Sortix cross-volatile manual

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NAME

ed — text editor

SYNOPSIS

ed	[-] [-s] [-p string] [file]

DESCRIPTION

ed is a line-oriented text editor. It is used to create, display, modify, and otherwise manipulate text files. If invoked with a file argument, then 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 are lost.

Editing 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.

A typical command might look like:

,s/old/new/g

which replaces all occurrences of the string “old” with “new”.

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. Lines consist of text up to and including a newline character. Input mode is terminated by entering a single period (‘.’) on a line.

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 example above. However, even here, the s command is applied to whole lines at a time.

In general, 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.

Many ed commands and line addresses support basic regular expressions (BREs). See re_format(7) for more information on regular expressions.

The options are as follows:

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 (e.g., ‘+’, ‘-’, 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 semi-colon. The value of the first address in a range cannot exceed the value of 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 semi-colon-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:

COMMANDS

All ed commands are single characters, though some require additional 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.

ed recognizes the following commands. The commands are shown together with the default address or address range supplied if none is specified (in parentheses), and other possible arguments on the right.

(.)a: Appends text to the buffer after the addressed line. 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 !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. If no lines were matched, the current line number remains unchanged.

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. A newline alone in command-list is equivalent to a p 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. If no lines were matched, the current line number remains unchanged.

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.
(.)klc: 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. 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. The current address is set to the last line printed.
P: Toggles the command prompt on and off. Unless a prompt was specified with the 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.
($)r file: Reads file to after the addressed line. If file is not specified, then the default filename is used. If there was no default filename prior to the command, then the default filename is set to file. Otherwise, the default filename is unchanged. The current address is set to the last line read.
($)r !command: Reads to after the addressed line the standard output of !command, (see !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 is replaced. The n suffix, where n is a positive 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 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,$)w file: Writes the addressed lines to file. Any previous contents of file are lost without warning. If there is no default filename, then the default filename is set to file, otherwise it is unchanged. If no filename is specified, then the default filename is used. The current address is unchanged.
(1,$)wq file: Writes the addressed lines to file, and then executes a q command.
(1,$)w !command: Writes the addressed lines to the standard input of !command, (see !command below). The default filename and current address are unchanged.
(1,$)W file: Appends the addressed lines to the end of file. This is similar to the w command, except that the previous contents of file are not clobbered. The current address is unchanged.
(.+1)zn: 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.
($)=: Prints the line number of the addressed line.
(.+1)newline: Prints the addressed line, and sets the current address to that line.
!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.

ASYNCHRONOUS EVENTS

FILES

EXIT STATUS

The ed utility exits 0 on success, and >0 if an error occurs.

DIAGNOSTICS

When an error occurs, ed prints a ‘?’ and either returns to command mode or exits if its input is from a script. An explanation of the last error can be printed with the h (help) command.

Since the g (global) command masks any errors from failed searches and substitutions, it can be used to perform conditional operations in scripts; e.g.,

g/old/s//new/

replaces any occurrences of “old” with “new”.

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

If diagnostics are not disabled, 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.

STANDARDS

The ed utility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification.

The commands s (to repeat the last substitution), W, wq, and z as well as the address specifier ‘%’ are extensions to that specification.

The IEEE Std 1003.1-2008 (“POSIX.1”) specification says the ‘^’ address specifier is neither required nor prohibited; additionally, it says behaviour for the - option is “unspecified”.

The IEEE Std 1003.1-2008 (“POSIX.1”) specification says the l command should mark the ends of lines with a ‘$’ character, and that ‘$’ characters within the text should be output preceded by a backslash; this implementation does not support that.

HISTORY

An ed command appeared in Version 1 AT&T UNIX.

CAVEATS

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.