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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 12:43:23 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 12:43:23 +0000
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tree3d8907d9f67b8c8d9a407c60f5c09c947ce8a151 /examples/rlfe/README
parentInitial commit. (diff)
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Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+rlfe (ReadLine Front-End) is a "universal wrapper" around readline.
+You specify an interactive program to run (typically a shell), and
+readline is used to edit input lines.
+
+There are other such front-ends; what distinguishes this one is that
+it monitors the state of the inferior pty, and if the inferior program
+switches its terminal to raw mode, then rlfe passes your characters
+through directly. This basically means you can run your entire
+session (including bash and terminal-mode emacs) under rlfe.
+
+FEATURES
+
+* Can use all readline commands (and history) in commands that
+read input lines in "canonical mode" - even 'cat'!
+
+* Automatically switches between "readline-editing mode" and "raw mode"
+depending on the terminal mode. If the inferior program invokes
+readline itself, it will do its own line editing. (The inferior
+readline will not know about rlfe, and it will have its own history.)
+You can even run programs like 'emavs -nw' and 'vi' under rlfe.
+The goal is you could leave rlfe always on without even knowing
+about it. (We're not quite there, but it works tolerably well.)
+
+* The input line (after any prompt) is changed to bold-face.
+
+INSTALL
+
+The usual: ./configure && make && make install
+
+Note so far rlfe has only been tested on GNU Linux (Fedora Core 2)
+and Mac OS X (10.3).
+
+This assumes readline header files and libraries are in the default
+places. If not, you can create a link named readline pointing to the
+readline sources. To link with libreadline.a and libhistory.a
+you can copy or link them, or add LDFLAGS='-/path/to/readline' to
+the make command-line.
+
+USAGE
+
+Just run it. That by default runs bash. You can run some other
+command by giving it as command-line arguments.
+
+There are a few tweaks: -h allows you to name the history file,
+and -s allows you to specify its size. It default to "emacs" mode,
+but if the the environment variable EDITOR is set to "vi" that
+mode is chosen.
+
+ISSUES
+
+* The mode switching depends on the terminal mode set by the inferior
+program. Thus ssh/telnet/screen-type programs will typically be in
+raw mode, so rlfe won't be much use, even if remote programs run in
+canonical mode. The work-around is to run rlfe on the remote end.
+
+* Echo supression and prompt recognition are somewhat fragile.
+(A protocol so that the o/s tty code can reliably communicate its
+state to rlfe could solve this problem, and the previous one.)
+
+* See the intro to rlfe.c for more notes.
+
+* Assumes a VT100-compatible terminal, though that could be generalized
+if anybody cares.
+
+* Requires ncurses.
+
+* It would be useful to integrate rlfe's logic in a terminal emulator.
+That would make it easier to reposition the edit position with a mouse,
+integrate cut-and-paste with the system clipboard, and more robustly
+handle escape sequence and multi-byte characters more robustly.
+
+AUTHOR
+
+Per Bothner <per@bothner.com>
+
+LICENSE
+
+GPL.