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HP-UX 11i Version 3: February 2007

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ied — input editor and command history for interactive programs


ied [-dirt] [-h file] [-k charmap] [-p prompt] [-s size] utility [arguments]...


The ied utility command is intended to act as an interface between the user and an interactive program such as bc, bs, or a shell, providing most of the line editing and history functionality found in the Korn shell. ied interprets the utility name as the command to be executed, and passes arguments as the arguments to the utility. Subsequent input to utility then has access to editing and history functions very similar to those provided by ksh.

ied monitors the state of the pty it uses to run the command; whenever the application it is running changes the state from the state of the tty when ied started, ied becomes "transparent". This allows programs to do shell escapes to screen-smart programs. In general, ied should not in any way interfere with any action taken by any program for which it provides a front end. This includes Korn shell itself: in this case ied would provide history for any application that was run by ksh, and ksh would provide its own independent history. In a useful extreme case, ied can be used as a front end to the login shell (which might be ksh or csh). In this case, all applications that use normal line editing gain line editing and history, sharing a single history. The shell would continue to have its own independent history if it provides such a mechanism.

When ied is in its transparent mode, no history is saved. In particular the ex mode of vi does not use normal line editing (rather, it simulates it) and ied cannot provide history in this case. The Subject: and address line editing of mailx also cannot be edited with ied.


Several options and command-line arguments control ied's operation:


Debug mode. Print information about the operation of the program. It is best used to determine if a program puts ied into transparent mode unexpectedly.

-h filename

Keep the history in a file named filename. If a file of that name already exists and is a history file, the latter part of it (the last size lines as specified by the -s option) is used as the initial value of the history. If the -h option is not used, the environment variable IEDHISTFILE is used to supply the name. If neither is present, an unnamed temporary file is used, and no initial value is provided.


Force interactive mode. Normally ied simply execs the command to which it is asked to be a front end when the standard input is not a tty (this allows aliases to be used for commands used in shells without interfering with their operation). This option forces ied to remain as a front end, and all editing functions are in place. This permits a utility that behaves differently in interactive and batch modes to be driven from a pipe or file in interactive mode. This is particularly useful in testing commands that make this distinction.

-k charmap

charmap is a file of 256 or fewer lines. The line number in the file is the ordinal of a character as seen as input by ied, and the character on the line is the character generated as output (and also used as editing characters). This allows remapping of (ordinary) keys such as for a Dvorak keyboard. Characters must start in column one of each line, and be represented as 1-4 characters followed by a space or the newline character for the next line. Characters after the space are ignored as comments. Single-character entries represent themselves. Two-character entries where the first character is a circumflex (^) converts the second character to the corresponding control character. Two-character sequences where the first character is backslash (\) use the C language conventions:

\rreturn\fform feed
\ttab\vvertical tab

Three- and four-character sequences must be \nn or \nnn, giving the octal value for the character. If charmap is less than 256 lines long, the remaining characters are mapped to themselves.

-p prompt

Many commands do not prompt when ready for input. ied approximates a prompting mechanism for such commands. This is not always perfectly successful, but for many commands it helps. In the worst case, the prompt is interspersed with output in the wrong location. prompt is a string as used in the format argument to printf() (see printf(3S)). The only % conversions that can be included are up to one instance of %d which is converted to the sequential number of the command, and any number of occurrences of %% which is treated as a literal % character. Prompting is suppressed when ied is operating in transparent mode.


This sets "non-raw" mode. Normally ied uses its own editing capabilities when reading simple text. This causes ied to use tty line discipline most of the time. The disadvantage of the default mode is that more context switches and general processing are required. The advantage is that ied is more transparent. For example, to specifically send an end-of-file in the non-raw mode requires that the end-of-file character (usually Ctrl-D) be followed by a carriage return. Similarly the "literal next" function (Ctrl-V) cannot escape the line-erase and line-kill functions in non-raw mode.

-s size

This option specifies the size of the history buffer. When ied is started with an existing history file, approximately the last size lines are available to the history mechanism (the number is not guaranteed to be exactly size). Other lines in the file are retained until such time as ied is started on that history file and it exceeds approximately 4K bytes in size, at which time ied discards older entries at the beginning of the file until it is near 4 KB in size. Since this occurs only at startup, history files can grow to be quite large between restarts. Larger values of size make the process image larger.

If -s is not specified, the value of the environment variable IEDHISTSIZE is used. If neither is specified, a default is used.


Set transparent mode. This forces ied to permanently be in transparent mode (as discussed above). It is primarily useful with -i for some classes of automated processing. In particular, it is useful for driving a command if the command takes as input what ied would interpret as editing characters. Thus with the appropriate combinations of -i and -t, it is possible to drive an editor such as vi or a screen-smart application from a batch file.

Should something go wrong with ied, the SIGQUIT signal, repeated 3 times, usually aborts ied. The exception is the case of a fully transparent application, where ied must be killed from another window or terminal. This is really relevant only when there is no way to direct the serviced process to terminate itself.

The editing capabilities of ied are essentially those found in ksh. Only those that differ from ksh are described below. As in ksh, the style of editing is determined from the environment variable VISUAL, or from EDITOR if VISUAL is not specified. The value examined should end in vi, emacs, or gmacs to specify an editor type. If it does not, ied does no editing, and history is not accessible.

In vi mode:


Join lines. Considering the most recently edited line (which is empty immediately after a line is sent to the application) to be the "last line" of the history, the current line being displayed from the history is appended to the end of the last line, and the position in the history is reset to be at the last line which is then displayed. A space is inserted between the old and new text on the last line. The cursor is left on that space. Because ied's understanding of line continuation is minimal, this is useful for editing long statements.


Not supported.


Not supported.


Sends nothing to the application, but inserts the line in the history (useful for adding comments to history file).


(File name expansion). Not supported.


Macro expansion. Not supported.

Note however that ksh has a rarely-used function _ that substitutes words from the previous line (this is not the macro $_, but rather an editor command). If a preceding count is given, it uses the countth word of the last line. This is much more useful with ied.

In emacs/gmacs mode:

M-*, M-=, M-ESC

(file name expansion) Not supported.

Note that the command M-. (and its synonym M-_) provide the same functionality as the vi mode _ command.

Macro expansion.

Not supported.


Although supported, it may not always appear correctly on the screen. The ^L command can be used to redraw the line. See below for the discussion on prompting.


Add interactive editing to the bc command:

ied bc

Execute vi on testfile using comands taken from script:

cat script | ied -i -t vi testfile

Note that, without the use of ied, vi would misbehave because its standard input would not be a terminal device. In this case, the -t is not required because vi puts itself in raw mode, but for an application that does not, -t might be required.

The command line

ied -i -t grep '^x:' data_file | tee x_lines

searches the file data_file for lines beginning with x:, sending one copy to the terminal and a second to file x_lines, just like the command line

grep '^x:' data_file | tee x_lines

The difference is that in the command line without ied, grep writes directly to a pipe, and thus buffers its output. If data_file is very large and not many lines match the pattern, output to the terminal is delayed. By using ied, the output of grep goes to a pty instead, which causes grep to output each line as it is ready.


Since ied cannot know everything about every application, it is possible that it can become confused, with either the timing or the prompt being out of phase with the application. Since the use of ied is never required, it is the user's choice to determine whether the application is more usable with or without ied. In general, however, programs that do not confuse ied are usually also the most likely to benefit from its use.

ied tries to intuit the currently active prompt when it is not providing one itself. However, this is not always successful. Even when it is successful, the timing of ied and the serviced command may occasionally confuse the output. The ^L commands in both emacs and vi modes redraw the edit line in a consistent fashion that can be used to create the next command.


ied was developed by HP.

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