(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:
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.
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:
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.