ED(1)

NAME
ed - text editor

SYNOPSIS
ed [ - ] [ -p[prompt] ] [ -u ] [ -x ] [ 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. If -p is present, ed prompts for commands with `* ' (or prompt if given.) If -u is present, all lower case text in the buffer is converted to upper case. If -x is present, an x command is simulated first to handle an encrypted file. The optional - suppresses the printing of explanatory output and should be used when the standard input is an editor script.

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.

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. Missing addresses are supplied by default.

In general, only one command may appear on a line. Certain commands allow the addition of text to 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. In the following specification for regular expressions the word `character' means any character but newline.

1.  Any character except a special character matches itself. Special characters are the regular expression delimiter plus \[. and sometimes ^*$.

2.  A . matches any character.

3.  A \ followed by any character except a digit or () matches that character.

4.  A nonempty string s bracketed [s] (or [^s]) matches any character in (or not in) s. In s, \ has no special meaning, and ] may only appear as the first letter. A substring a-b, with a and b in ascending ASCII order, stands for the inclusive range of ASCII characters.

5.  A regular expression of form 1-4 followed by * matches a sequence of 0 or more matches of the regular expression.

6.  A regular expression, x, of form 1-8, bracketed \(x\) matches what x matches.

7.  A \ followed by a digit n matches a copy of the string that the bracketed regular expression beginning with the nth \( matched.

8.  A regular expression of form 1-8, x, followed by a regular expression of form 1-7, y matches a match for x followed by a match for y, with the x match being as long as possible while still permitting a y match.

9.  A regular expression of form 1-8 preceded by ^ (or followed by $), is constrained to matches that begin at the left (or end at the right) end of a line.

10. A regular expression of form 1-9 picks out the longest among the leftmost matches in a line.

11. An empty regular expression stands for a copy of 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 name 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 line found by searching forward from the current line and stopping at the first line containing a string that matches the regular expression. If necessary the search wraps around to the beginning of the buffer.

6.  A regular expression enclosed in queries `?' addresses the line found by searching backward from the current line and stopping at the first line containing a string that matches 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 versions of the editor, the character `^' in addresses is 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. The special form `%' is an abbreviation for the address pair `1,$'.

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, most commands 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. Commands may also be suffixed by `n', meaning the output of the command is to be line numbered. These suffixes may be combined in any order.

(.)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 line preceding the deleted lines.

(., .)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. If `filename' is missing, the remembered name is used.

E filename
    This command is the same as e, except that no diagnostic results when no w has been given since the last buffer alteration.

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 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, or, if there were none, at the line before the addressed line. This command differs from the a command only in the placement of the text.

(., .+1)j
    This command joins the addressed lines into a single line; intermediate newlines simply disappear. `.' is left at the resulting line.

( . )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 two-digit octal, and long lines are folded. The l command may be placed on the same line after any non-i/o command.

(., .)ma
    The move command repositions the addressed lines after the line addressed by a. The last of the moved lines becomes the current line.

(., .)n
    The number command prints the addressed lines with line numbers and a tab at the left.

(., .)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 non-i/o command.

(., .)P
    This command is a synonym for p.

q   The quit command causes ed to exit. No automatic write of a file is done.

Q   This command is the same as q, except that no diagnostic results when no w has been given since the last buffer alteration.

($)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 file name is remembered if there was no remembered file name already. 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 punctuation character 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 `\'. 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 `\'.

    One or two trailing delimiters may be omitted, implying the `p' suffix. The special form `s' followed by no delimiters repeats the most recent substitute command on the addressed lines. The `s' may be followed by the letters r (use the most recent regular expression for the left hand side, instead of the most recent left hand side of a substitute command), p (complement the setting of the p suffix from the previous substitution), or g (complement the setting of the g suffix). These letters may be combined in any order.

(., .)ta
    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.

(., .)u
    The undo command restores the buffer to it's state before the most recent buffer modifying command. The current line is also restored. Buffer modifying commands are a, c, d, g, i, k, m, r, s, t, and v. For purposes of undo, g and v are considered to be a single buffer modifying command. Undo is its own inverse.

    When ed runs out of memory (at about 8000 lines on any 16 bit mini-computer such as the PDP-11) This full undo is not possible, and u can only undo the effect of the most recent substitute on the current line. This restricted undo also applies to editor scripts when ed is invoked with the - option.

(1, $)v/regular expression/command list
    This command is the same as the global command g except that the command list is executed g 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. The file name is remembered if there was no remembered file name already. 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 printed.

(1, $)W filename
    This command is the same as w, except that the addressed lines are appended to the file.

(1, $)wq filename
    This command is the same as w except that afterwards a q command is done, exiting the editor after the file is written.

x   A key string is demanded from the standard input. Later r, e and w commands will encrypt and decrypt the text with this key by the algorithm of crypt(1). An explicitly empty key turns off encryption. (.+1)zor,

(.+1)zn
    This command scrolls through the buffer starting at the addressed line. 22 (or n, if given) lines are printed. The last line printed becomes the current line. The value n is sticky, in that it becomes the default for future z commands.

($)=
    The line number of the addressed line is typed. `.' is unchanged by this command.

!<shell command>
    The remainder of the line after the `!' is sent to sh(1) to be interpreted as a command. `.' is unchanged.

(.+1,.+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 two addresses are present with no intervening semicolon, ed prints the range of lines. If they are separated by a semicolon, the second line is printed.

If an interrupt signal (ASCII DEL) is sent, ed prints `?interrupted' 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, on mini computers, 128K characters in the temporary file. The limit on the number of lines depends on the amount of core: each line takes 2 words.

When reading a file, ed discards ASCII NUL characters and all characters after the last newline. It refuses to read files containing non-ASCII characters.

FILES
/tmp/e*
edhup: work is saved here if terminal hangs up

SEE ALSO
B. W. Kernighan, A Tutorial Introduction to the ED Text Editor
B. W. Kernighan, Advanced editing on UNIX
sed(1), crypt(1)

DIAGNOSTICS
`?name' for inaccessible file; `?self-explanitory message' for other errors.

To protect against throwing away valuable work, a q or e command is considered to be in error, unless a w has occurred since the last buffer change. A second q or e will be obeyed regardless.

BUGS
The l command mishandles DEL.
The undo command causes marks to be lost on affected lines.
The x command, -x option, and special treatment of hangups only work on UNIX.