Re: Finding the last foreground command in the current session
2015-06-09 19:44:44 +, Debarshi Ray: > Hey Stephane, > > On Fri, May 22, 2015 at 02:38:31PM +0100, Stephane Chazelas wrote: > > Can you not just do a tcgetpgrp() periodically > > If by "periodically" you mean "polling", then no, I don't want to do > that. I know a few terminal emulators do that, but it is bad for > power consumption and battery life. > > (We already use tcgetpgrp for checking if there is a foreground > process when the user clicks the 'x' buton.) just a few thoughts If it's for human interaction then 1/10s resolution is more than enough and tcgetpgrp is just one system call. You could always do it upon a specific escape sequence sent by PS1 (if you were going to rely on the bash-specific PROMPT_COMMAND anyway), or stop doing it 1/2 second after the last user input or pty activity if you want to avoid it when the terminal is idle. -- Stephane
Please improve documentation of "history -a"
At least in bash 4.3, the documentation for history -a says: Append the new history lines (history lines entered since the beginning of the current Bash session) to the history file. This is unfortunately misleading, since it suggests that the technique of adding "history -a" to one's PROMPT_COMMAND, as suggested here: http://heyrod.com/snippet/s/always-append-bash-history.html would append to one's history file many copies of the lines entered since the beginning of the current session. Fortunately it doesn't do that, but rather appends lines that have not yet been appended. I suggest making this clear, and also mentioning the PROMPT_COMMAND trick, as I look forward to losing far fewer useful commands from my global history by having them instantly saved, and not lost when a long-running terminal hangs and must be killed, or the machine running out of power etc. - - http://rrt.sc3d.org
[PATCH] document the -p invocation flag
--- bash-4.2/doc/bash.1.orig2015-06-10 15:09:04.0 +0200 +++ bash-4.2/doc/bash.1 2015-06-10 15:19:55.0 +0200 @@ -117,6 +117,18 @@ This option allows the positional parameters to be set when invoking an interactive shell. .TP +.B \-p +If the +.B \-p +is +.B not +present and the real and effective user or group IDs mismatch on startup, +the effective user and group IDs are set to the real ones. This behavior +can be disabled with this flag, but see +.SM +.B "INVOCATION" +for notes about setuid invocation. +.TP .B \-D A list of all double-quoted strings preceded by \fB$\fP is printed on the standard output. -- QED
Re: Bug in bash 4.3.30 with --disable-job-control
On 6/2/15 1:07 PM, Roy Keene wrote: > All, > > There is a bug of some sort in bash 4.3.30 (and likely others) when > compiled with --disable-job-control on Linux/x86_64. I can't reproduce this on RHEL 6 or Fedora 22 with bash-4.3.39. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
Re: Bug in bash 4.3.30 with --disable-job-control
On Wed, Jun 10, 2015 at 11:00:51AM -0400, Chet Ramey wrote:
> On 6/2/15 1:07 PM, Roy Keene wrote:
> > All,
> >
> > There is a bug of some sort in bash 4.3.30 (and likely others) when
> > compiled with --disable-job-control on Linux/x86_64.
>
> I can't reproduce this on RHEL 6 or Fedora 22 with bash-4.3.39.
I can reliably reproduce this in 4.3.30 and in branch `master' of the latest
git:
# Bash from `master'
dualbus@hp ...src/gnu/bash % time ./bash -ic 'until : | { ! :; }; do :; done;
echo x'
x
./bash -ic 'until : | { ! :; }; do :; done; echo x' 2.08s user 3.72s system
48% cpu 12.011 total
dualbus@hp ...src/gnu/bash % ./bash --version
GNU bash, version 4.3.39(1)-release (x86_64-unknown-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
# Bash from FTP
dualbus@hp ~/Downloads/bash-4.3.30
% time ./bash -c 'until : | { ! :; }; do :; done; echo x'
^C./bash -c 'until : | { ! :; }; do :; done; echo x' 3.10s user 18.81s
system 41% cpu 52.893 total
dualbus@hp ~/Downloads/bash-4.3.30
% time ./bash -ic 'until : | { ! :; }; do :; done; echo x'
x
./bash -ic 'until : | { ! :; }; do :; done; echo x' 1.97s user 3.53s system
52% cpu 10.427 total
dualbus@hp ~/Downloads/bash-4.3.30
% ./bash --version
GNU bash, version 4.3.30(1)-release (x86_64-unknown-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
I compiled both with:
CFLAGS='-O0 -g' ./configure --disable-job-control
Notice that it doesn't happen if you don't use the interactive mode.
All this is on GNU/Linux (debian sid):
dualbus@hp ~ % uname -a
Linux hp 3.14-2-amd64 #1 SMP Debian 3.14.15-2 (2014-08-09) x86_64 GNU/Linux
I can reproduce it on OpenBSD:
$ ./bash --version
GNU bash, version 4.3.30(1)-release (x86_64-unknown-openbsd5.6)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
$ time ./bash -ic 'until : | { ! :; }; do :; done; echo x'
x
0m0.39s real 0m0.06s user 0m0.28s system
$ time ./bash -c 'until : | { ! :; }; do :; done; echo x'
^C^C^C^C0m11.27s real 0m2.25s user 0m6.87s system
$ uname -a
OpenBSD openbsd.my.domain 5.6 GENERIC#310 amd64
And NetBSD:
[dual...@faeroes.sdf.org]$ ./bash --version
GNU bash, version 4.3.30(1)-release (x86_64-unknown-netbsd6.1.)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
[dual...@faeroes.sdf.org]$ time ./bash -ic 'until : | { ! :; }; do :; done;
echo x'
x
real0m27,27s
user0m9,72s
sys 0m12,24s
[dual...@faeroes.sdf.org]$ uname -a
NetBSD faeroes 6.1_STABLE NetBSD 6.1_STABLE (SDF6.amd64) #0: Sun Dec 21
18:11:22 UTC 2014
root@bjork:/spare/netbsd/usr/src/sys/arch/amd64/compile/SDF6.amd64 amd64
I tried digging into the issue with strace/ltrace, but I couldn't find any
pattern.
--
Eduardo Bustamante
https://dualbus.me/
Re: Bug in bash 4.3.30 with --disable-job-control
On 6/10/15 12:55 PM, Eduardo A. Bustamante López wrote: > Notice that it doesn't happen if you don't use the interactive mode. Thanks. This might be the key. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
