ED(1) | General Commands Manual | ED(1) |
ed
, red
—
text editor
ed |
[- ] [-s ]
[-p string]
[file] |
red |
[- ] [-s ]
[-p string]
[file] |
The ed
utility is a line-oriented text
editor. It is used to create, display, modify and otherwise manipulate text
files. When invoked as red
, the editor runs in
"restricted" mode, in which the only difference is that the editor
restricts the use of filenames which start with
‘!
’ (interpreted as shell commands by
ed
) or contain a
‘/
’. Note that editing outside of the
current directory is only prohibited if the user does not have write access
to the current directory. If a user has write access to the current
directory, then symbolic links can be created in the current directory, in
which case red
will not stop the user from editing
the file that the symbolic link points to.
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:
,s
/old/new/g
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 following options are available:
-s
ed
's
standard input is from a script.-p
stringAn address represents the number of a line in the buffer. The
ed
utility 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:
Regular expressions are patterns used in selecting text. For example, the command:
g
/string/
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 a 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 left-most longest match is the one selected.
The following symbols are used in constructing regular expressions:
{
’,
‘}
’,
‘(
’,
‘)
’,
‘<
’ and
‘>
’, matches itself.{
’,
‘}
’,
‘(
’,
‘)
’,
‘<
’ and
‘>
’, matches itself.]
’ in char-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 literal expressions can also be used in
char-class to specify sets of characters:
[:alnum:] | [:cntrl:] | [:lower:] | [:space:] |
[:alpha:] | [:digit:] | [:print:] | [:upper:] |
[:blank:] | [:graph:] | [:punct:] | [:xdigit:] |
If ‘-
’ appears as the
first or last character of char-class, then it matches
itself. All other characters in char-class match
themselves.
Patterns in char-class of the form:
where col-elm is a collating element are interpreted according to the current locale settings (not currently supported). See regex(3) and re_format(7) for an explanation of these constructs.
\(.*\)\1
’
matches any string consisting of identical adjacent substrings.
Subexpressions are ordered relative to their left delimiter.b*
’ matches the beginning of the
string ‘abbb
’ (as opposed to the
substring ‘bbb
’), since a null match
is the only left-most match.Additional regular expression operators may be defined depending on the particular regex(3) implementation.
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.
The ed
utility recognizes the following
commands. The commands are shown together with the default address or
address range supplied if none is specified (in parenthesis).
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.
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.
--More--
” prompt is
printed on the last line. The ed
utility waits
until the RETURN key is pressed before displaying the next screen. The
current address is set to the last line printed.-p
string, the command prompt is by default turned
off.ed
.ed
unconditionally. This is similar to the
q command, except that unwritten changes are discarded
without warning.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
m th 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 (\).
!
’, then it is replaced by text of
the previous !command. The
ed
utility 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.ed
attempts to write the buffer
if the terminal hangs upWhen 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.,
g
/old/s
//new/
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.
sed(1), sh(1), vi(1), regex(3), compat(5)
USD:12-13
B. W. Kernighan and P. J. Plauger, Software Tools in Pascal, 1981, Addison-Wesley.
B. W. Kernighan, A Tutorial Introduction to the UNIX Text Editor.
B. W. Kernighan, Advanced Editing on UNIX.
The ed
utility 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.
per line overhead: 4 ints
An ed
command appeared in
Version 1 AT&T UNIX.
The ed
utility does not recognize
multibyte characters.
April 9, 2021 | macOS 14.6 |