Or just a plain login-shell server option would be better than fiddling
with -l.
On Thu, Jun 21, 2012 at 08:18:13AM +0100, Nicholas Marriott wrote:
> I think it is correct and better to spawn login shells by default, these
> are not child shells of some shell process, they are entirely new
> shells.
>
> There is already an option to change it, default-command. I don't see a
> problem spawning two shells, shells are running, started, exited all the
> time and fork is not expensive anymore. What exactly is the issue with
> this? Do you have any boxes where this is noticeably slower than one
> shell? How much?
>
> If you can convince me it isn't a good idea and we need an option, I
> would suggest making some new prefix to default-shell like "+", so
> "+/bin/sh" doesn't run a login shell.
>
>
>
> On Thu, Jun 21, 2012 at 01:38:02AM +0200, J??r??mie Courr??ges-Anglas wrote:
> > Hi folks.
> >
> > As many of us, I'm a happy tmux user.
> > There's a small glitch, though, that I have "fixed" in my local tree,
> > and I was thinking about sharing it.
> >
> > I know that tmux spawns login shells by default, and I've read about
> > people asking how to disable that. Sadly, the solutions that can be
> > tried, currently, are:
> > - set default-shell to something appropriate. I don't know which options
> > are really available here.
> > - set default-command to "ksh" / "/bin/ksh". This leads to exec'ing
> > $SHELL to fire default-command. default-command might be set to "ksh",
> > or "/bin/ksh". If set to "exec ksh", you should save a call to
> > fork(), and an entry in the process table. The problem, imho, is that
> > it leads to exec'ing two shells instead of one. Which is (*imho*) not
> > elegant.
> > - modify the source.
> >
> > What I propose is that tmux doesn't fire a login shell unless
> > explicitely told to. tmux already has an internal login_shell variable,
> > which is used in the tmux.c/shell_exec() function, but not in
> > window.c/window_pane_spawn(). This variable seems to be properly
> > modified when tmux is called as a login shell. Shells shouldn't
> > (*imho*) be spawned as login shells by default. This could be a benefit
> > for slow machines users (as /etc/profile and ~/.profile might be
> > expensive), and matches (still imho) the least astonishment principle.
> >
> > So, I've used the following patch since a long time, but haven't tested
> > it much with tmux set as login shell. I might take a bit of time to
> > check it, but I'd prefer people that *really care* to do it. I've also
> > updated the manpage to match the behaviour change.
> >
> > This might very well break some people's setup relying on tmux
> > implicitely spawning login shells, but I honestly don't care much about
> > that. :P
> > The change could be documented in current.html and release notes for the
> > portable version.
> >
> > The following diff introduces a new auto variable and makes xasprintf()
> > unable to check the format string (with WARNINGS=Yes), but since the
> > format string it trivial, I thought it wasn't such a big problem.
> >
> > Please don't hesitate to bash me if I've missed something important. :P
> >
> > Regards.
> > --
> > J??r??mie Courr??ges-Anglas
> > GPG fingerprint: 61DB D9A0 00A4 67CF 2A90 8961 6191 8FBF 06A1 1494
> >
> > (Replaces last use of literal "tmux" by .Nm, btw)
> >
> > Index: names.c
> > ===================================================================
> > RCS file: /home/cvs/src/usr.bin/tmux/names.c,v
> > retrieving revision 1.15
> > diff -u -p -r1.15 names.c
> > --- names.c 11 Apr 2012 07:45:30 -0000 1.15
> > +++ names.c 20 Jun 2012 22:25:13 -0000
> > @@ -64,8 +64,8 @@ window_name_callback(unused int fd, unus
> > wname = default_window_name(w);
> > else {
> > /*
> > - * If tmux is using the default command, it will be a login
> > - * shell and argv[0] may have a - prefix. Remove this if it is
> > + * If tmux is using the default command, it may be a login
> > + * shell thus argv[0] could have a - prefix. Remove this if it
> > is
> > * present. Ick.
> > */
> > if (w->active->cmd != NULL && *w->active->cmd == '\0' &&
> > Index: tmux.1
> > ===================================================================
> > RCS file: /home/cvs/src/usr.bin/tmux/tmux.1,v
> > retrieving revision 1.294
> > diff -u -p -r1.294 tmux.1
> > --- tmux.1 22 May 2012 11:35:37 -0000 1.294
> > +++ tmux.1 20 Jun 2012 18:36:25 -0000
> > @@ -156,8 +156,11 @@ signal may be sent to the
> > server process to recreate it.
> > .It Fl l
> > Behave as a login shell.
> > -This flag currently has no effect and is for compatibility with other
> > shells
> > -when using tmux as a login shell.
> > +Needed for compatibility with other shells when using
> > +.Nm
> > +as a login shell. See the
> > +.Ic default-shell
> > +option.
> > .It Fl q
> > Set the
> > .Ic quiet
> > @@ -1961,7 +1964,7 @@ which may be any
> > command.
> > The default is an empty string, which instructs
> > .Nm
> > -to create a login shell using the value of the
> > +to create a shell using the value of the
> > .Ic default-shell
> > option.
> > .It Ic default-path Ar path
> > @@ -1975,7 +1978,7 @@ flag to
> > .Ic new-window .
> > .It Ic default-shell Ar path
> > Specify the default shell.
> > -This is used as the login shell for new windows when the
> > +This is used as the shell for new windows when the
> > .Ic default-command
> > option is set to empty, and must be the full path of the executable.
> > When started
> > @@ -1989,6 +1992,10 @@ or
> > This option should be configured when
> > .Nm
> > is used as a login shell.
> > +Note that if
> > +.Nm
> > +is used as a login shell, then child shell processes are also launched as
> > +login shells.
> > .It Ic default-terminal Ar terminal
> > Set the default terminal for new windows created in this session - the
> > default value of the
> > Index: window.c
> > ===================================================================
> > RCS file: /home/cvs/src/usr.bin/tmux/window.c,v
> > retrieving revision 1.80
> > diff -u -p -r1.80 window.c
> > --- window.c 28 May 2012 08:55:43 -0000 1.80
> > +++ window.c 20 Jun 2012 21:36:17 -0000
> > @@ -686,7 +686,7 @@ window_pane_spawn(struct window_pane *wp
> > {
> > struct winsize ws;
> > char *argv0, paneid[16];
> > - const char *ptr;
> > + const char *ptr, *shell_fmt;
> > struct termios tio2;
> >
> > if (wp->fd != -1) {
> > @@ -752,11 +752,12 @@ window_pane_spawn(struct window_pane *wp
> > fatal("execl failed");
> > }
> >
> > - /* No command; fork a login shell. */
> > + /* No command; fork a shell. */
> > + shell_fmt = login_shell ? "-%s" : "%s";
> > if (ptr != NULL && *(ptr + 1) != '\0')
> > - xasprintf(&argv0, "-%s", ptr + 1);
> > + xasprintf(&argv0, shell_fmt, ptr + 1);
> > else
> > - xasprintf(&argv0, "-%s", wp->shell);
> > + xasprintf(&argv0, shell_fmt, wp->shell);
> > execl(wp->shell, argv0, (char *) NULL);
> > fatal("execl failed");
> > }
