_m_p_t command shall cause ed to prompt with an asterisk (*) (or
_s_t_r_i_n_g, if -p is specified) for all subsequent commands. The P command
alternately 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.
4.20.7.3.19 Quit Command
_S_y_n_o_p_s_i_s: q
The _q_u_i_t 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.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
490 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
4.20.7.3.20 Quit Without Checking Command
_S_y_n_o_p_s_i_s: Q
The _Q_u_i_t command shall cause ed to exit without checking if changes have
been made in the buffer since the last w command.
4.20.7.3.21 Read Command
_S_y_n_o_p_s_i_s: ($)r [_f_i_l_e]
The _r_e_a_d command shall read in the file named by the pathname _f_i_l_e and
append it after the addressed line. If no _f_i_l_e argument is given, the
currently remembered pathname, if any, shall be used (see 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", <_n_u_m_b_e_r _o_f _b_y_t_e_s _r_e_a_d>
The current line number shall be set to the address of the last line read
in. If _f_i_l_e 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.
4.20.7.3.22 Substitute Command
_S_y_n_o_p_s_i_s: (.,.)s/_R_E/_r_e_p_l_a_c_e_m_e_n_t/_f_l_a_g_s
The _s_u_b_s_t_i_t_u_t_e command shall search each addressed line for an occurrence
of the specified RE and replace either the first or all (nonoverlapped)
matched strings with the _r_e_p_l_a_c_e_m_e_n_t; 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 _R_E 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 _r_e_p_l_a_c_e_m_e_n_t 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 backreference expression (see
2.8.3.3). When the character % is the only character in the _r_e_p_l_a_c_e_m_e_n_t,
the _r_e_p_l_a_c_e_m_e_n_t used in the most recent substitute command shall be used
as the _r_e_p_l_a_c_e_m_e_n_t in the current substitute command; if there was no
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
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P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
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.
A line can be split by substituting a <newline> character into it. The 1
application shall escape the <newline> in the _r_e_p_l_a_c_e_m_e_n_t by preceding it 1
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 value of _f_l_a_g_s shall be zero or more of:
_c_o_u_n_t Substitute for the _c_o_u_n_tth occurrence only of the _R_E found on
each addressed line.
g Globally substitute for all nonoverlapping instances of the
_R_E rather than just the first one. If both g and _c_o_u_n_t 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.
4.20.7.3.23 Copy Command
_S_y_n_o_p_s_i_s: (.,.)t_a_d_d_r_e_s_s
The t command shall be equivalent to the m command, except that a copy of
the addressed lines shall be placed after address _a_d_d_r_e_s_s (which can be
0); the current line number shall be set to the address of the last line
added.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
492 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
4.20.7.3.24 Undo Command
_S_y_n_o_p_s_i_s: u
The _u_n_d_o 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 1
g, G, v, or V global command shall be ``undone'' as a single change; if 1
no changes were made by the global command (such as with g/_R_E/p), the u 1
command shall have no effect. The current line number shall be set to 1
the value it had immediately before the command being undone started.
4.20.7.3.25 Global Non-Matched Command
_S_y_n_o_p_s_i_s: (1,$)v/_R_E/_c_o_m_m_a_n_d _l_i_s_t
This command shall be equivalent to the global command g except that the
lines that are marked during the first step shall be those that do not
match the RE.
4.20.7.3.26 Interactive Global Not-Matched Command
_S_y_n_o_p_s_i_s: (1,$)V/_R_E/
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 that do not match the RE.
4.20.7.3.27 Write Command
_S_y_n_o_p_s_i_s: (1,$)w [_f_i_l_e]
The _w_r_i_t_e command shall write the addressed lines into the file named by
the pathname _f_i_l_e. The command shall create the file, if it does not
exist, or shall replace the contents of the existing file. The currently
remembered pathname shall not be changed unless there is no remembered
pathname. If no pathname is given, the currently remembered pathname, if
any, shall be used (see e and f commands); the current line number shall
be unchanged. If the command is successful, the number of bytes written
shall be written to standard output, unless the -s option was specified,
in the following format:
"%d\n", <_n_u_m_b_e_r _o_f _b_y_t_e_s _w_r_i_t_t_e_n>
If _f_i_l_e begins with !, the rest of the line shall be taken to be a shell
command line whose standard input shall be the addressed lines. Such a
shell command line shall not be remembered as the current pathname. This 1
usage of the write command with ! shall not be considered as a ``last w 1
command that wrote the entire buffer,'' as described previously; thus, 1
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 493
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
this alone shall not prevent the warning to the user if an attempt is 1
made to destroy the editor buffer via the e or q commands. 1
4.20.7.3.28 Line Number Command
_S_y_n_o_p_s_i_s: ($)=
The line number of the addressed line shall be written to standard output
in the following format:
"%d\n", <_l_i_n_e _n_u_m_b_e_r>
The current line number shall be unchanged by this command.
4.20.7.3.29 Shell Escape Command
_S_y_n_o_p_s_i_s: !_c_o_m_m_a_n_d
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 !_c_o_m_m_a_n_d. If 2
any replacements of % and/or ! are performed, the modified line shall be 2
written to the standard output before _c_o_m_m_a_n_d is executed. The ! command 2
shall write 2
"!\n"
to standard output upon completion, unless the -s option is specified.
The current line number shall be unchanged.
4.20.7.3.30 Null Command
_S_y_n_o_p_s_i_s: (.+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.
4.20.8 Exit Status
The ed utility shall exit with one of the following values:
0 Successful completion without any file or command errors.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
494 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
>0 An error occurred.
4.20.9 Consequences of Errors
When an error in the input script is encountered, or when an error is 1
detected that is a consequence of the data (not) present in the file or 1
due to an external condition such as a read or write error: 1
- If the standard input is a terminal device file, all input shall be 2
flushed, and a new command read. 2
- If the standard input is a regular file, ed shall terminate with a 2
nonzero exit status. 2
BEGIN_RATIONALE 2
4.20.10 Rationale. (_T_h_i_s _s_u_b_c_l_a_u_s_e _i_s _n_o_t _a _p_a_r_t _o_f _P_1_0_0_3._2)
_E_x_a_m_p_l_e_s_,__U_s_a_g_e
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 the POSIX.2 ed because there is no description of
escaping any of the characters in input mode; backslashes 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.
Because of the extremely terse nature of the default error messages, the 1
prudent script writer will begin the ed input commands with an H command, 1
so that if any errors do occur at least some clue as to the cause will be 1
made available. 1
_H_i_s_t_o_r_y__o_f__D_e_c_i_s_i_o_n_s__M_a_d_e
The initial description of this utility was adapted from the _S_V_I_D. It
contains some features not found in Version 7 or BSD-derived systems.
Some of the differences between the POSIX.2 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 _a_d_d_r_e_s_s_e_s ; and ,.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 495
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
- BSD allows the command/suffix pairs pp, ll, etc., which are
unspecified in POSIX.2.
- 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; i.e., 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 _u_n_d_o of the commands j, m, r, s, or t.
- The BSD ed commands W, wq, and z are not present in POSIX.2.
The -s option was added to allow the functionality of the - option in a
manner compatible with the Utility Syntax Guidelines. It is the intent
of the working group that portable applications use the -s option, and
that in the future the - option be removed from the standard.
Prior to Draft 8 there was a limit, {ED_FILE_MAX}, which described the
historical limitations of some ed utilities in their handling of large
files; some of these have had problems with files in the >100KB range.
It was this limitation that prompted much of the desire to include a
split command in the standard. Since this limit was removed, the
standard 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 \{_m,_n\} notation was removed from the description of regular
expressions because this functionality is now described in 2.8.3.
The manner in which the l command writes nonprintable characters was
changed to avoid the historical backspace-overstrike method. On video
display terminals, the overstrike is ambiguous because most terminals 1
simply replace overstruck characters, making the l format not useful for 1
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
496 4 Execution Environment Utilities
Part 2: SHELL AND UTILITIES P1003.2/D11.2
its intended purpose of unambiguously understanding the content of the 1
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
will be written as "\\" so that the output is truly unambiguous. The 1
method of marking the ends of lines was adopted from the ex editor (see 1
the User Portability Extension) and is required for any line ending in 1
<space>_s; the $ is placed on all lines so that a real $ at the end of a 1
line cannot be misinterpreted. 1
Systems with bytes too large to fit into three octal digits must devise 1
other means of displaying nonprintable characters. Consideration was 1
given to requiring that the number of octal digits be large enough to 1
hold a byte, but this seemed to be too confusing for applications on the 1
vast majority of systems where three digits are adequate. It would be 1
theoretically possible for the application to use the getconf utility to 1
find out the {CHAR_BIT} value and deal with such an algorithm; however, 1
there is really no portable way that an application can use the octal 1
values of the bytes across various coded character sets anyway, so the 1
additional specification did not seem worth the effort. 1
The description of how a NUL is written was removed. The NUL character
cannot be in text files, and the standard should not dictate behavior in
the case of undefined, erroneous input.
The text requiring filenames accepted by the E, e, R, and r commands to
be patterns was removed due to balloting objections that this was
undesirable and not existing practice.
The -p option in Drafts 8 and 9 said that it only worked when standard
input was associated with a terminal device. This has been changed to
conform to existing 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 to
the first 512 matches in a previous draft (where this was described
incorrectly as ``backreferencing''). This limit has been removed because
there is no reason 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,
etc.) 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 had been deleted. Since POSIX.2 refers to
the q command in this instance, such behavior is not allowed.
Copyright c 1991 IEEE. All rights reserved.
This is an unapproved IEEE Standards Draft, subject to change.
4.20 ed - Edit text 497
P1003.2/D11.2 INFORMATION TECHNOLOGY--POSIX
Some historical implementations returned exit status zero even if command
errors had occurred; this is not allowed by POSIX.2.
END_RATIONALE
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