NAME
     ed - text editor

SYNOPSIS
     ed [ - ] [ name ]

DESCRIPTION
     Ed is the standard text editor.

     If a name argument is given, ed simulates an e command (see
     below) on the named file; that is to say, the file is read
     into ed's buffer so that it can be edited.  The optional -
     suppresses the printing of character counts by e, r, and w
     commands.

     Ed operates on a copy of any file it is editing; changes
     made in the copy have no effect on the file until a w
     (write) command is given.  The copy of the text being edited
     resides in a temporary file called the buffer.  There is
     only one buffer.

     Commands to ed have a simple and regular structure: zero or
     more addresses followed by a single character command, pos-
     sibly followed by parameters to the command.  These
     addresses specify one or more lines in the buffer.  Every
     command which requires addresses has default addresses, so
     that the addresses can often be omitted.

     In general, only one command may appear on a line.  Certain
     commands allow the input of text.  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 com-
     mands are recognized; all input is merely collected.  Input
     mode is left by typing a period `.' alone at the beginning
     of a line.

     Ed supports a limited form of regular expression notation.
     A regular expression specifies a set of strings of charac-
     ters.  A member of this set of strings is said to be matched
     by the regular expression.  The regular expressions allowed
     by ed are constructed as follows:

     1. An ordinary character (not one of those discussed below)
        is a regular expression and matches that character.

     2. A circumflex `^' at the beginning of a regular expression
        matches the empty string at the beginning of a line.

     3. A currency symbol `$' at the end of a regular expression
        matches the null character at the end of a line.

     4. A period `.' matches any character except a new-line
        character.

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     5. A regular expression followed by an asterisk `*' matches
        any number of adjacent occurrences (including zero) of
        the regular expression it follows.

     6. A string of characters enclosed in square brackets `[ ]'
        matches any character in the string but no others.  If,
        however, the first character of the string is a circum-
        flex `^' the regular expression matches any character
        except new-line and the characters in the string.

     7. The concatenation of regular expressions is a regular
        expression which matches the concatenation of the strings
        matched by the components of the regular expression.

     8. A regular expression enclosed between the sequences `\('
        and `\)'is identical to the unadorned expression; the
        construction has side effects discussed under the s com-
        mand.

     9. The null regular expression standing alone is equivalent
        to the last regular expression encountered.

     Regular expressions are used in addresses to specify lines
     and in one command (see s below) to specify a portion of a
     line which is to be replaced.  If it is desired to use one
     of the regular expression metacharacters as an ordinary
     character, that character may be preceded by `\'.  This also
     applies to the character bounding the regular expression
     (often `/') and to `\' itself.

     To understand addressing in ed it is necessary to know that
     at any time there is a current line.  Generally speaking,
     the current line is the last line affected by a command;
     however, the exact effect on the current line is discussed
     under the description of the command.  Addresses are con-
     structed as follows.

        1. The character `.' addresses the current line.

        2. The character `$' addresses the last line of the
           buffer.

        3. A decimal number n addresses the n-th line of the
           buffer.

        4. `'x' addresses the line marked with the mark name
           character x, which must be a lower-case letter.  Lines
           are marked with the k command described below.

        5. A regular expression enclosed in slashes `/' addresses
           the first line found by searching toward the end of
           the buffer and stopping at the first line containing a
           string matching the regular expression.  If necessary
           the search wraps around to the beginning of the

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           buffer.

        6. A regular expression enclosed in queries `?' addresses
           the first line found by searching toward the beginning
           of the buffer and stopping at the first line contain-
           ing a string matching the regular expression.  If nec-
           essary the search wraps around to the end of the
           buffer.

        7. An address followed by a plus sign `+' or a minus sign
           `-' followed by a decimal number specifies that
           address plus (resp. minus) the indicated number of
           lines.  The plus sign may be omitted.

        8. If an address begins with `+' or `-' the addition or
           subtraction is taken with respect to the current line;
           e.g. `-5' is understood to mean `.-5'.

        9. If an address ends with `+' or `-', then 1 is added
           (resp. subtracted).  As a consequence of this rule and
           rule 8, the address `-' refers to the line before the
           current line.  Moreover, trailing `+' and `-' charac-
           ters have cumulative effect, so `--' refers to the
           current line less 2.

        10.To maintain compatibility with earlier version of the
           editor, the character `^' in addresses is entirely
           equivalent to `-'.

     Commands may require zero, one, or two addresses.  Commands
     which require no addresses regard the presence of an address
     as an error.  Commands which accept one or two addresses
     assume default addresses when insufficient are given.  If
     more addresses are given than such a command requires, the
     last one or two (depending on what is accepted) are used.

     Addresses are separated from each other typically by a comma
     `,'.  They may also be separated by a semicolon `;'.  In
     this case the current line `.' is set to the previous
     address before the next address is interpreted.  This fea-
     ture can be used to determine the starting line for forward
     and backward searches (`/', `?').  The second address of any
     two-address sequence must correspond to a line following the
     line corresponding to the first address.

     In the following list of ed commands, the default addresses
     are shown in parentheses.  The parentheses are not part of
     the address, but are used to show that the given addresses
     are the default.

     As mentioned, it is generally illegal for more than one com-
     mand to appear on a line.  However, any command may be suf-
     fixed by `p' or by `l', in which case the current line is
     either printed or listed respectively in the way discussed

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     below.

     ( . )a
     <text>
          The append command reads the given text and appends it
          after the addressed line.  `.' is left on the last line
          input, if there were any, otherwise at the addressed
          line.  Address `0' is legal for this command; text is
          placed at the beginning of the buffer.

     ( . , . )c
     <text>
          The change command deletes the addressed lines, then
          accepts input text which replaces these lines.  `.' is
          left at the last line input; if there were none, it is
          left at the first line not deleted.

     ( . , . ) d
          The delete command deletes the addressed lines from the
          buffer.  The line originally after the last line
          deleted becomes the current line; if the lines deleted
          were originally at the end, the new last line becomes
          the current line.

     e filename
          The edit command causes the entire contents of the
          buffer to be deleted, and then the named file to be
          read in.  `.' is set to the last line of the buffer.
          The number of characters read is typed.  `filename' is
          remembered for possible use as a default file name in a
          subsequent r or w command.

     f filename
          The filename command prints the currently remembered
          file name.  If `filename' is given, the currently
          remembered file name is changed to `filename'.

     (1,$)g/regular expression/command list
          In the global command, the first step is to mark every
          line which matches the given regular expression.  Then
          for every such line, the given command list is executed
          with `.' initially set to that line.  A single command
          or the first of multiple commands appears on the same
          line with the global command.  All lines of a multi-
          line list except the last line must be ended with `\'.
          A, i, and c commands and associated input are permit-
          ted; the `.' terminating input mode may be omitted if
          it would be on the last line of the command list.  The
          (global) commands, g, and v, are not permitted in the
          command list.

     ( . )i
     <text>
     This command inserts the given text before the addressed

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          line.  `.' is left at the last line input; if there
          were none, at the addressed line.  This command differs
          from the a command only in the placement of the text.

     ( . )kx
          The mark command marks the addressed line with name x,
          which must be a lower-case letter.  The address form
          `'x' then addresses this line.

     ( . , . )l
          The list command prints the addressed lines in an unam-
          biguous way: non-graphic characters are printed in
          octal, and long lines are folded.  An l command may
          follow any other on the same line.

     ( . , . )ma
          The move command repositions the addressed lines after
          the line addressed by a.  The last of the moved lines
          becomes the current line.

     ( . , . )p
          The print command prints the addressed lines.  `.'  is
          left at the last line printed.  The p command may be
          placed on the same line after any command.

     q
          The quit command causes ed to exit.  No automatic write
          of a file is done.

     ($)r filename
          The read command reads in the given file after the
          addressed line.  If no file name is given, the remem-
          bered file name, if any, is used (see e and f com-
          mands).  The remembered file name is not changed unless
          `filename' is the very first file name mentioned.
          Address `0' is legal for r and causes the file to be
          read at the beginning of the buffer.  If the read is
          successful, the number of characters read is typed.
          `.' is left at the last line read in from the file.

     ( . , . )s/regular expression/replacement/         or,
     ( . , . )s/regular expression/replacement/g
          The substitute command searches each addressed line for
          an occurrence of the specified regular expression.  On
          each line in which a match is found, all matched
          strings are replaced by the replacement specified, if
          the global replacement indicator `g' appears after the
          command.  If the global indicator does not appear, only
          the first occurrence of the matched string is replaced.
          It is an error for the substitution to fail on all
          addressed lines.  Any character other than space or
          new-line may be used instead of `/' to delimit the reg-
          ular expression and the replacement.  `.' is left at
          the last line substituted.

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          An ampersand `&' appearing in     the replacement is
          replaced by the string matching the regular expression.
          The special meaning of `&' in     this context may be sup-
          pressed by preceding it by `\'.  As a more general fea-
          ture, the characters `\n', where n is a digit, are
          replaced by the text matched by the n-th regular subex-
          pression enclosed between `\(' and `\)'.  When nested,
          parenthesized subexpressions are present, n is deter-
          mined by counting occurrences of `\(' starting from the
          left.

          Lines may be split by substituting new-line characters
          into them.  The new-line in the replacement string must
          be escaped by preceding it by `\'.

     ( . , . ) t a
          This command acts just like the m command, except that
          a copy of the addressed lines is placed after address a
          (which may be 0).  `.' is left on the last line of the
          copy.

     (1,$)v/regular expression/command list
          This command is the same as the global command except
          that the command list is executed with `.' initially
          set to every line except those matching the regular
          expression.

     (1,$)w filename
          The write command writes the addressed lines onto the
          given file.  If the file does not exist, it is created
          mode 666 (readable and writeable by everyone).  The
          remembered file name is not changed unless `filename'
          is the very first file name mentioned.  If no file name
          is given, the remembered file name, if any, is used
          (see e and f commands).  `.' is unchanged.  If the com-
          mand is successful, the number of characters written is
          typed.

     ($)=
          The line number of the addressed line is typed.  `.' is
          unchanged by this command.

     !UNIX command
          The remainder of the line after the `!' is sent to UNIX
          to be interpreted as a command.  `.' is unchanged.

     ( .+1 )<newline>
          An address alone on a line causes the addressed line to
          be printed.  A blank line alone is equivalent to
          `.+1p'; it is useful for stepping through text.

     If an interrupt signal (ASCII DEL) is sent, ed prints a `?'
     and returns to its command level.

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     Some size limitations: 512 characters per line, 256 charac-
     ters per global command list, 64 characters per file name,
     and 128K characters in the temporary file.  The limit on the
     number of lines depends on the amount of core: each line
     takes 1 word.

FILES
     /tmp/#, temporary; `#' is the process number (in octal).

DIAGNOSTICS
     `?' for errors in commands; `TMP' for temporary file over-
     flow.

SEE ALSO
     A Tutorial Introduction to the ED Text Editor (B. W. Ker-
     nighan)

BUGS
     The s command causes all marks to be lost on lines changed.

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