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