Try to determine whether shell is in foreground before changing directory

[GoogleCodeExporter]

Entering a ticket on the FIXME comment in r151.

Definitely a good idea to try. Maybe hard to get right, though. The w
command has been in UNIX for years and some of the man pages still aren't sure.

Original issue reported on code.google.com by bfrobin...@gmail.com on 22 Aug 2008 at 1:41

[GoogleCodeExporter]

Good call on creating a ticket.

ps can be used to find any child pids...

ps --ppid $someParentPID

Though I figured there's probably a way to read out of the process table 
directly...no?

Original comment by jpsut...@gmail.com on 22 Aug 2008 at 1:49

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That option to ps is unavailable on OS X.
I've never seen a portable C API for browsing the process table (that doesn't 
mean
there isn't one).
The best alternative (I think) is to shell out to ps using POSIX-defined 
options.

Original comment by bfrobin...@gmail.com on 22 Aug 2008 at 10:11

[GoogleCodeExporter]

This could be a bit difficult.  The BSD version of ps has a set of options 
(prefixed
with a "-" character), as does the Linux version.  The Linux version will 
accept the
BSD options but expects them to be passed without the "-" prefix.  So, we could 
use
the BSD options ("ps -j" [BSD] or "ps j" [Linux] may give us the information we
need), but we'd need to detect the particular *nix that we're running on to 
adjust
the shell command appropriately.

I did a bit of reading on Linux's ps, and it (and top) uses a library called
"libproc" that reads the data directly from the /proc filesystem.  Am I correct 
in
assuming that the BSDs (and OS X) don't have /proc to read info from?

Original comment by jpsut...@gmail.com on 23 Aug 2008 at 4:16

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BSD ps will accept the options without the leading "-".

You are correct that /proc is Linux-specific. Some BSDs ship with procfs 
support but
don't mount it by default. OS X appears to be completely out of luck.

OpenBSD has a ps that isn't setuid or setgid, with no procfs. I glanced through 
their
source and found a function kvm_getprocs() that is … surprise … available 
on OS X but
not on Linux.

Original comment by bfrobin...@gmail.com on 23 Aug 2008 at 5:45

[GoogleCodeExporter]

I've put some initial code in r188 to try using ps to detect weather the shell 
pid is 
in the foreground.  As noted in the commit log, I suspect that BSD versions of 
ps use 
a different output format, so my output parsing may not be useful for anything 
other 
than Linux.  Ben, can you test on OS X to see if this solution/hack is 
effective there 
too?

Original comment by jpsut...@gmail.com on 6 Feb 2010 at 6:10

• Changed state: Started

[GoogleCodeExporter]

I've ported my hack to the QTermWidget branch, and it seems to work on Linux.  
I 
tested by having a copy of nano running the terminal and then without while 
switching 
tabs between two docs.

Original comment by jpsut...@gmail.com on 23 Feb 2010 at 8:01

[GoogleCodeExporter]

From what I've from testing this on Linux and OS X, I think the current 
implementation works well enough for now.  Not the most robust solution in the 
world.  If anyone comes up with a better solution, patches are welcome.

Original comment by jpsut...@gmail.com on 22 Oct 2010 at 1:11

• Changed state: Fixed