Control: retitle -1 less: with -R, escape sequences are not sent to the terminal in an atomic way, yielding a race condition
On 2017-07-20 13:18:34 +0200, Vincent Lefevre wrote: > [...] > +Two-output division (10.5.5) > +mulRevToPair > [32m+Boolean functions of intervals (10.5.10) > +less > +precedes > [...] > > The "[32m" shouldn't be there, and the color of this line is > incorrect as a consequence (the escape sequence was not interpreted > as such). On 10 tests, the problem occurred 7 times. I've eventually found the cause of the problem. Thanks to xterm logging, I could see that at about the same time this line was sent to the terminal, an escape sequence was also sent to update the title of the terminal, and there was a clash between the two escape sequences. The update of the title of the terminal is done by my shell settings via a TRAPCHLD(). More precisely, when running "scd ... | m", I get: │ └─> 1594 zsh │ ├─> 19375 zsh │ │ └─> 19378 perl tdiff │ └─> 19376 less and when I type [End] in "less", tdiff terminates (it was blocking due to a full output buffer, I assume), and I get: │ └─> 1594 zsh │ └─> 19376 less The termination of process 19375 yields a SIGCHLD, trapped by the interactive shell (1594), which updates the title of the terminal. In the xterm logs, I can see: 1. ESC from "less"; 2. the escape sequence from zsh (to update the title of the terminal); 3. the end of the escape sequence from "less": "[32m". So, it seems that the issue is that "less" with the -R option does not send the escape sequence in an atomic way. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
