ed(C)

Syntax

red [ - | -s ] [ -p string ]

Description

ed is the standard text editor. If the file 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. ed operates on a copy of the file it is editing; changes made to 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.

red is a restricted version of ed. It will only allow editing of files in the current directory. It prohibits executing sh(C) commands via the ! command. red displays an error message on any attempt to bypass these restrictions.

In general, red does not allow commands like !date or !sh.

Furthermore, red will not allow pathnames in its command line. For example, the command red /etc/passwd causes an error when the current directory is not /etc.

The options to ed are:

-s
-

Suppresses the printing of character counts by the e, r, and w commands, of diagnostics from e and q commands, and the ``!'' prompt after a ! shell command.

-p string

Allows the user to specify a prompt string.

Commands to ed have a simple and regular structure: zero, one, or two addresses followed by a single-character command, possibly followed by parameters to that command. These addresses specify one or more lines in the buffer. Every command that requires addresses has default addresses, so that the addresses can very 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 entering a period (.) alone at the beginning of a line.

ed supports a limited form of regular expression notation; regular expressions are used in addresses to specify lines and in some commands (for example, s) to specify portions of a line that are to be substituted. A regular expression specifies a set of character strings. A member of this set of strings is said to be matched by the regular expression. The regular expressions allowed by ed are constructed in accordance with the guidelines detailed in regexp(M).

To understand addressing in ed, it is necessary to know that there is a current line at all times. Generally speaking, the current line is the last line affected by a command; the exact effect on the current line is discussed under the description of each 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 lowercase letter. Lines are marked with the k command described below.
   

5. A regular expression enclosed by slashes (/) addresses the first line found by searching forward from the line following the current line 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 and continues up to and including the current line, so that the entire buffer is searched.

6. A regular expression enclosed in question marks (?) addresses the first line found by searching backward from the line preceding the current line 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 and continues up to and including the current line. See also the last paragraph before ``Files'' below.

7. An address followed by a plus sign (+) or a minus sign (-) followed by a decimal number specifies that address plus or 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; for example, -5 is understood to mean .-5.
   

9. If an address ends with ``+'' or ``-'', then 1 is added to or subtracted from the address, respectively. As a consequence of this rule and of rule 8 immediately above, the address ``-'' refers to the line preceding the current line. (To maintain compatibility with earlier versions of the editor, the character ``^'' in addresses is entirely equivalent to ``-''.) Moreover, trailing ``+'' and ``-'' characters have a cumulative effect, so ``--'' refers to the current line less 2.

10. For convenience, a comma (,) stands for the address pair 1, $, while a semicolon (;) stands for the pair . , $.

Typically, addresses are separated from each other by a comma. They may also be separated by a semicolon. In the latter case, the current line (.) is set to the first address, and only then is the second address calculated. This feature can be used to determine the starting line for forward and backward searches (see rules 5 and 6 above). The second address of any two-address sequence must correspond to a line that follows, in the buffer, 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.

It is generally illegal for more than one command to appear on a line. However, any command (except e, f, r, or w) may be suffixed by p or by l, in which case the current line is either printed or listed, respectively, as discussed below under the p and l commands.

(.)a
text
.

The append command reads the given text and appends it after the addressed line; dot is left at the address of the last inserted line, or, if there were no inserted lines, at the addressed line. Address 0 is legal for this command: it causes the appended text to be placed at the beginning of the buffer.

(.,.)c
text
.

The change command deletes the addressed lines, then accepts input text that replaces these lines; dot is left at the address of the last line input, or, if there were none, at the first line that was not deleted.

(.,.)d

The delete command deletes the addressed lines from the buffer. The line after the last line deleted becomes the current line; if the lines deleted were originally at the end of the buffer, the new last line becomes the current line.

e [ file ]

The edit command causes the entire contents of the buffer to be deleted, and then the named file to be read in; dot is set to the last line of the buffer. If no filename is given, the currently remembered filename, if any, is used (see the f command). The number of characters read is typed. file is remembered for possible use as a default filename in subsequent e, r, and w commands. If file begins with an exclamation (!), the rest of the line is taken to be a shell command. The output of this command is read for the e and r commands. For the w command, the file is used as the standard input for the specified command. Such a shell command is not remembered as the current filename.

E [ file ]

The Edit command is like e, except the editor does not check to see if any changes have been made to the buffer since the last w command.

f [ file ]

If file is given, the filename command changes the currently remembered filename to file; otherwise, it prints the currently remembered filename.

(1,$)g/regular-expression/command list

In the global command, the first step is to mark every line that 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 a list of commands appears on the same line as the global command. All lines of a multiline list except the last line must be ended with a ``\''; a, i, and c commands and associated input are permitted; the ``.'' terminating input mode may be omitted if it would be the last line of the command list. An empty command list is equivalent to the p command. The g, G, v, and V commands are not permitted in the command list. See also ``Limitations'' and the last paragraph before ``Files'' below.

(1,$)G/regular-expression/

In the interactive Global command, the first step is to mark every line that matches the given regular expression. Then, for every such line, that line is printed, dot (.) is changed to that line, and any one command (other than one of the a, c, i, g, G, v, and V commands) may be input and is executed. After the execution of that command, the next marked line is printed, and so on. A newline acts as a null command. An ampersand (&) causes the re-execution of the most recent command executed within the current invocation of G. Note that the commands input as part of the execution of the G command may address and affect any lines in the buffer. The G command can be terminated by entering an INTERRUPT (pressing the <Del> key).

h

The help command gives a short error message that explains the reason for the most recent ? diagnostic.

H

The Help command causes ed to enter a mode in which error messages are printed for all subsequent ? diagnostics. It will also explain the previous diagnostic if there was one. The H command alternately turns this mode on and off. It is initially off.

(.)i
text
.

The insert command inserts the given text before the addressed line; dot is left at the address of the last inserted line, or if there were no inserted lines, at the addressed line. This command differs from the a command only in the placement of the input text. Address 0 is not legal for this command.

(.,.+1)j

The join command joins contiguous lines by removing the appropriate newline characters. If only one address is given, this command does nothing.

(.)kx

The mark command marks the addressed line with name x, which must be a lowercase letter. The address 'x then addresses this line. Dot is unchanged.

(.,.)l

The list command prints the addressed lines in an unambiguous way. Some non-printable characters are printed in the following format:

\\, \a, \b, \f, \r, \t, \v

All other non-printable characters are printed in octal, and long lines are folded. An l command may be appended to any command other than e, f, r, or w. The $ character marks the end of each line.

(.,.)ma

The move command repositions the addressed line(s) after the line addressed by a. Address 0 is legal for a and causes the addressed line(s) to be moved to the beginning of the file. It is an error if address a falls within the range of moved lines. Dot is left at the last line moved.

(.,.)n

The number command prints the addressed lines, preceding each line by its line number and a tab character. Dot is left at the last line printed. The n command may be appended to any command other than e, f, r, or w.

(.,.)p

The print command prints the addressed lines. Dot is left at the last line printed. The p command may be appended to any command other than e, f, r, or w; for example, dp deletes the current line and prints the new current line.

P

The editor will prompt with a ``'' for all subsequent commands. The P command alternately turns this mode on and off. It is initially off.

q

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

Q

The editor exits without checking if changes have been made in the buffer since the last w command.

($)r file

The read command reads in the given file after the addressed line. If no filename is given, the currently remembered filename, if any, is used (see e and f commands). The currently remembered filename is not changed unless file is the very first filename mentioned since ed was invoked. 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. Dot is set to the address of the last line read in. If file begins with ``!'', the rest of the line is taken to be a shell command whose output is to be read. Such a shell command is not remembered as the current filename.

(.,.)s/regular-expression/replacement

(.,.)s/regular-expression/replacement/g

(.,.)s/regular-expression/replacement/l

(.,.)s/regular-expression/replacement/n

(.,.)s/regular-expression/replacement/p

(.,.)s/regular-expression/replacement/count

The substitute command searches each addressed line for an occurrence of the specified regular expression. In each line in which a match is found, all nonoverlapped matched strings are replaced by replacement if the global replacement indicator (the g flag) 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 newline may be used instead of ``/'' to delimit regular-expression and replacement. Dot is left at the address of the last line on which a substitution occurred.

The l, n and p flags all write to the standard output the last line on which a substitution was made, using the format specified by the l, n and p commands, respectively.

The count argument is any number in the range 1-512. This number indicates the instance of the pattern to be replaced on each addressed line.

An ampersand (&) appearing in replacement is replaced by the string matching the regular-expression on the current line. The special meaning of the ampersand in this context may be suppressed by preceding it with a backslash. The characters \n, where n is a digit, are replaced by the text matched by the n-th regular subexpression of the specified regular expression enclosed between ``\('' and ``\)''. When nested parenthesized subexpressions are present, n is determined by counting occurrences of ``\('' starting from the left. When the character ``%'' is the only character in replacement, the replacement used in the most recent substitute command is used as the replacement in the current substitute command. The ``%'' loses its special meaning when it is in a replacement string of more than one character or when it is preceded by a ``\''.

A line may be split by substituting a newline character into it. The newline in the replacement must be escaped by preceding it with a ``\''. Such a substitution cannot be done as part of a g or v command list.

(.,.)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). Dot is left at the address of the last line of the copy.

u

The undo command nullifies the effect of the most recent command that modified anything in the buffer, namely the most recent a, c, d, g, i, j, m, r, s, t, v, G, or V command.

(1,$)v/regular-expression/command list

This command is the same as the global command g except that the command list is executed with dot initially set to every line that does not match the regular expression.

(1,$)V/regular-expression/

This command is the same as the interactive global command G except that the lines that are marked during the first step are those that do not match the regular expression.

(1,$)w [ file ]

The write command writes the addressed lines into the named file. If the file does not exist, it is created with mode 666 (readable and writeable by everyone), unless the umask setting (see sh(C)) dictates otherwise. The currently remembered filename is not changed unless file is the very first filename mentioned since ed was invoked. If no filename is given, the currently remembered filename, if any, is used (see e and f commands), and dot remains. If the command is successful, the number of characters written is displayed. If file begins with an exclamation (!), the rest of the line is taken to be a shell command to which the addressed lines are supplied as the standard input. Such a shell command is not remembered as the current filename.

($)=

The line number of the addressed line is typed. Dot is unchanged by this command.

!shell command

The remainder of the line after the ``!'' is sent to the UNIX shell, sh, to be interpreted as a command. Within the text of that command, the unescaped character ``%'' is replaced with the remembered filename. If a ``!'' appears as the first character of the shell command, it is replaced with the text of the previous shell command. Thus, ``!!'' will repeat the last shell command. If any expansion is performed, the expanded line is echoed. Dot is unchanged.

(.+1)

An address alone on a line causes the addressed line to be printed. A <Return> alone on a line is equivalent to .+1p. This is useful for stepping forward through the editing buffer a line at a time.

ed has size limitations: {LINE_MAX} characters per line, {LINE_MAX} characters per global command list, 64 characters per filename, and 128KB characters in the buffer. (See getconf(C) for information on {LINE_MAX}.) The limit on the number of lines depends on the amount of user memory.

When reading a file, ed discards ASCII NUL characters and all characters after the last newline. Files (for example, a.out) that contain characters not in the ASCII set (bit 8 on) cannot be edited by ed.

If the closing delimiter of a regular expression or of a replacement string (for example, ``/'') would be the last character before a newline, that delimiter may be omitted, in which case the addressed line is printed. Thus, the following pairs of commands are equivalent:

s/s1/s2 s/s1/s2/p
g/s1 g/s1/p
?s1 ?s1?

Exit values

0

successful completion

>0

an error occurred

Diagnostics

?

command errors

? file

an inaccessible file

If changes have been made in the buffer since the last w command that wrote the entire buffer, ed warns the user if an attempt is made to destroy ed's buffer via the e or q commands by printing ``?'' and allowing you to continue editing. A second e or q command at this point will take effect. The dash (-) command-line option inhibits this feature.

Limitations

The ! command and the ! escape from the e, r, and w commands cannot be used if the the editor is invoked from a restricted shell (see sh(C)).

The sequence \n in a regular expression does not match any character.

The l command mishandles DEL.

Because 0 is an illegal address for the w command, it is not possible to create an empty file with ed.

If the editor input is coming from a command file; that is,

ed file < ed-cmd-file

the editor will exit at the first failure of a command in the command file.

Files

/tmp/e#

temporary; # is the process number

ed.hup

work is saved here if the terminal is hung up

See also

Standards conformance

ISO/IEC DIS 99452:1992, Information technology Portable Operating System Interface (POSIX) Part 2: Shell and Utilities (IEEE Std 1003.21992);
AT&T SVID Issue 2;
X/Open CAE Specification, Commands and Utilities, Issue 4, 1992.

red is conformant with:

AT&T SVID Issue 2;
X/Open Portability Guide, Issue 3, 1990: note that the X/Open CAE Specification, Commands and Utilities, Issue 4, 1992 marks this command as withdrawn.