But I always come up against one problem right away: word erase (Control-W). For those who don't use ^W, suppose I type something like:
% ls /backups/images/trips/arizona/2007Then I suddenly realize I want utah in 2007, not arizona. In csh, I can hit ^W twice and it erases the last two words, and I'm ready to type
u<tab>. In bash, ^W erases the whole path leaving only "ls", so it's no help here. It may seem like a small thing, but I use word erase hundreds of times a day and it's hard to give it up. Google was no help, except to tell me I wasn't the only one asking.
Then the other day I was chatting about this issue with a friend who uses zsh for that reason (zsh is much more flexible at defining key bindings) and someone asked, "Is that like Meta-Delete?"
It turned out that Alt-Backspace (like many Linux applications, bash calls the Alt key "Meta", and Linux often confuses Delete and Backspace) did exactly what I wanted. Very promising!
But Alt-Backspace is not easy to type, since it's not reachable from the "home" typing position. What I needed, now that I knew bash and readline had the function, was a way to bind it to ^W.
Bash's binding syntax is documented, though the functions available
don't seem to be. But
bind -p | grep word gave me
some useful information. It seems that \C-w was bound to
"unix-word-rubout" (that was the one I didn't want) whereas "\e\C-?"
was bound to "backward-kill-word".
("\e\C-?" is an obscure way of saying Meta-DEL: \e is escape, and
apparently bash, like emacs, treats ESC followed by a key as the same
as pressing Alt and the key simultaneously. And Control-question-mark
is the Delete character in ASCII.)
So my task was to bind \C-w to backward-kill-word. It looked like this ought to work:
... Except it didn't.
bind -p | grep w
showed that C-W was still bound to "unix-word-rubout".
It turned out that it was the terminal (stty) settings causing the problem: when the terminal's werase (word erase) character is set, readline hardwires that character to do unix-word-rubout and ignores any attempts to change it.
I found the answer in a bash bug report. The stty business was introduced in readline 5.0, but due to complaints, 5.1 was slated to add a way to override the stty settings. And happily, I had 5.2! So what was this new way override method? The posting gave no hint, but eventually I found it.
Put in your .inputrc:
set bind-tty-special-chars Off
And finally my word erase worked properly and I could use bash!
[ 16:22 Jul 17, 2007 More linux | permalink to this entry | comments ]