ed(1p) — Linux manual page

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

ED(1P)                  POSIX Programmer's Manual                 ED(1P)

PROLOG         top

       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         top

       ed — edit text

SYNOPSIS         top

       ed [-p string] [-s] [file]

DESCRIPTION         top

       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         top

       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         top

       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         top

       The standard input shall be a text file consisting of commands,
       as described in the EXTENDED DESCRIPTION section.

INPUT FILES         top

       The input files shall be text files.

ENVIRONMENT VARIABLES         top

       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         top

       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         top

       Various editing commands and the prompting feature (see -p) write
       to standard output, as described in the EXTENDED DESCRIPTION
       section.

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       The output files shall be text files whose formats are dependent
       on the editing commands given.

EXTENDED DESCRIPTION         top

       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 ('$') 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-minus> character ('-')
           followed by a decimal number shall address the current line
           plus or minus the number. A <plus-sign> or <hyphen-minus>
           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-minus> 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-minus> 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.1‐2017, 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.1‐2017, 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.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion without any file or command errors.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       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.

APPLICATION USAGE         top

       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.

EXAMPLES         top

       None.

RATIONALE         top

       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.1‐2017.

        *  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.1‐2017.

       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.1‐2017. Since this limit was removed, this volume
       of POSIX.1‐2017 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.1‐2017 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.1‐2017 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.1‐2017.

       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-minus> character.
       POSIX.1‐2008 does not require or prohibit this behavior.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 1.4, Utility Description Defaults, ex(1p), sed(1p),
       sh(1p), vi(1p)

       The Base Definitions volume of POSIX.1‐2017, 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

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  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.opengroup.org/unix/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               2017                            ED(1P)

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