Geek Gadgets 1/ADE-1.bin/ade-bin/info/ed.info

GNU Info File | 1996-10-12 | 28.7 KB | 770 lines

This is Info file ed.info, produced by Makeinfo-1.64 from the input
file ed.texinfo.

   This file documents the `ed' command, which has the purpose of
editing text files.

   Copyright (C) 1993 by the Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Foundation.


File: ed.info,  Node: Top,  Next: Intro,  Prev: (dir),  Up: (dir)



   This info file documents the `ed' text editor, as of release 0.2.
You may find in this document:

* Menu:

* Intro::                       An introduction to line editing with  `ed'
* Invoking ed::                 GNU `ed' command-line options
* Line addressing::             Specifying lines/ranges in the buffer
* Regular expressions::         Patterns for selecting text
* Commands::                    Commands recognized by GNU `ed'
* Limitations::                 Intrinsic limits of GNU `ed'
* Diagnostics::                 GNU `ed' error handling


File: ed.info,  Node: Intro,  Next: Invoking ed,  Prev: Top,  Up: Top

Intro
*****

   `ed' is a line-oriented text editor.  It is used to create, display,
modify and otherwise manipulate text files, both interactively and via
shell scripts.  A restricted version of `ed', `red', can only edit
files in the current directory and cannot execute shell commands.  `ed'
is the "standard" text editor in the sense that it is the original
editor for Unix, and thus widely available.  For most purposes,
however, it is superceded by full-screen editors such as Emacs and Vi.

   The sample sessions below illustrate some basic concepts of line
editing with `ed'.  We begin by creating a file, `sonnet', with some
help from Shakespeare.  As with the shell, all input to `ed' must be
followed by a newline character.  Comments begin with a `#'.

     $ ed
     # The `a' command is for appending text to the editor buffer.
     a
     No more be grieved at that which thou hast done.
     Roses have thorns, and filvers foutians mud.
     Clouds and eclipses stain both moon and sun,
     And loathsome canker lives in sweetest bud.
     .
     # Entering a single period on a line returns `ed' to command mode.
     # Now write the buffer to the file `sonnet' and quit:
     w sonnet
     183
     # `ed' reports the number of characters written.
     q
     $ ls -l
     total 2
     -rw-rw-r--    1 alm           183 Nov 10 01:16 sonnet
     $

   Editing with `ed' 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.  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. A "line" consists of the text up to and
including a newline character.  Input mode is terminated by entering a
single period (`.') on a line.

   In the next example, some typos are corrected in the file `sonnet'.

     $ ed sonnet
     183
     # Begin by printing the buffer to the terminal with the `p' command.
     # The `,' means ``all lines.''
     ,p
     No more be grieved at that which thou hast done.
     Roses have thorns, and filvers foutians mud.
     Clouds and eclipses stain both moon and sun,
     And loathsome canker lives in sweetest bud.
     # Select line 2 for editing.
     2
     Roses have thorns, and filvers foutians mud.
     # Use the substitute command, `s', to replace `filvers' with `silver',
     # and print the result.
     s/filvers/silver/p
     Roses have thorns, and silver foutians mud.
     # And correct the spelling of `fountains'.
     s/utia/untai/p
     Roses have thorns, and silver fountains mud.
     w sonnet
     183
     q
     $

   `ed' may be invoked with or without arguments *Note Invoking ed::.
When invoked with a FILE argument, 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 *Note Commands::, are lost.

   Since `ed' is line-oriented, we have to tell it which line, or range
of lines we want to edit.  In the above example, we do this by
specifying the line's number, or sequence in the buffer.  Alternatively,
we could have specified a unique string in the line, e.g., `/filvers/',
where the `/'s delimit the string in question.  Subsequent commands
affect only the selected line, a.k.a. the "current" line.  Portions of
that line are then replaced with the substitute command, whose syntax is
`s/OLD/NEW/'.

   Although `ed' accepts only one command per line, the print command
`p' is an exception, and may be appended to the end of most commands.

   In the next example, a title is added to our sonnet.

     $ ed sonnet
     183
     a
      Sonnet #50
     .
     ,p
     No more be grieved at that which thou hast done.
     Roses have thorns, and silver fountains mud.
     Clouds and eclipses stain both moon and sun,
     And loathsome canker lives in sweetest bud.
      Sonnet #50
     # The title got appended to the end; we should have used `0a'
     # to append ``before the first line.''
     # Move the title to its proper place.
     5m0p
      Sonnet #50
     # The title is now the first line, and the current line has been
     # set to this line as well.
     ,p
      Sonnet #50
     No more be grieved at that which thou hast done.
     Roses have thorns, and silver fountains mud.
     Clouds and eclipses stain both moon and sun,
     And loathsome canker lives in sweetest bud.
     wq sonnet
     195
     $

   When `ed' opens a file, the current line is initially set to the last
line of that file.   Similarly, the move command `m' sets the current
line to the last line moved.

   In summary: 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 second example above.  However even
there, the `s' command is applied to whole lines at a time.

   Structurally, `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.

   Related programs or routines are `vi (1)', `sed (1)', `regex (3)',
`sh (1)'.  Relevant documents are:

     Unix User's Manual Supplementary Documents: 12 -- 13

     B. W. Kernighan and P. J. Plauger: "Software Tools in Pascal",
     Addison-Wesley, 1981.


File: ed.info,  Node: Invoking ed,  Next: Line addressing,  Prev: Intro,  Up: Top

Invoking GNU `ed'
*****************

     ed [-] [-Gs] [-p STRING] [FILE]
     red [-] [-Gs] [-p STRING] [FILE]

`-G'
     Forces backwards compatibility.  This affects the behavior of the
     `ed' commands `G', `V', `f', `l', `m', `t' and `!!'.  If the
     default behavior of these commands does not seem familiar, then
     try invoking `ed' with this switch.

`-s'
`-'
     Suppresses diagnostics. This should be used if `ed''s standard
     input is from a script.

`-p STRING'
     Specifies a command prompt.  This may be toggled on and off with
     the `P' command.

   FILE specifies the name of a file to read.  If FILE is prefixed with
a bang (!), then it is interpreted as a shell command.  In this case,
what is read is the standard output of FILE executed via `sh (1)'.  To
read a file whose name begins with a bang, prefix the name with a
backslash (`\').  The default filename is set to FILE only if it is not
prefixed with a bang.


File: ed.info,  Node: Line addressing,  Next: Regular expressions,  Prev: Invoking ed,  Up: Top

Line addressing
***************

   An address represents the number of a line in the buffer.  `ed'
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
semicolon. The value of the first address in a range cannot exceed the
value of the 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 semicolon-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.

`.'
     The current line (address) in the buffer.

`$'
     The last line in the buffer.

`N'
     The Nth, line in the buffer where N is a number in the range `0,$'.

`-'
`^'
     The previous line.  This is equivalent to `-1' and may be repeated
     with cumulative effect.

`-N'
`^N'
     The Nth previous line, where N is a non-negative number.

`+'
     The next line.  This is equivalent to `+1' and may be repeated with
     cumulative effect.

`+N'
`WHITESPACE N'
     The Nth next line, where N is a non-negative number.  Whitespace
     followed by a number N is interpreted as `+N'.

`,'
`%'
     The first through last lines in the buffer.  This is equivalent to
     the address range `1,$'.

`;'
     The current through last lines in the buffer.  This is equivalent
     to the address range `.,$'.

`/RE/'
     The next line containing the regular expression RE.  The search
     wraps to the beginning of the buffer and continues down to the
     current line, if necessary.  `//' repeats the last search.

`?RE?'
     The previous line containing the regular expression RE.  The
     search wraps to the end of the buffer and continues up to the
     current line, if necessary.  `??' repeats the last search.

`'LC'
     The line previously marked by a `k' (mark) command, where LC is a
     lower case letter.


File: ed.info,  Node: Regular expressions,  Next: Commands,  Prev: Line addressing,  Up: Top

Regular expressions
*******************

   Regular expressions are patterns used in selecting text.  For
example, the `ed' 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:

`C'
     Any character C not listed below, including `{', `}', `(', `)',
     `<' and `>', matches itself.

`\C'
     Any backslash-escaped character C, other than `{', ``}', `(', `)',
     `<', `>', `b', `B', `w', `W', `+' and `?', matches itself.

`.'
     Matches any single character.

`[CHAR-CLASS]'
     Matches any single character in CHAR-CLASS.  To include a `]' 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:
          [.COL-ELM.]
          [=COL-ELM=]

     where COL-ELM is a "collating element" are interpreted according
     to `locale (5)' (not currently supported).  See `regex (3)' for an
     explanation of these constructs.

`[^CHAR-CLASS]'
     Matches any single character, other than newline, not in
     CHAR-CLASS.  CHAR-CLASS is defined as above.

`^'
     If `^' is the first character of a regular expression, then it
     anchors the regular expression to the beginning of a line.
     Otherwise, it matches itself.

`$'
     If `$' is the last character of a regular expression, it anchors
     the regular expression to the end of a line.  Otherwise, it matches
     itself.

`\(RE\)'
     Defines a (possibly null) subexpression RE.  Subexpressions may be
     nested.  A subsequent backreference of the form `\N', where N is a
     number in the range [1,9], expands to the text matched by the Nth
     subexpression. For example, the regular expression `\(a.c\)\1'
     matches the string `abcabc', but not `abcadc'.  Subexpressions are
     ordered relative to their left delimiter.

`*'
     Matches the single character regular expression or subexpression
     immediately preceding it zero or more times.  If `*' is the first
     character of a regular expression or subexpression, then it matches
     itself.  The `*' operator sometimes yields unexpected results.  For
     example, the regular expression `b*' matches the beginning of the
     string `abbb', as opposed to the substring `bbb', since a null
     match is the only left-most match.

`\{N,M\}'
`\{N,\}'
`\{N\}'
     Matches the single character regular expression or subexpression
     immediately preceding it at least N and at most M times.  If M is
     omitted, then it matches at least N times.  If the comma is also
     omitted, then it matches exactly N times.  If any of these forms
     occurs first in a regular expression or subexpression, then it is
     interpreted literally (i.e., the regular expression `\{2\}'
     matches the string `{2}', and so on).

`\<'
`\>'
     Anchors the single character regular expression or subexpression
     immediately following it to the beginning (in the case of `\<') or
     ending (in the case of `\>') of a "word", i.e., in ASCII, a
     maximal string of alphanumeric characters, including the
     underscore (_).

   The following extended operators are preceded by a backslash `\' to
distinguish them from traditional `ed' syntax.

`\`'
`\''
     Unconditionally matches the beginning `\`' or ending `\'' of a
     line.

`\?'
     Optionally matches the single character regular expression or
     subexpression immediately preceding it.  For example, the regular
     expression `a[bd]\?c' matches the strings `abc', `adc' and `ac'.
     If `\?' occurs at the beginning of a regular expressions or
     subexpression, then it matches a literal `?'.

`\+'
     Matches the single character regular expression or subexpression
     immediately preceding it one or more times.  So the regular
     expression `a+' is shorthand for `aa*'.  If `\+' occurs at the
     beginning of a regular expression or subexpression, then it
     matches a literal `+'.

`\b'
     Matches the beginning or ending (null string) of a word.  Thus the
     regular expression `\bhello\b' is equivalent to `\<hello\>'.
     However, `\b\b' is a valid regular expression whereas `\<\>' is
     not.

`\B'
     Matches (a null string) inside a word.

`\w'
     Matches any character in a word.

`\W'
     Matches any character not in a word.


File: ed.info,  Node: Commands,  Next: Limitations,  Prev: Regular expressions,  Up: Top

Commands
********

   All `ed' commands are single characters, though some require
additonal 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.

   `ed' recognizes the following commands.  The commands are shown
together with the default address or address range supplied if none is
specified (in parenthesis).

`(.)a'
     Appends text to the buffer after the addressed line, which may be
     the address `0' (zero).  Text is entered in input mode.  The
     current address is set to last line entered.

`(.,.)c'
     Changes lines in the buffer.  The addressed lines are deleted from
     the buffer, and text is appended in their place.  Text is entered
     in input mode.  The current address is set to last line entered.

`(.,.)d'
     Deletes the addressed lines from the buffer.  If there is a line
     after the deleted range, then the current address is set to this
     line.  Otherwise the current address is set to the line before the
     deleted range.

`e FILE'
     Edits FILE, and sets the default filename.  If FILE is not
     specified, then the default filename is used.  Any lines in the
     buffer are deleted before the new file is read.  The current
     address is set to the last line read.

`e !COMMAND'
     Edits the standard output of `!COMMAND', (see the `!' command
     below).  The default filename is unchanged.  Any lines in the
     buffer are deleted before the output of COMMAND is read.  The
     current address is set to the last line read.

`E FILE'
     Edits FILE unconditionally.  This is similar to the `e' command,
     except that unwritten changes are discarded without warning.  The
     current address is set to the last line read.

`f FILE'
     Sets the default filename to FILE.  If FILE is not specified, then
     the default unescaped filename is printed.

`(1,$)g /RE/COMMAND-LIST'
     Applies COMMAND-LIST to each of the addressed lines matching a
     regular expression RE.  The current address is set to the line
     currently matched before COMMAND-LIST is executed.  At the end of
     the `g' command, the current address is set to the last line
     affected by COMMAND-LIST.

     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'.  By
     default, a newline alone in COMMAND-LIST is equivalent to a `p'
     command.  If `ed' is invoked with the command-line option `-G',
     then a newline in COMMAND-LIST is equivalent to a `.+1p' command.

`(1,$)G /RE/'
     Interactively edits the addressed lines matching a regular
     expression RE.  For each matching line, the line is printed, the
     current address is set, and the user is prompted to enter a
     COMMAND-LIST.  At the end of the `G' command, the current address
     is set to the last line affected by (the last) COMMAND-LIST.

     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.

`H'
     Toggles the printing of error explanations.  By default,
     explanations are not printed.  It is recommended that ed scripts
     begin with this command to aid in debugging.

`h'
     Prints an explanation of the last error.

`(.)i'
     Inserts text in the buffer before the current line.  Text is
     entered in input mode.  The current address is set to the last
     line entered.

`(.,.+1)j'
     Joins the addressed lines.  The addressed lines are deleted from
     the buffer and replaced by a single line containing their joined
     text.  The current address is set to the resultant line.

`(.)k LC'
     Marks a line with a lower case letter LC.  The line can then be
     addressed as `'LC' (i.e., a single quote followed by LC) in
     subsequent commands.  The mark is not cleared until the line is
     deleted or otherwise modified.

`(.,.)l'
     Prints the addressed lines unambiguously.  If invoked from a
     terminal, `ed' pauses at the end of each page until a newline is
     entered.  The current address is set to the last line printed.

`(.,.)m(.)'
     Moves lines in the buffer.  The addressed lines are moved to after
     the right-hand destination address, which may be the address `0'
     (zero).  The current address is set to the last line moved.

`(.,.)n'
     Prints the addressed lines along with their line numbers.  The
     current address is set to the last line printed.

`(.,.)p'
     Prints the addressed lines.  If invoked from a terminal, `ed'
     pauses at the end of each page until a newline is entered.  The
     current address is set to the last line printed.

`P'
     Toggles the command prompt on and off.  Unless a prompt is
     specified with command-line option `-p STRING', the command prompt
     is by default turned off.

`q'
     Quits `ed'.

`Q'
     Quits `ed' unconditionally.  This is similar to the `q' command,
     except that unwritten changes are discarded without warning.

`($)r FILE'
     Reads FILE to after the addressed line.  If FILE is not specified,
     then the default filename is used.  If there is no default
     filename prior to the command, then the default filename is set to
     FILE.  Otherwise, the default filename is unchanged.  The current
     address is set to the last line read.

`($)r !COMMAND'
     Reads to after the addressed line the standard output of
     `!command', (see the `!' command below).  The default filename is
     unchanged.  The current address is set to the last line read.

`(.,.)s /RE/REPLACEMENT/'
`(.,.)s /RE/REPLACEMENT/g'
`(.,.)s /RE/REPLACEMENT/n'
     Replaces text in the addressed lines matching a regular expression
     RE with REPLACEMENT.  By default, only the first match in each
     line is replaced.  If the `g' (global) suffix is given, then every
     match to be replaced.  The `n' suffix, where N is a postive
     number, causes only the Nth match to be replaced.  It is an error
     if no substitutions are performed on any of the addressed lines.
     The current address is set the last line affected.

     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 Mth 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
     (`\').

`(.,.)s'
     Repeats the last substitution.  This form of the `s' command
     accepts a count suffix N, or any combination of the characters
     `r', `g', and `p'.  If a count suffix N is given, then only the
     Nth match is replaced.  The `r' suffix causes the regular
     expression of the last search to be used instead of the that of
     the last substitution.  The `g' suffix toggles the global suffix
     of the last substitution.  The `p' suffix toggles the print suffix
     of the last substitution The current address is set to the last
     line affected.

`(.,.)t(.)'
     Copies (i.e., transfers) the addressed lines to after the
     right-hand destination address, which may be the address `0'
     (zero).  The current address is set to the last line copied.

`u'
     Undoes the last command and restores the current address to what
     it was before the command.  The global commands `g', `G', `v', and
     `V' are treated as a single command by undo.  `u' is its own
     inverse.

`(1,$)v /RE/COMMAND-LIST'
     Applies COMMAND-LIST to each of the addressed lines not matching a
     regular expression RE.  This is similar to the `g' command.

`(1,$)V /RE/'
     Interactively edits the addressed lines not matching a regular
     expression RE.  This is similar to the `G' command.

`(1,$)w FILE'
     Writes the addressed lines to FILE.  Any previous contents of FILE
     is lost without warning.  If there is no default filename, then
     the default filename is set to FILE, otherwise it is unchanged.
     If no filename is specified, then the default filename is used.
     The current address is unchanged.

`(1,$)wq FILE'
     Writes the addressed lines to FILE, and then executes a `q'
     command.

`(1,$)w !COMMAND'
     Writes the addressed lines to the standard input of `!COMMAND',
     (see the `!' command below).  The default filename and current
     address are unchanged.

`(1,$)W FILE'
     Appends the addressed lines to the end of FILE.  This is similar
     to the `w' command, expect that the previous contents of file is
     not clobbered.  The current address is unchanged.

`(.)x'
     Copies (puts) the contents of the cut buffer to after the
     addressed line.  The current address is set to the last line
     copied.

`(.,.)y'
     Copies (yanks) the addressed lines to the cut buffer.  The cut
     buffer is overwritten by subsequent `y', `s', `j', `d', or `c'
     commands.  The current address is unchanged.

`(.+1)z N'
     Scrolls N lines at a time starting at addressed line.  If N is not
     specified, then the current window size is used.  The current
     address is set to the last line printed.

`! COMMAND'
     Executes COMMAND via `sh (1)'.  If the first character of COMMAND
     is `!', then it is replaced by text of the previous `!COMMAND'.
     `ed' 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.

`(.,.)#'
     Begins a comment;  the rest of the line, up to a newline, is
     ignored.  If a line address followed by a semicolon is given, then
     the current address is set to that address.  Otherwise, the
     current address is unchanged.

`($)='
     Prints the line number of the addressed line.

`(.+1)newline'
     Prints the addressed line, and sets the current address to that
     line.


File: ed.info,  Node: Limitations,  Next: Diagnostics,  Prev: Commands,  Up: Top

Limitations
***********

   The buffer files are kept in `/tmp/ed.*'.  If the terminal hangs up,
`ed' attempts to write the buffer to file `ed.hup'.

   `ed' 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 `int's.


File: ed.info,  Node: Diagnostics,  Prev: Limitations,  Up: Top

Diagnostics
***********

   When an error occurs, if `ed''s input is from a regular file or here
document, then it exits, otherwise it prints a `?' and returns to
command mode.  An explanation of the last error can be printed with the
`h' (help) command.

If the `u' (undo) command occurs in a global command list, then the
command list is executed only once.

   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.

   `ed' exits with 0 if no errors occurred; otherwise >0.



Tag Table:
Node: Top894
Node: Intro1524
Node: Invoking ed7498
Node: Line addressing8535
Node: Regular expressions11591
Node: Commands16977
Node: Limitations27863
Node: Diagnostics28481

End Tag Table