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.
--
Jérémie Courrèges-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");
}
