[arch-general] Dynamic Titles in urxvt (bash) Without Side Effects?
grawity at gmail.com
Wed Nov 16 16:13:10 EST 2011
On 2011-11-16 15:51, Bastien Dejean wrote:
> I've added the following lines to my .bashrc:
> case "$TERM" in
> set -o functrace
> trap '[ -z "$BASH_SOURCE" ]&& printf "%b" "\e]0;$BASH_COMMAND\a"' DEBUG>& /dev/null
> (It sets the current title of the current window according to the last
> ran command.)
> But alas, it generates side effects, if I issue this:
> ls "$(ls -1 | head -1)"
> I get:
> ls: cannot access foo.bar: No such file or directory
> Strange or trivial?
First, you are using `printf` the wrong way. Such sequences as \e]0; are
supposed to be in the first argument, just like C printf():
printf "\e]0;%s\a" "$BASH_COMMAND"
Your current method causes backslash escapes to be expanded not only in
the literal \e and \a, but also in the value of $BASH_COMMAND; so, for
example, if you ran this interactively:
echo "\a is a bell"
then your current `printf` command would receive:
\e]0;echo "\a is a bell"\a
which causes the title to be set to 'echo "', and the remainder text to
be displayed normally (' is a bell"\a').
Second, your `ls` failure is caused by your `printf` output. It seems
that the DEBUG trap handler is executed for subshells as well, with the
trap handler's stdout being captured along with the actual command's
stdout. In this case, $() will return your title-setting sequence. For
echo "$(true)" > testfile
Normally, 'testfile' would be blank, but in this case...
You can sort of avoid this by redirecting the output to the proper
location -- your terminal. (I'm not sure how reliable this is.)
trap '[[ $BASH_SOURCE ]] ||
printf "\e]0;%s\a" "$BASH_COMMAND" >/dev/tty' DEBUG
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