+.TH ED 1 9/14/79
+.UC
+.if t .ds q \(aa
+.if n .ds q '
+.SH NAME
+ed \- text editor
+.SH SYNOPSIS
+.B ed
+[
+.B \-
+] [
+.BR \-p [prompt]
+] [
+.B \-u
+] [
+.B \-x
+] [ name ]
+.SH DESCRIPTION
+.I Ed
+is the standard text editor.
+.PP
+If a
+.I name
+argument is given,
+.I ed
+simulates an
+.I e
+command (see below)\| on the named file; that is to say,
+the file is read into
+.I ed's
+buffer so that it can be edited.
+If
+.B \-p
+is present,
+.I ed
+prompts for commands
+with `* '
+(or
+.I prompt
+if given.)
+If
+.B \-u
+is present,
+all lower case text in the buffer
+is converted to upper case.
+If
+.B \-x
+is present, an
+.I x
+command is simulated first to handle an encrypted file.
+The optional
+.B \-
+suppresses the printing
+of explanatory output
+and should be used
+when the standard input is
+an editor script.
+.PP
+.I Ed
+operates on a copy of any file it is editing; changes made
+in the copy have no effect on the file until a
+.IR w ""
+(write)\|
+command is given.
+The copy of the text being edited resides
+in a temporary file called the
+.IR buffer .
+.PP
+Commands to
+.I ed
+have a simple and regular structure: zero or
+more
+.I addresses
+followed by a single character
+.I command,
+possibly
+followed by parameters to the command.
+These addresses specify one or more lines in the buffer.
+Missing addresses are supplied by default.
+.PP
+In general, only one command may appear on a line.
+Certain commands allow the
+addition of text to the buffer.
+While
+.I ed
+is accepting text, it is said
+to be in
+.I "input mode."
+In this mode, no commands are recognized;
+all input is merely collected.
+Input mode is left by typing a period `\fB.\fR' alone at the
+beginning of a line.
+.PP
+.I Ed
+supports a limited form of
+.I "regular expression"
+notation.
+A regular expression specifies
+a set of strings of characters.
+A member of this set of strings is said to be
+.I matched
+by the regular expression.
+In the following specification for regular expressions
+the word `character' means any character but newline.
+.IP 1.
+Any character except a special character
+matches itself.
+Special characters are
+the regular expression delimiter plus
+.RB \e\|[\| .
+and sometimes ^\|*\|$.
+.IP 2.
+A
+.B .
+matches any character.
+.IP 3.
+A \e followed by any character except a digit or (\|) matches that character.
+.IP 4.
+A nonempty string
+.I s
+bracketed
+.RI [ \|s\| ]
+(or
+.RI [^ s\| ])
+matches any character in (or not in)
+.I s.
+In
+.I s,
+\e has no special meaning, and ] may only appear as
+the first letter.
+A substring
+.I a\-b,
+with
+.I a
+and
+.I b
+in ascending ASCII order, stands for the inclusive
+range of ASCII characters.
+.IP 5.
+A regular expression of form 1-4 followed by * matches a sequence of
+0 or more matches of the regular expression.
+.IP 6.
+A regular expression,
+.I x,
+of form 1-8, bracketed
+.RI \e( \|x\| \e)
+matches what
+.I x
+matches.
+.IP 7.
+A \e followed by a digit
+.I n
+matches a copy of the string that the
+bracketed regular expression beginning with the
+.IR n th
+\e( matched.
+.IP 8.
+A regular expression of form 1-8,
+.I x,
+followed by a regular expression of form 1-7,
+.I y
+matches a match for
+.I x
+followed by a match for
+.I y,
+with the
+.I x
+match being as long as possible while still permitting a
+.I y
+match.
+.IP 9.
+A regular expression of form 1-8 preceded by ^
+(or followed by $), is constrained to matches that
+begin at the left (or end at the right) end of a line.
+.IP 10.
+A regular expression of form 1-9 picks out the
+longest among the leftmost matches in a line.
+.IP 11.
+An empty regular expression stands for a copy of the
+last regular expression encountered.
+.PP
+Regular expressions are used in addresses to specify
+lines and in one command
+(see
+.I s
+below)\|
+to specify a portion of a line which is to be replaced.
+If it is desired to use one of
+the regular expression metacharacters as an ordinary
+character, that character may be preceded by `\e'.
+This also applies to the character bounding the regular
+expression (often `/')\| and to `\e' itself.
+.PP
+To understand addressing in
+.I ed
+it is necessary to know that at any time there is a
+.I "current line."
+Generally speaking, the current line is
+the last line affected by a command; however,
+the exact effect on the current line
+is discussed under the description of
+the command.
+Addresses are constructed as follows.
+.TP
+1.
+The character `\fB.\fR' addresses the current line.
+.TP
+2.
+The character `$' addresses the last line of the buffer.
+.TP
+3.
+A decimal number
+.I n
+addresses the
+.IR n -th
+line of the buffer.
+.TP
+4.
+`\(fm\fIx\fR' addresses the line marked with the name
+.IR x ,
+which must be a lower-case letter.
+Lines are marked with the
+.I k
+command described below.
+.TP
+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.
+.TP
+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.
+.TP
+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.
+.TP
+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 `\fB.\fR\-5'.
+.TP
+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.
+.TP
+10.
+To maintain compatibility with earlier versions of the editor,
+the character `^' in addresses is
+equivalent to `\-'.
+.PP
+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.
+.PP
+Addresses are separated from each other typically by a comma
+`\fB,\fR'.
+They may also be separated by a semicolon
+`\fB;\fR'.
+In this case the current line `\fB.\fR' 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,$'.
+.PP
+In the following list of
+.I 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.
+.PP
+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.
+.TP 5
+.RB (\| .\| )\|a
+.br
+.ns
+.TP 5
+<text>
+.br
+.ns
+.TP 5
+.B .
+.br
+The append command reads the given text
+and appends it after the addressed line.
+`\fB.\fR' 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.
+.TP 5
+.RB (\| .\| ,\ .\| )\|c
+.br
+.ns
+.TP 5
+<text>
+.br
+.ns
+.TP 5
+.B .
+.br
+The change
+command deletes the addressed lines, then accepts input
+text which replaces these lines.
+`\fB.\fR' is left at the last line input; if there were none,
+it is left at the line preceding the deleted lines.
+.TP 5
+.RB (\| .\| ,\ .\| )\|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.
+.TP 5
+e filename
+The edit
+command causes the entire contents of the buffer to be deleted,
+and then the named file to be read in.
+`\fB.\fR' 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
+.I r
+or
+.I w
+command.
+If `filename' is missing, the remembered name is used.
+.TP 5
+E filename
+This command is the same as
+.I e,
+except that no diagnostic results when no
+.I w
+has been given since the last buffer alteration.
+.TP 5
+f filename
+The filename command prints the currently remembered file name.
+If `filename' is given,
+the currently remembered file name is changed to `filename'.
+.TP 5
+(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 `\fB.\fR' 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 `\e'.
+.I A,
+.I i,
+and
+.I c
+commands and associated input are permitted;
+the `\fB.\fR' terminating input mode may be omitted if it would be on the
+last line of the command list.
+The commands
+.I g
+and
+.I v
+are not permitted in the command list.
+.TP 5
+.RB (\| .\| )\|i
+.ns
+.TP 5
+<text>
+.br
+.ns
+.TP 5
+.B .
+.br
+This command inserts the given text before the addressed line.
+`\fB.\fR' is left at the last line input, or, if there were none,
+at the line before the addressed line.
+This command differs from the
+.I a
+command only in the placement of the
+text.
+.TP 5
+.RB (\| .\| ,\ . +1)\|j
+This command joins the addressed lines into a single line;
+intermediate newlines simply disappear.
+`\fB.\fR' is left at the resulting line.
+.TP 5
+( \fB. \fR)\|k\fIx\fR
+The mark command marks the addressed line with
+name
+.I x,
+which must be a lower-case letter.
+The address form `\(fm\fIx\fR' then addresses this line.
+.ne 2.5
+.TP 5
+.RB (\| .\| ,\ .\| )\|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
+.I l
+command may be placed on the same line after any non-i/o
+command.
+.TP 5
+.RB (\| .\| ,\ .\| )\|m\fIa
+The move command repositions the addressed lines after the line
+addressed by
+.IR a .
+The last of the moved lines becomes the current line.
+.TP 5
+.RB (\| .\| ,\ .\| )\|n
+The number command prints the addressed lines
+with line numbers and a tab at the left.
+.TP 5
+.RB (\| .\| ,\ .\| )\|p
+The print command prints the addressed lines.
+`\fB.\fR'
+is left at the last line printed.
+The
+.I p
+command
+may
+be placed on the same line after any non-i/o command.
+.TP
+.RB (\| .\| ,\ .\| )\|P
+This command is a synonym for
+.I p.
+.TP 5
+q
+The quit command causes
+.I ed
+to exit.
+No automatic write
+of a file is done.
+.TP 5
+Q
+This command is the same as
+.I q,
+except that no diagnostic results when no
+.I w
+has been given since the last buffer alteration.
+.TP 5
+($)\|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
+.I e
+and
+.I f
+commands)\|.
+The file name is remembered if there was no
+remembered file name already.
+Address `0' is legal for
+.I 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.
+`\fB.\fR' is left at the last line read in from the file.
+.TP 5
+(\| \fB.\fR\|, \fB.\fR\|)\|s/regular expression/replacement/ or,
+.br
+.ns
+.TP 5
+(\| \fB.\fR\|, \fB.\fR\|)\|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.
+`\fB.\fR' is left at the last line substituted.
+.IP
+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 `\e'.
+The characters
+.I `\|\en'
+where
+.I n
+is a digit,
+are replaced by the text matched by the
+.IR n -th
+regular subexpression
+enclosed between `\e(' and `\e)'.
+When
+nested, parenthesized subexpressions
+are present,
+.I n
+is determined by counting occurrences of `\e(' starting from the left.
+.IP
+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 `\e'.
+.IP
+One or two trailing delimiters may be omitted,
+implying the `p' suffix.
+The special form `s' followed by
+.I no
+delimiters
+repeats the most recent substitute command
+on the addressed lines.
+The `s' may be followed by the letters
+.B r
+(use the most recent regular expression for the
+left hand side, instead of the most recent
+left hand side of a substitute command),
+.B p
+(complement the setting of the
+.I p
+suffix from the previous substitution), or
+.B g
+(complement the setting of the
+.I g
+suffix).
+These letters may be combined in any order.
+.TP 5
+.RB (\| .\| ,\ .\| )\|t\|\fIa
+This command acts just like the
+.I m
+command, except that a copy of the addressed lines is placed
+after address
+.I a
+(which may be 0).
+`\fB.\fR' is left on the last line of the copy.
+.TP 5
+.RB (\| .\| ,\ .\| )\|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
+.I a, c, d, g, i, k, m, r, s, t,
+and
+.I v.
+For purposes of undo,
+.I g
+and
+.I v
+are considered to be a single buffer modifying command.
+Undo is its own inverse.
+.IP
+When
+.I 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
+.I u
+can only undo the effect of the most recent
+substitute on the current line.
+This restricted undo also applies to editor scripts
+when
+.I ed
+is invoked with the
+.B -
+option.
+.TP 5
+(1, $)\|v/regular expression/command list
+This command is the same as the global command
+.I g
+except that the command list is executed
+.I g
+with `\fB.\fR' initially set to every line
+.I except
+those
+matching the regular expression.
+.TP 5
+(1, $)\|w filename
+.br
+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
+.I e
+and
+.I f
+commands)\|.
+`\fB.\fR' is unchanged.
+If the command is successful, the number of characters written is
+printed.
+.TP
+(1, $)\|W filename
+This command is the same as
+.I w,
+except that the addressed lines are appended to the file.
+.TP 5
+(1, $)\|wq filename
+This command is the same as
+.I w
+except that afterwards a
+.I q
+command is done,
+exiting the editor
+after the file is written.
+.TP 5
+x
+A key string is demanded from the standard input.
+Later
+.I r, e
+and
+.I w
+commands will encrypt and decrypt the text
+with this key by the algorithm of
+.IR crypt (1).
+An explicitly empty key turns off encryption.
+.RB (\| .\| +1)\|z or,
+.br
+.ns
+.TP 5
+.RB (\| .\| +1)\|z\fIn
+This command scrolls through the buffer starting at the addressed line.
+22 (or
+.I n,
+if given)
+lines are printed.
+The last line printed becomes the current line.
+The value
+.I n
+is sticky, in that it becomes the default for
+future
+.I z
+commands.
+.TP 5
+($)\|=
+The line number of the addressed line is typed.
+`\fB.\fR' is unchanged by this command.
+.TP 5
+!<shell command>
+The remainder of the line after the `!' is sent
+to
+.IR sh (1)
+to be interpreted as a command.
+.RB ` . '
+is unchanged.
+.TP 5
+.RB (\| . +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,
+.I ed
+prints the range of lines.
+If they are separated by a semicolon,
+the second line is printed.
+.PP
+If an interrupt signal (ASCII DEL)\| is sent,
+.I ed
+prints `?interrupted'
+and returns to its command level.
+.PP
+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.
+.PP
+When reading a file,
+.I ed
+discards ASCII NUL characters
+and all characters after the last newline.
+It refuses to read files containing non-ASCII characters.
+.SH FILES
+/tmp/e*
+.br
+edhup: work is saved here if terminal hangs up
+.SH "SEE ALSO"
+B. W. Kernighan,
+.I
+A Tutorial Introduction to the ED Text Editor
+.br
+B. W. Kernighan,
+.I Advanced editing on UNIX
+.br
+sed(1), crypt(1)
+.SH DIAGNOSTICS
+`?name' for inaccessible file;
+`?self-explanitory message'
+for other errors.
+.PP
+To protect against throwing away valuable work,
+a
+.I q
+or
+.I e
+command is considered to be in error, unless a
+.I w
+has occurred since the last buffer change.
+A second
+.I q
+or
+.I e
+will be obeyed regardless.
+.SH BUGS
+The
+.I l
+command mishandles DEL.
+.br
+The
+.I undo
+command causes marks to be lost on affected lines.
+.br
+The
+.I x
+command,
+.B -x
+option,
+and
+special treatment of hangups
+only work on UNIX.
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