    ED(I)                        1/15/73                        ED(I)

    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 on-
         ly 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 address-
         es 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.

         5. A regular expression followed by an asterisk `*'  matches

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            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 ex-
            cept new-line and the characters in the string.

         7. The concatenation of regular expressions is a regular ex-
            pression  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
               buffer.

            6. A regular expression enclosed in queries `?' addresses

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               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  ad-
               dress  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 as-
         sume 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  ad-
         dress  before the next address is interpreted.  This feature
         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
         below.

         ( . )a
         <text>
         .

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              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 delet-
              ed  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 re-
              membered 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 ad-
              dressed 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.

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         ( . )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  oc-
              tal,  and long lines are folded.  An l command may fol-
              low 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 ad-
              dressed line.  If no file name is given, the remembered
              file name, if any, is used (see e and f commands).  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  be-
              ginning  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  ad-
              dressed  lines.  Any character other than space or new-
              line may be used instead of `/' to delimit the  regular
              expression  and  the  replacement.   `.' is left at the
              last line substituted.

              An ampersand `&' appearing in the  replacement  is  re-
              placed  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  re-

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              placed  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 ex-
              pression.

         (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 re-
              membered 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 command 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.

         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.

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    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.
         Kernighan)

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

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