NAME
ed —
text editor
SYNOPSIS
ed |
[-]
[-Esx]
[-p
string]
[file] |
DESCRIPTION
ed is a line-oriented text editor. It is used to create,
display, modify, and otherwise manipulate text files. If invoked with a
file argument, then a copy of
file
is read into the editor's buffer. Changes are made to this copy and not
directly to
file itself. Upon quitting
ed, any changes not explicitly saved with a
w command are lost.
Editing is done in two distinct modes:
command and
input. When first invoked,
ed is in
command mode. In this mode, commands are read from the standard input and
executed to manipulate the contents of the editor buffer.
A typical command might look like:
which replaces all occurrences of the string
old with
new.
When an input command, such as
a (append),
i
(insert), or
c (change) is given,
ed
enters input mode. This is the primary means of adding text to a file. In this
mode, no commands are available; instead, the standard input is written
directly to the editor buffer. Lines consist of text up to and including a
newline character. Input mode is terminated by entering a single period
(‘
.
’) on a line.
All
ed commands operate on whole lines or ranges of lines;
e.g., the
d command deletes lines; the
m
command moves lines, and so on. It is possible to modify only a portion of a
line by means of replacement, as in the example above. However, even here, the
s command is applied to whole lines at a time.
In general,
ed commands consist of zero or more line
addresses, followed by a single character command and possibly additional
parameters; i.e., commands have the structure:
[address [,address]]command[parameters]
The address(es) indicate the line or range of lines to be affected by the
command. If fewer addresses are given than the command accepts, then default
addresses are supplied.
The options are as follows:
-
-
- -
- Same as the -s option (deprecated).
-
-
- -E
- Enables the use of extended regular expressions instead of
the basic regular expressions that are normally used.
-
-
- -p
string
- Specifies a command prompt. This may be toggled on and off
with the P command.
-
-
- -s
- Suppress diagnostics. This should be used if
ed standard input is from a script.
-
-
- -x
- Prompt for an encryption key to be used in subsequent reads
and writes (see the x command).
-
-
- file
- Specifies the name of a file to read. If
file is prefixed with a bang
(‘
!
’), then it is interpreted as a
shell command. In this case, what is read is the standard output of
file executed via
sh(1). To read a file whose name
begins with a bang, prefix the name with a backslash
(‘\
’). The default filename is set to
file only if it is not prefixed with a bang.
LINE ADDRESSING
An address represents the number of a line in the buffer.
ed
maintains a
current address which is typically supplied to
commands as the default address when none is specified. When a file is first
read, the current address is set to the last line of the file. In general, the
current address is set to the last line affected by a command.
A line address is constructed from one of the bases in the list below,
optionally followed by a numeric offset. The offset may include any
combination of digits, operators (i.e., ‘+’, ‘-’, and
‘^’), and whitespace. Addresses are read from left to right, and
their values are computed relative to the current address.
One exception to the rule that addresses represent line numbers is the address
0 (zero). This means “before the first line”,
and is legal wherever it makes sense.
An address range is two addresses separated either by a comma or semi-colon. The
value of the first address in a range cannot exceed the value of the second.
If only one address is given in a range, then the second address is set to the
given address. If an
n-tuple of
addresses is given where
n > 2, then the corresponding
range is determined by the last two addresses in the
n-tuple. If only one address is
expected, then the last address is used.
Each address in a comma-delimited range is interpreted relative to the current
address. In a semi-colon-delimited range, the first address is used to set the
current address, and the second address is interpreted relative to the first.
The following address symbols are recognized:
-
-
- .
- The current line (address) in the buffer.
-
-
- $
- The last line in the buffer.
-
-
- n
- The nth line in
the buffer where n is a number in the range
[0,$].
-
-
- -
or ^
- The previous line. This is equivalent to
-1 and may be repeated with cumulative effect.
-
-
- -n
or ^n
- The nth previous
line, where n is a non-negative number.
-
-
- +
- The next line. This is equivalent to +1
and may be repeated with cumulative effect.
-
-
- +n
- The nth next
line, where n is a non-negative number.
-
-
- whitespace
n
- whitespace followed by a number
n is interpreted as
‘+n’.
-
-
- ,
or %
- The first through last lines in the buffer. This is
equivalent to the address range 1,$.
-
-
- ;
- The current through last lines in the buffer. This is
equivalent to the address range .,$.
-
-
- /re/
- The next line containing the regular expression
re. The search wraps to the beginning of the buffer
and continues down to the current line, if necessary. //
repeats the last search.
-
-
- ?re?
- The previous line containing the regular expression
re. The search wraps to the end of the buffer and
continues up to the current line, if necessary. ??
repeats the last search.
-
-
- ´lc
- The line previously marked by a k (mark)
command, where lc is a lower case letter.
REGULAR EXPRESSIONS
Regular expressions are patterns used in selecting text. For example, the
ed command
prints all lines containing
string. Regular expressions are
also used by the
s command for selecting old text to be
replaced with new.
In addition to specifying string literals, regular expressions can represent
classes of strings. Strings thus represented are said to be matched by the
corresponding regular expression. If it is possible for a regular expression
to match several strings in a line, then the leftmost longest match is the one
selected.
The following symbols are used in constructing regular expressions:
-
-
- c
- Any character c not listed below,
including ‘{’, ‘}’, ‘(’,
‘)’, ‘<’, and ‘>’ matches
itself.
-
-
- \c
- Any backslash-escaped character c, except
for ‘{’, ‘}’, ‘(’, ‘)’,
‘<’, and ‘>’ matches itself.
-
-
- .
- Matches any single character.
-
-
- [char-class]
- Matches any single character in the character class
char-class. See
CHARACTER CLASSES below for
further information.
-
-
- [^char-class]
- Matches any single character, other than newline, not in
the character class char-class.
-
-
- ^
- If ^ is the first character of a regular
expression, then it anchors the regular expression to the beginning of a
line. Otherwise, it matches itself.
-
-
- $
- If $ is the last character of a regular
expression, it anchors the regular expression to the end of a line.
Otherwise, it matches itself.
-
-
- \<
- Anchors the single character regular expression or
subexpression immediately following it to the beginning of a word. (This
may not be available.)
-
-
- \>
- Anchors the single character regular expression or
subexpression immediately following it to the end of a word. (This may not
be available.)
-
-
- \(re\)
- Defines a subexpression re.
Subexpressions may be nested. A subsequent backreference of the form
\n, where n is a number in the range
[1,9], expands to the text matched by the
nth subexpression. For example,
the regular expression \(.*\)\1 matches any string
consisting of identical adjacent substrings. Subexpressions are ordered
relative to their left delimiter.
-
-
- *
- Matches the single character regular expression or
subexpression immediately preceding it zero or more times. If
* is the first character of a regular expression or
subexpression, then it matches itself. The * operator
sometimes yields unexpected results. For example, the regular expression
b* matches the beginning of the string
abbb (as opposed to the substring
bbb), since a null match is the only leftmost
match.
-
-
- \{n,m\} \{n,\} \{n\}
- Matches the single character regular expression or
subexpression immediately preceding it at least n and at
most m times. If m is omitted, then it
matches at least n times. If the comma is also omitted,
then it matches exactly n times.
Additional regular expression operators may be defined depending on the
particular
regex(3)
implementation.
CHARACTER CLASSES
A character class specifies a set of characters. It is written within square
brackets ([]) and in its most basic form contains just the characters in the
set.
To include a ‘]’ in a character class, it must be the first
character. A range of characters may be specified by separating the end
characters of the range with a ‘-’, e.g., ‘a-z’
specifies the lower case characters.
The following literals can also be used within character classes as shorthand
for particular sets of characters:
- [:alnum:]
- Alphanumeric characters.
- [:cntrl:]
- Control characters.
- [:lower:]
- Lowercase alphabetic characters.
- [:space:]
- Whitespace (space, tab, newline, form feed, etc.)
- [:alpha:]
- Alphabetic characters.
- [:digit:]
- Numeric characters (digits).
- [:print:]
- Printable characters.
- [:upper:]
- Uppercase alphabetic characters.
- [:blank:]
- Blank characters (space and tab).
- [:graph:]
- Graphical characters (printing nonblank characters).
- [:punct:]
- Punctuation characters.
- [:xdigit:]
- Hexadecimal digits.
If ‘-’ appears as the first or last character of a character class,
then it matches itself. All other characters in a character class match
themselves.
Patterns in a character class of the form
[.col-elm.] or
[=col-elm=] where
col-elm is a
collating element are interpreted according to
locale(5) (not currently
supported). See
regex(3) for an
explanation of these constructs.
COMMANDS
All
ed commands are single characters, though some require
additional parameters. If a command's parameters extend over several lines,
then each line except for the last must be terminated with a backslash
(‘
\
’).
In general, at most one command is allowed per line. However, most commands
accept a print suffix, which is any of
p (print),
l (list), or
n (enumerate), to print the
last line affected by the command.
An interrupt (typically ^C) has the effect of aborting the current command and
returning the editor to command mode.
ed recognizes the following commands. The commands are shown
together with the default address or address range supplied if none is
specified (in parentheses), and other possible arguments on the right.
-
-
- (.)a
- Appends text to the buffer after the addressed line. Text
is entered in input mode. The current address is set to last line
entered.
-
-
- (.,.)c
- Changes lines in the buffer. The addressed lines are
deleted from the buffer, and text is appended in their place. Text is
entered in input mode. The current address is set to last line
entered.
-
-
- (.,.)d
- Deletes the addressed lines from the buffer. If there is a
line after the deleted range, then the current address is set to this
line. Otherwise the current address is set to the line before the deleted
range.
-
-
- e
file
- Edits file, and sets the default
filename. If file is not specified, then the default
filename is used. Any lines in the buffer are deleted before the new file
is read. The current address is set to the last line read.
-
-
- e
!command
- Edits the standard output of command,
(see ! command below). The default
filename is unchanged. Any lines in the buffer are deleted before the
output of command is read. The current address is set to
the last line read.
-
-
- E
file
- Edits file unconditionally. This is
similar to the e command, except that unwritten changes
are discarded without warning. The current address is set to the last line
read.
-
-
- f
file
- Sets the default filename to file. If
file is not specified, then the default unescaped
filename is printed.
-
-
- (1,$)g/re/command-list
- Applies command-list to each of the
addressed lines matching a regular expression re.
The current address is set to the line currently matched before
command-list is executed. At the end of the
g command, the current address is set to the last line
affected by command-list.
Each command in command-list must be on a separate
line, and every line except for the last must be terminated by a backslash
(‘\’). Any commands are allowed, except for
g, G, v, and
V. A newline alone in command-list
is equivalent to a p command.
-
-
- (1,$)G/re/
- Interactively edits the addressed lines matching a regular
expression re. For each matching line, the line is
printed, the current address is set, and the user is prompted to enter a
command-list. At the end of the G
command, the current address is set to the last line affected by (the
last) command-list.
The format of command-list is the same as that of the
g command. A newline alone acts as a null command list.
A single ‘&’ repeats the last non-null command list.
-
-
- H
- Toggles the printing of error explanations. By default,
explanations are not printed. It is recommended that ed
scripts begin with this command to aid in debugging.
-
-
- h
- Prints an explanation of the last error.
-
-
- (.)i
- Inserts text in the buffer before the current line. Text is
entered in input mode. The current address is set to the last line
entered.
-
-
- (.,.+1)j
- Joins the addressed lines. The addressed lines are deleted
from the buffer and replaced by a single line containing their joined
text. The current address is set to the resultant line.
-
-
- (.)klc
- Marks a line with a lower case letter
lc. The line can then be addressed as
'lc (i.e., a single quote followed by
lc) in subsequent commands. The mark is not cleared
until the line is deleted or otherwise modified.
-
-
- (.,.)l
- Prints the addressed lines unambiguously. If a single line
fills more than one screen (as might be the case when viewing a binary
file, for instance), a “--More--” prompt is printed on the
last line. ed waits until the RETURN key is pressed
before displaying the next screen. The current address is set to the last
line printed.
-
-
- (.,.)m(.)
- Moves lines in the buffer. The addressed lines are moved to
after the right-hand destination address, which may be the address
0 (zero). The current address is set to the last line
moved.
-
-
- (.,.)n
- Prints the addressed lines along with their line numbers.
The current address is set to the last line printed.
-
-
- (.,.)p
- Prints the addressed lines. The current address is set to
the last line printed.
-
-
- P
- Toggles the command prompt on and off. Unless a prompt was
specified with the command-line option -p
string, the command prompt is by default turned
off.
-
-
- q
- Quits ed.
-
-
- Q
- Quits ed unconditionally. This is similar
to the q command, except that unwritten changes are
discarded without warning.
-
-
- ($)r
file
- Reads file to after the addressed
line. If file is not specified, then the default
filename is used. If there was no default filename prior to the command,
then the default filename is set to file. Otherwise,
the default filename is unchanged. The current address is set to the last
line read.
-
-
- ($)r
!command
- Reads to after the addressed line the standard output of
command, (see the ! command
below). The default filename is unchanged. The current address is set to
the last line read.
-
-
- (.,.)s/re/replacement/, (.,.)s/re/replacement/g, (.,.)s/re/replacement/n
- Replaces text in the addressed lines matching a regular
expression re with
replacement. By default, only the first match in
each line is replaced. If the g (global) suffix is
given, then every match to be replaced. The n suffix,
where n is a positive number, causes only the
nth match to be replaced. It is
an error if no substitutions are performed on any of the addressed lines.
The current address is set the last line affected.
re and replacement may be
delimited by any character other than space and newline (see the
s command below). If one or two of the last delimiters
is omitted, then the last line affected is printed as though the print
suffix p were specified.
An unescaped ‘
&
’ in
replacement is replaced by the currently matched
text. The character sequence \m, where
m is a number in the range [1,9], is replaced by the
mth backreference expression of
the matched text. If replacement consists of a
single ‘%
’, then
replacement from the last substitution is used.
Newlines may be embedded in replacement if they are
escaped with a backslash (‘\
’).
-
-
- (.,.)s
- Repeats the last substitution. This form of the
s command accepts a count suffix n, or
any combination of the characters r,
g, and p. If a count suffix
n is given, then only the
nth match is replaced. The
r suffix causes the regular expression of the last
search to be used instead of that of the last substitution. The
g suffix toggles the global suffix of the last
substitution. The p suffix toggles the print suffix of
the last substitution. The current address is set to the last line
affected.
-
-
- (.,.)t(.)
- Copies (i.e., transfers) the addressed lines to after the
right-hand destination address, which may be the address
0 (zero). The current address is set to the last line
copied.
-
-
- u
- Undoes the last command and restores the current address to
what it was before the command. The global commands g,
G, v, and V are
treated as a single command by undo. u is its own
inverse.
-
-
- (1,$)v/re/command-list
- Applies command-list to each of the
addressed lines not matching a regular expression
re. This is similar to the g
command.
-
-
- (1,$)V/re/
- Interactively edits the addressed lines not matching a
regular expression re. This is similar to the
G command.
-
-
- (1,$)w
file
- Writes the addressed lines to file.
Any previous contents of file are lost without
warning. If there is no default filename, then the default filename is set
to file, otherwise it is unchanged. If no filename
is specified, then the default filename is used. The current address is
unchanged.
-
-
- (1,$)wq
file
- Writes the addressed lines to file,
and then executes a q command.
-
-
- (1,$)w
!command
- Writes the addressed lines to the standard input of
command, (see the ! command
below). The default filename and current address are unchanged.
-
-
- (1,$)W
file
- Appends the addressed lines to the end of
file. This is similar to the w
command, except that the previous contents of file are not clobbered. The
current address is unchanged.
-
-
- x
- Prompts for an encryption key which is used in subsequent
reads and writes. If a newline alone is entered as the key, then
encryption is turned off. Otherwise, echoing is disabled while a key is
read. Encryption/decryption is done using the
bdes(1) algorithm.
-
-
- (.+1)zn
- Scrolls n lines at a time starting at
addressed line. If n is not specified, then the
current window size is used. The current address is set to the last line
printed.
-
-
- ($)=
- Prints the line number of the addressed line.
-
-
- (.+1)newline
- Prints the addressed line, and sets the current address to
that line.
-
-
- !command
- Executes command via
sh(1). If the first character of
command is !, then it is replaced
by text of the previous !command. ed
does not process command for ‘\’
(backslash) escapes. However, an unescaped ‘%’ is replaced by
the default filename. When the shell returns from execution, a
‘!’ is printed to the standard output. The current line is
unchanged.
LIMITATIONS
ed processes
file arguments for backslash
escapes, i.e., in a filename, any characters preceded by a backslash
(‘
\
’) are interpreted literally.
If a text (non-binary) file is not terminated by a newline character, then
ed appends one on reading/writing it. In the case of a
binary file,
ed does not append a newline on
reading/writing.
ENVIRONMENT
-
-
TMPDIR
- The location used to store temporary files.
FILES
- /tmp/ed.*
- buffer file
- ed.hup
- where ed attempts to write the buffer if
the terminal hangs up
DIAGNOSTICS
When an error occurs,
ed prints a “?” and either
returns to command mode or exits if its input is from a script. An explanation
of the last error can be printed with the
h (help) command.
Since the
g (global) command masks any errors from failed
searches and substitutions, it can be used to perform conditional operations
in scripts; e.g.,
replaces any occurrences of
old with
new.
If the
u (undo) command occurs in a global command list, then
the command list is executed only once.
If diagnostics are not disabled, attempting to quit
ed or edit
another file before writing a modified buffer results in an error. If the
command is entered a second time, it succeeds, but any changes to the buffer
are lost.
SEE ALSO
bdes(1),
sed(1),
sh(1),
vi(1),
regex(3)
USD:09-10
B. W. Kernighan and
P. J. Plauger, Software Tools in
Pascal, Addison-Wesley,
1981.
HISTORY
An
ed command appeared in
Version 1
AT&T UNIX.