(I) NAME ed -- editor

SYNOPSIS ed [ name ]

DESCRIPTION
ed
is the standard text editor. ed is based on QED but is fully if succinctly described 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 structure: zero or more addresses followed by a single character command, possibly 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 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 follows:

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 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. Addresses are constructed as follows.

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 by each command is discussed under the description of the command.

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 assume a default address (often ".") but if given more than one address ignore any extras and use the last given. Commands which require two addresses have defaults in the case of zero or one address but use the last two if more than two are given.

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 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 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.

(.)a .
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.)


(.,.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 changed.

(.,.)d
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,s)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, g, i, or c.

(.)i .
This command inserts 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 text.

(.,.)l
The list command prints the addressed lines in an unambiguous way. Non-printing characters are over-struck as follows:

        char prints
        bs   [overstruct - \]
        tab   [overstruct - >]
        ret   [overstruct - <]
        SI    [overstruct I -]
        SO    [overstruct O -]
All characters preceded by a prefix (ESC) character are printed over-struck with without the prefix. Long lines are folded with the sequence \newline.

(.,.p)
The print command prints the addressed lines. "." is left at the last line printed.

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 file last mentioned in e, r, or w commands is read. 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 atthe last line of the file.

(.,.)s/regular expression/replacement/
The substitute command searches each addressed line for an occurence of the specified regular expression. On each line in which a match is found, the first (and only first, compare QED) matched string is replaced 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 delimitthe regular expression and the replacement. "." is left at the last line substituted. The ampersand "&" appearing in the replacement 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.

($)=
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.

(newline>
A blank line alone is equivalent to ".+lp"; 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 differences 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 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 expressions 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 suppression of special meaning is done by preceding the character by "\" , which is not otherwise special.
  5. In the substitute command, only the leftmost occurrence of the matched regular expression is substituted.
  6. The "a" command has a different default address.

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 systemUID built in and if invoked under this UID will give slightly different responses. This is a little kludgy.

OWNER ken

END OF ORIGINAL MANPAGE....1998 cLIeNUX commentary
ken is Ken Thompson. Thompson got a software patent on an on-the-fly regular expression compiler in QED. Thompson also happens to be the primary author of UNIX. The HTML formatting of this document may not be quite faithful to the original roff format manpage. In 1971 UNIX was a registered trademark of AT&T. I believe UNIX(tm) is now in the hands of The Open Group. Profuse thanks to Dennis Ritchie ( dmr in other legacy manpages in cLIeNUX, and the R in "K&R C") for putting this seminal document on his personal webpage.

here's some ed examples.