ed - text editor

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:

An ordinary character (not one of those discussed below) is a regular expression and matches that character.

A circumflex `^' at the beginning of a regular expression matches the empty string at the beginning of a line.

A currency symbol `$' at the end of a regular expression matches the null character at the end of a line.

A period `.' matches any character except a new-line character.

A regular expression followed by an asterisk `*' matches any number of adjacent occurrences (including zero)\| of the regular expression it follows.

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.

The concatenation of regular expressions is a regular expression which matches the concatenation of the strings matched by the components of the regular expression.

A regular expression enclosed between the sequences `$' and `$'is identical to the unadorned expression; the construction has side effects discussed under the s command.

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.

The character `.' addresses the current line.

The character `$' addresses the last line of the buffer.

A decimal number n addresses the n-th line of the buffer.

`'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.

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.

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.

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.

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'.

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.

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 )
	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.

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