11/3/71                                                    ED (I)

NAME            ed  --  editor

SYNOPSIS        ed [ name ]

DESCRIPTION     ed is the standard text editor.  ed is based on

                QED [reference] but is fully if succinctly de-

                scribed here.  Differences between ed and QED are

                also noted to simplify the transition to the less

                powerful editor.

                If the optional argument is given, ed simulates

                an e command on the named file; that is to say,

                the file is read into ed's buffer so that it can

                be edited.

                ed operates on a copy of any file it is editing;

                changes made in the copy have no effect on the

                file until an explicit write (w) 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 struc-

                ture: zero or more addresses followed by a single

                character command, possibly followed by parame-

                ters 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 commands

                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 is an expression

                which specifies a set of strings of characters.

                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 fol-


                   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 reg-

                      ular expression matches the null character

                      at the beginning of a line.

                   3. A currency symbol ($) at the end of a regu-

                      lar expression matches the null character

                      at the end of a line.

                   4. A period (.) matches any character but a

                      new-line character.

                   5. A regular expression followed by an aster-

                      isk (*) matches any number of adjacent oc-

                      currences (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 but new-line and the characters

                      in the string.

                   7. The concatenation of regular expressions is

                      a regular expression which matches the con-

                      catenation of the strings matched by the

                      components of the regular expression.

                   8. The null regular expression standing alone

                      is equivalent to the last regular expres-

                      sion encountered.

                Regular expressions are used in addresses to

                specify lines and in one command (s, see below)

                to specify a portion of a line which is to be re-


                If it is desired to use one of the regular ex-

                pression metacharacters as an ordinary character,

                that character may be preceded by "\".  This also

                applies to the character bounding the regular ex-

                pression (often "/") and to "\" itself.

                Addresses are constructed as follows.  To under-

                stand addressing in ed it is necessary to know

                that at any time there is a current line.  Gener-

                ally speaking, the current line is the last line

                affected by a command; however, the exact effect

                on the current line by each command is discussed

                under the description of the command.

                   1. The character "." addresses the current


                   2. The character "$" addresses the last line

                      of the buffer.

                   3. A decimal number n addresses the nth line

                      of the buffer.

                   4. 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.

                   5. 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 found

                      containing a string matching the regular

                      expression.  If necessary 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.

                Commands may require zero, one, or two addresses.

                Commands which require no addresses regard the

                presence of an address as an error.  Commands

                which require the presence of one address all as-

                sume a default address (often ".")  but if given

                more than one address ignore any extra and use

                the last given.  Commands which require two ad-

                dresses have defaults in the case of zero or one

                address but use the last two if more than two are


                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 the previous address before the

                next address is interpreted.  This feature is

                used to control the starting line for forward and

                backward searches ("/", "?").

                In the following list of ed commands, the default

                addresses are shown in parentheses.  The paren-

                theses 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 command to appear on a line.  However,

                any command may be suffixed by "p" (for "print").

                In that case, the current line is printed after

                the command is complete.

                In any two-address command, it is illegal for the

                first address to lie after the second address.




                      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.

                      (NOTE: the default address differs from

                      that of QED.)




                      The change command deletes the addressed

                      lines, then accepts input text which re-

                      places these lines.  "." is left at the

                      last line input; if there were none, it is

                      left at the first line not changed.


                      The delete command deletes the addressed

                      lines from the buffer.  "." is left at the

                      first line not deleted

                   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.

                   (1,$)g/regular expression/command

                      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 is executed with

                      "." set to that line.  The repeated command

                      cannot be a, q, i, or c.




                      This command inserts the given text before

                      the addressed 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



                      The list command prints the addressed lines

                      in an unambiguous way.  Non-printing char-

                      acters are over-struck as follows:

                         char  prints

                          bs     \

                         tab     >

                         ret     <

                         SI      I

                         SO      O

                      All character preceded by a prefix (ESC)

                      character are printed over-struck with ^

                      without the prefix.  Long lines are folded

                      with the sequence \newline.


                      The print command prints the addressed

                      lines.  "."  is left at the last line



                      The quit command causes ed to exit.  No au-

                      tomatic 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 file last mentioned in e, r,

                      or w commands is read.  Address "0" is le-

                      gal 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/

                      The substitute command searches each ad-

                      dressed line for an occurrence of the spec-

                      ified regular expression.  On each line in

                      which a match is found, the first (and only

                      first, compare QED) matched string is re-

                      placed by the replacement specified, 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 regular expression

                      and the replacement.  "." is left at the

                      last line substituted.

                      The ampersand "&" appearing in the replace-

                      ment is replaced by the regular expression

                      that was matched.  The special meaning of

                      "&" in this context may be suppressed by

                      preceding it by "\".

                   (1,$)w filename

                      The write command writes the addressed

                      lines onto the given file.  If no file name

                      is given, the file last named in e, r, or w

                      commands is written.  "." 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 com-

                      mand.  "." is unchanged.


                      A blank line alone is equivalent to ".+1p";

                      it is useful for stepping through text.

                Ed can edit at most 1500 lines and the maximum

                size of a line is 256 characters.  The differ-

                ences between ed and QED are:

                   1. There is no "\f" character; input mode is

                      left by typing "." alone on a line.

                   2. There is only one buffer and hence no "\b"

                      stream directive.

                   3.  The commands are limited to:

                          a c d e g i l p q r s w = !

                      where e is new.

                   4. The only special characters in regular ex-

                      pressions are:

                          *  ^  $  [  .

                      which have the usual meanings.  However,

                      "^" and "$" are only effective if they are

                      the first or last character respectively of

                      the regular expression.  Otherwise suppres-

                      sion of special meaning is done by preced-

                      ing the character by "\", which is not oth-

                      erwise special.

                   5. In the substitute command, only the left-

                      most occurrence of the matched regular ex-

                      pression is substituted.

                   7. The a command has a different default ad-


FILES           /tmp/etma, etmb, ... temporary

                /etc/msh is used to implement the "!" command.

SEE ALSO        --

DIAGNOSTICS     "?" for any error

BUGS            ed is used as the shell for the editing system.

                it has the editing system UID built in and if in-

                voked under this UID will give slightly different

                responses.  This is a little kludgy.

OWNER           ken