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
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 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:
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
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
circumflex `^' 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
command.
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
constructed 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 the first line found by searching toward the
beginning of the buffer and stopping at the first line
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.
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 `-'
characters 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
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
command to appear on a line. However, any command may be
suffixed by `p' or by `l', in which case the current line is
either printed or listed respectively in the way discussed
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
permitted; 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 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
unambiguous 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
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 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
regular expression and the replacement. `.' is left at
the last line substituted.
An ampersand `&' appearing in the replacement is
replaced by the string matching the regular expression.
The special meaning of `&' in this context may be
suppressed by preceding it by `\'. As a more general
feature, the characters `\n', where n is a digit, are
replaced by the text matched by the n-th regular
subexpression enclosed between `\(' and `\)'. When
nested, parenthesized subexpressions are present, n is
determined 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
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
characters 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
overflow.
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.