Re: [Toybox] ps -T

[Rob Landley]

On 10/19/2017 06:13 PM, enh wrote
>> On 09/20/2017 05:08 PM, enh wrote:
>>> ps -T doesn't really work if you have any filters. so ps -AT is fine,
>>> but ps -p  -T only shows the main thread.
>>
>> Alas, I don't personally use threads much so basically never test this.
>>
>>> why? because slots[SLOT_pid] is "wrong" in shared_match_process (where
>>> by wrong i mean "is the tid").
>>>
>>> why? because toybox reads (say) /proc/147047/task/147058/stat and sees
>>>
>>> 147058 (CompositorTileW) S 31782 6249 6249 0 -1 1077952576 4 0 0 0 0 0
>>> 0 0 20 0 11 0 1211910244 928649216 35602 18446744073709551615
>>> 94558515900416 94558627572512 140720560858928 140506510343072
>>> 140506833892356 0 0 4098 1073827581 1 0 0 -1 31 0 0 0 0 0
>>> 94558627579744 94558633602584 9455861888 140720560866826
>>> 140720560866928 140720560866928 140720560869342 0
>>>
>>> and copies 147058 into SLOT_pid because that code no longer knows the real 
>>> pid.

I added -H to iotop, fixed the off-by-one error in screen width
truncation, set the screen width to 72, and ran "top -H -O TID,SHR" and
cursored over to the SHR column and:

  PID USER   TID [SHR]%CPU  %MEM TIME+ THREAD  PROCE
 1865 landley   1865  84M 98.1  14.8 128:47.94 thunderbird thun+
 1865 landley   1895  84M  1.8  14.8  41:53.81 SoftwareVsyncTh thun+
 1865 landley723  84M  0.0  14.8   0:00.00 StreamT~s #3048 thun+
 1865 landley  30482  84M  0.0  14.8   2:14.82 DOM Worker  thun+
 1865 landley   9488  84M  0.0  14.8   7:16.20 DOM Worker  thun+
 1865 landley  16082  84M  0.0  14.8  15:33.85 DOM Worker  thun+
 1865 landley  15523  84M  0.0  14.8   0:00.49 DOM Worker  thun+
 1865 landley  12086  84M  0.0  14.8  17:24.69 DOM Worker  thun+
 1865 landley   3838  84M  0.0  14.8  18:14.68 DOM Worker  thun+
 1865 landley   2254  84M  0.0  14.8  18:26.28 DOM Worker  thun+
 1865 landley  30746  84M  0.0  14.8  18:30.12 DOM Worker  thun+

An they all seem to think they're PID 1865, but each knows its TID?

$ ls /proc/1865/task/
10228  1865  1875  1880  1887  1893  1899  1911  1934   30482  5471
12086  1871  1876  1881  1888  1894  1903  1912  19926  30746  6316
14369  1872  1877  1882  1889  1895  1904  1921  22017  32148  9488
15523  1873  1878  1885  1891  1897  1906  1927  2254   3838   9955
16082  1874  1879  1886  1892  1898  1908  1933  2770   5469

Which seems reasonable? It's got PID, it's got TID, what do I need to
fix here?

(Aside: thunderbird really, really, really doesn't like a local
linux-kernel folder with 500k messages in it. Or a pop3 inbox going back
to 2013, which is the last time I split it. But I think what it's mad
about right now is the BUG() I hit in the vfat code which I had to fsck
away to do some work, and thus the vfat maintainer couldn't reproduce
it. I've meant to reboot ever since, it happened about 5 times before I
fixed it, emergency-zapping a filesystem each time, and the memory
menagement on this box has gone all wonky since then. I've been meaning
to reboot to replace the keyboard anyway, but 8 desktops full of windows
full of tabs takes a while to unwind...)

>>> not sure how best to fix this.
>>
>> Hmmm... Reasonably straightforward to fix,

Not necessarily straightfowrward to reproduce.

$ ps -AT
PID   TID
32667 32667 ?00:26:22 chromium-browse
32667 32668 ?00:00:00 TaskSchedulerSe
32667 32669 ?00:00:20 Chrome_ChildIOT
32667 32670 ?00:00:00 GpuMemoryThread

They're different?

$ ls /proc/32667/task/
10087  32668  32670  32672  32674  5747  5754
32667  32669  32671  32673  32697  5748

And they're reasonable?

>> but my tree has local c
>> changes in ps.c. Looks like I'm adding -m to show maximum number of
>> lines (somebody asked, it's easy enough.)
> 
> i said "no" to the single internal request we had for that when we
> switched from traditional Android top to toybox top. easy, yes, but
> not obviously useful. the original Android top only had batch mode, so
> it was a bit more useful then. but "first N" isn't an obviously
> meaningful heuristic. "field X no lower than Y" would be more
> convincing. but that's no longer as easy :-)

I can yank it again. If you wanna design a filter syntax I can probably
implement something.

I've just started poking at bc ala shell $((blah)) math syntax, and I'm
likely to make a function or two that lets you substitute in variables
(via string substitution) and do math on the result.

That said... that's not the syntax we've got in find, or in test. And ps
has:

  -o  FIELDs instead of defaults, each with optional :size and =title

I could add XXX to that, I suppose? Might take a bit of
fiddling to make room.

That said, you still couldn't implement -m with a syntax like that.
Maximum number of fields to display isn't a -o field. :)

>> And -H to iotop (which is
>> where I left off; need to come up with a test for this and haven't got
>> one. Is chrome threads or processes? 

Re: [Toybox] ps -T

[Rob Landley]

And this one was stuck in gmail's spam filter too. (Sorry for the delay,
the down arrow on my keyboard came off. I have a new keyboard but
swapping it out involves shutting this down and closing 6 desktops full
of windows full of tabs. Working on it...)

[Notices this email didn't get sent, while stopped at a McDonald's in
Oklahoma on the drive back from minneapolis to austin. Right, time to
press send...]

On 09/20/2017 05:08 PM, enh wrote:
> ps -T doesn't really work if you have any filters. so ps -AT is fine,
> but ps -p  -T only shows the main thread.

Alas, I don't personally use threads much so basically never test this.

> why? because slots[SLOT_pid] is "wrong" in shared_match_process (where
> by wrong i mean "is the tid").
> 
> why? because toybox reads (say) /proc/147047/task/147058/stat and sees
> 
> 147058 (CompositorTileW) S 31782 6249 6249 0 -1 1077952576 4 0 0 0 0 0
> 0 0 20 0 11 0 1211910244 928649216 35602 18446744073709551615
> 94558515900416 94558627572512 140720560858928 140506510343072
> 140506833892356 0 0 4098 1073827581 1 0 0 -1 31 0 0 0 0 0
> 94558627579744 94558633602584 9455861888 140720560866826
> 140720560866928 140720560866928 140720560869342 0
> 
> and copies 147058 into SLOT_pid because that code no longer knows the real 
> pid.
> 
> not sure how best to fix this.

Hmmm... Reasonably straightforward to fix, but my tree has local c
changes in ps.c. Looks like I'm adding -m to show maximum number of
lines (somebody asked, it's easy enough.) And -H to iotop (which is
where I left off; need to come up with a test for this and haven't got
one. Is chrome threads or processes? The big scott mccloud comic implied
processes, but the way google does everything implies threads, but
threads would defeat the entire VM sandboxing purpose of having each tab
in its own process...)

[Which is where I stopped doing the "this is simple, I should just fix
it before finishing the reply..." and 3 days later that part's not done
yet...]

[Rob]

[P.S. You can use two finger scrolling to replace a down arrow in
chrome, the "j" key instead of a down arrow in vi, and hit page down and
cursor back up a lot. I really should finish closing windows and shut
down so I can replace the keyboard one of these days...]
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[Toybox] ps -T

[enh]

ps -T doesn't really work if you have any filters. so ps -AT is fine,
but ps -p  -T only shows the main thread.

why? because slots[SLOT_pid] is "wrong" in shared_match_process (where
by wrong i mean "is the tid").

why? because toybox reads (say) /proc/147047/task/147058/stat and sees

147058 (CompositorTileW) S 31782 6249 6249 0 -1 1077952576 4 0 0 0 0 0
0 0 20 0 11 0 1211910244 928649216 35602 18446744073709551615
94558515900416 94558627572512 140720560858928 140506510343072
140506833892356 0 0 4098 1073827581 1 0 0 -1 31 0 0 0 0 0
94558627579744 94558633602584 9455861888 140720560866826
140720560866928 140720560866928 140720560869342 0

and copies 147058 into SLOT_pid because that code no longer knows the real pid.

not sure how best to fix this.

-- 
Elliott Hughes - http://who/enh - http://jessies.org/~enh/
Android native code/tools questions? Mail me/drop by/add me as a reviewer.
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Re: [Toybox] ps -T -o name

[enh]

On Wed, May 4, 2016 at 4:44 PM, Rob Landley  wrote:
>
>
> On 05/04/2016 03:55 PM, enh wrote:
>> seems like a bug that if you use -o but don't include 'tid', -T becomes a 
>> no-op?
>>
>> ps -A -T | wc -l
>> ps -A -T -o name | wc -l
>
> The way I implemented it,
>
> 1) If you display tid, it fetches tid.
> 2) -T changes the default fields displayed.
>
> I'm happy to implement different behavior, I'm just not familiar with
> what it should be.

i think this is new ground, but i think i can't think of a case where
you'd want -o to disable the -T you provided earlier, especially
because it's not completely unreasonable to want to list the threads
but not want the tid.

>> should this
>>
>>   dt = dirtree_read("/proc",
>> (TT.bits&(_PS_TID|_PS_TCNT)) ? get_threads : get_ps);
>>
>> be
>>
>>   dt = dirtree_read("/proc",
>> ((toys.optflags_T) || (TT.bits&(_PS_TID|_PS_TCNT))) ?
>> get_threads : get_ps);
>>
>> ?
>
> If you think that's a good idea...
>
> Committed and pushed,

thanks.

> Rob
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-- 
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Android native code/tools questions? Mail me/drop by/add me as a reviewer.
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Re: [Toybox] ps -T -o name

[Rob Landley]

On 05/04/2016 03:55 PM, enh wrote:
> seems like a bug that if you use -o but don't include 'tid', -T becomes a 
> no-op?
> 
> ps -A -T | wc -l
> ps -A -T -o name | wc -l

The way I implemented it,

1) If you display tid, it fetches tid.
2) -T changes the default fields displayed.

I'm happy to implement different behavior, I'm just not familiar with
what it should be.

> should this
> 
>   dt = dirtree_read("/proc",
> (TT.bits&(_PS_TID|_PS_TCNT)) ? get_threads : get_ps);
> 
> be
> 
>   dt = dirtree_read("/proc",
> ((toys.optflags_T) || (TT.bits&(_PS_TID|_PS_TCNT))) ?
> get_threads : get_ps);
> 
> ?

If you think that's a good idea...

Committed and pushed,

Rob
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Re: [Toybox] ps -t is cheating.

[scsijon]

On 10/22/2015 01:31 PM, Rob Landley wrote:



On 10/20/2015 12:43 AM, lamiaworks wrote:



Message: 1
Date: Mon, 19 Oct 2015 00:09:17 -0500
From: Rob Landley <r...@landley.net>
To: toybox@lists.landley.net
Subject: [Toybox] ps -t is cheating.
Message-ID: <56247afd.5050...@landley.net>
Content-Type: text/plain; charset=utf-8

So posix says this:

-t  termlist
Write information for processes associated with terminals given in
termlist. The application shall ensure that the termlist is a single
argument in the form of a  or -separated list. Terminal
identifiers shall be given in an implementation-defined format. [XSI]
[Option Start]  On XSI-conformant systems, they shall be given in one
of two forms: the device's filename (for example, tty04) or, if the
device's filename starts with tty, just the identifier following the
characters tty (for example, "04" ). [Option End]

And once again posix is somewhere back before the 1980's because
pseudo-terminals do not start with "/dev/tty". In the case of linux,
they've been /dev/pts/12 since, apparently, 1998.

The ps man page says:

-t ttylist
 Select by tty.  This selects the processes associated with the
 terminals given in ttylist.  Terminals (ttys, or screens for
 text output) can be specified in several forms: /dev/ttyS1,
 ttyS1, S1.  A plain "-" may be used to select processes not
 attached to any terminal.

Which is, once again, outright lying, because "-t 41" matches pts/41 but
-t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
instance on there.


You just brought an old nightmare back to the surface...

Try -t 05, if setup 'properly' you should get tty05 and that nowadays
should be equating to tty5's inode / character settings.


   $ ps -t 05
   error: TTY could not be found


with a little play I found that the /dev/ttyxx needs to exist first.

also to confuse, have a look at what's written at >

 http://linux.die.net/man/8/makedev

but that does bring some other nasty thoughts into it all

sorry rob

regards



Linux hasn't got a /dev/tty05. It's got a /dev/tty5. But what procps's
version of ps does (and thus what people are going to expect) is show
pts/5 for digits.

I checked in code that treats purely numeric "-t 1" as a request for
/dev/pts/1 instead of /dev/tty1. To get tty1 say "-t tty1".

I dunno about "right" behavior. I just know that posix is decades behind
what linux is actually _doing_...


My first Mainframes (1970's) had tty0 to ttyf for systems consoles I/O
ONLY, and tty00 to ttyff for user terminals.


That would be the decades behind part. :)


The problem was of course
cost for the extra user i/o cards so any tty above tty3 were often
assigned to users terminals and the relevant code 'fudged' to remove the
console level access and assign user inodes, which in turn fudged other
bits of codeet al...


Lovely.

I doubt android is providing any tty devices at all, with the possible
exception of an adb console, just pts devices to instances of the
"terminal" program. (Which isn't a default app on any of my phones yet,
but I live in hope that _someday_ I won't have to install a third party
app to get what seems to be built-in functionality.)

That said, the -t I checked in (yesterday?) is whitelisting specific
names, and if the adb terminal isn't among them I need to either stop
whitelisting (I worry that -t /dev/urandom or -t ../some/random/path
will somehow be exploitable, even though all I'm really doing is
stat-ing it) or add the new name...


Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
course /dev/ttyS0 not /dev/pts/S0.

I pine for a spec that means something,


Which means I really should _write_ the documentation I wanted to read,
yet again. Write a properly detailed "this is what toybox implements" as
an actual spec in the model of posix. Then wave it at the android and
tizen guys and have them frown and disagree with bits of it. And of
course fill in the tests; I haven't done proper ps tests yet because the
values change, from PIDs to %cpu output, but _how_ to do so is pretty
straightforward. Finite list of command line options and -o selections...

Alas, my open source stuff is not my day job. (I get to do some of it on
the clock, but the past couple week's been debugging nommu toolchains
and such...) Going as fast as I can in the time I have...

Rob



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Re: [Toybox] ps -t is cheating.

[Rob Landley]

On 10/20/2015 12:43 AM, lamiaworks wrote:
> 
>> Message: 1
>> Date: Mon, 19 Oct 2015 00:09:17 -0500
>> From: Rob Landley <r...@landley.net>
>> To: toybox@lists.landley.net
>> Subject: [Toybox] ps -t is cheating.
>> Message-ID: <56247afd.5050...@landley.net>
>> Content-Type: text/plain; charset=utf-8
>>
>> So posix says this:
>>
>> -t  termlist
>>Write information for processes associated with terminals given in
>>termlist. The application shall ensure that the termlist is a single
>>argument in the form of a  or -separated list. Terminal
>>identifiers shall be given in an implementation-defined format. [XSI]
>>[Option Start]  On XSI-conformant systems, they shall be given in one
>>of two forms: the device's filename (for example, tty04) or, if the
>>device's filename starts with tty, just the identifier following the
>>characters tty (for example, "04" ). [Option End]
>>
>> And once again posix is somewhere back before the 1980's because
>> pseudo-terminals do not start with "/dev/tty". In the case of linux,
>> they've been /dev/pts/12 since, apparently, 1998.
>>
>> The ps man page says:
>>
>>-t ttylist
>> Select by tty.  This selects the processes associated with the
>> terminals given in ttylist.  Terminals (ttys, or screens for
>> text output) can be specified in several forms: /dev/ttyS1,
>> ttyS1, S1.  A plain "-" may be used to select processes not
>> attached to any terminal.
>>
>> Which is, once again, outright lying, because "-t 41" matches pts/41 but
>> -t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
>> instance on there.
> 
> You just brought an old nightmare back to the surface...
> 
> Try -t 05, if setup 'properly' you should get tty05 and that nowadays
> should be equating to tty5's inode / character settings.

  $ ps -t 05
  error: TTY could not be found

Linux hasn't got a /dev/tty05. It's got a /dev/tty5. But what procps's
version of ps does (and thus what people are going to expect) is show
pts/5 for digits.

I checked in code that treats purely numeric "-t 1" as a request for
/dev/pts/1 instead of /dev/tty1. To get tty1 say "-t tty1".

I dunno about "right" behavior. I just know that posix is decades behind
what linux is actually _doing_...

> My first Mainframes (1970's) had tty0 to ttyf for systems consoles I/O
> ONLY, and tty00 to ttyff for user terminals.

That would be the decades behind part. :)

> The problem was of course
> cost for the extra user i/o cards so any tty above tty3 were often
> assigned to users terminals and the relevant code 'fudged' to remove the
> console level access and assign user inodes, which in turn fudged other
> bits of codeet al...

Lovely.

I doubt android is providing any tty devices at all, with the possible
exception of an adb console, just pts devices to instances of the
"terminal" program. (Which isn't a default app on any of my phones yet,
but I live in hope that _someday_ I won't have to install a third party
app to get what seems to be built-in functionality.)

That said, the -t I checked in (yesterday?) is whitelisting specific
names, and if the adb terminal isn't among them I need to either stop
whitelisting (I worry that -t /dev/urandom or -t ../some/random/path
will somehow be exploitable, even though all I'm really doing is
stat-ing it) or add the new name...

>> Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
>> which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
>> course /dev/ttyS0 not /dev/pts/S0.
>>
>> I pine for a spec that means something,

Which means I really should _write_ the documentation I wanted to read,
yet again. Write a properly detailed "this is what toybox implements" as
an actual spec in the model of posix. Then wave it at the android and
tizen guys and have them frown and disagree with bits of it. And of
course fill in the tests; I haven't done proper ps tests yet because the
values change, from PIDs to %cpu output, but _how_ to do so is pretty
straightforward. Finite list of command line options and -o selections...

Alas, my open source stuff is not my day job. (I get to do some of it on
the clock, but the past couple week's been debugging nommu toolchains
and such...) Going as fast as I can in the time I have...

Rob
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Re: [Toybox] ps -t is cheating.

[enh]

On Wed, Oct 21, 2015 at 7:31 PM, Rob Landley <r...@landley.net> wrote:
>
>
> On 10/20/2015 12:43 AM, lamiaworks wrote:
>>
>>> Message: 1
>>> Date: Mon, 19 Oct 2015 00:09:17 -0500
>>> From: Rob Landley <r...@landley.net>
>>> To: toybox@lists.landley.net
>>> Subject: [Toybox] ps -t is cheating.
>>> Message-ID: <56247afd.5050...@landley.net>
>>> Content-Type: text/plain; charset=utf-8
>>>
>>> So posix says this:
>>>
>>> -t  termlist
>>>Write information for processes associated with terminals given in
>>>termlist. The application shall ensure that the termlist is a single
>>>argument in the form of a  or -separated list. Terminal
>>>identifiers shall be given in an implementation-defined format. [XSI]
>>>[Option Start]  On XSI-conformant systems, they shall be given in one
>>>of two forms: the device's filename (for example, tty04) or, if the
>>>device's filename starts with tty, just the identifier following the
>>>characters tty (for example, "04" ). [Option End]
>>>
>>> And once again posix is somewhere back before the 1980's because
>>> pseudo-terminals do not start with "/dev/tty". In the case of linux,
>>> they've been /dev/pts/12 since, apparently, 1998.
>>>
>>> The ps man page says:
>>>
>>>-t ttylist
>>> Select by tty.  This selects the processes associated with the
>>> terminals given in ttylist.  Terminals (ttys, or screens for
>>> text output) can be specified in several forms: /dev/ttyS1,
>>> ttyS1, S1.  A plain "-" may be used to select processes not
>>> attached to any terminal.
>>>
>>> Which is, once again, outright lying, because "-t 41" matches pts/41 but
>>> -t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
>>> instance on there.
>>
>> You just brought an old nightmare back to the surface...
>>
>> Try -t 05, if setup 'properly' you should get tty05 and that nowadays
>> should be equating to tty5's inode / character settings.
>
>   $ ps -t 05
>   error: TTY could not be found
>
> Linux hasn't got a /dev/tty05. It's got a /dev/tty5. But what procps's
> version of ps does (and thus what people are going to expect) is show
> pts/5 for digits.
>
> I checked in code that treats purely numeric "-t 1" as a request for
> /dev/pts/1 instead of /dev/tty1. To get tty1 say "-t tty1".
>
> I dunno about "right" behavior. I just know that posix is decades behind
> what linux is actually _doing_...
>
>> My first Mainframes (1970's) had tty0 to ttyf for systems consoles I/O
>> ONLY, and tty00 to ttyff for user terminals.
>
> That would be the decades behind part. :)
>
>> The problem was of course
>> cost for the extra user i/o cards so any tty above tty3 were often
>> assigned to users terminals and the relevant code 'fudged' to remove the
>> console level access and assign user inodes, which in turn fudged other
>> bits of codeet al...
>
> Lovely.
>
> I doubt android is providing any tty devices at all, with the possible
> exception of an adb console, just pts devices to instances of the
> "terminal" program. (Which isn't a default app on any of my phones yet,
> but I live in hope that _someday_ I won't have to install a third party
> app to get what seems to be built-in functionality.)

adb and Terminal.app both just use /dev/pts/*, yes. but Android
devices do tend to have a surprising number of /dev/tty* devices too.
here's AOSP Nexus 9, for example:

$ adb shell ls -l "/dev/tty*"
crw-rw-rw- 1 root  root   5,   0 2015-10-20 07:31 /dev/tty
crw--- 1 root  root 253,   0 2015-10-20 07:31 /dev/ttyFIQ0
crw--- 1 root  root 238,   0 2015-10-20 07:31 /dev/ttyGS0
crw--- 1 root  root 238,   1 2015-10-20 07:31 /dev/ttyGS1
crw--- 1 root  root 238,   2 2015-10-20 07:31 /dev/ttyGS2
crw--- 1 root  root 238,   3 2015-10-20 07:31 /dev/ttyGS3
crw--- 1 root  root 238,   4 2015-10-20 07:31 /dev/ttyGS4
crw--- 1 root  root   4,  64 2015-10-20 07:31 /dev/ttyS0
crw--- 1 root  root   4,  65 2015-10-20 07:31 /dev/ttyS1
crw--- 1 root  root   4,  66 2015-10-20 07:31 /dev/ttyS2
crw--- 1 root  root   4,  67 2015-10-20 07:31 /dev/ttyS3
crw--- 1 root  root 242,   0 2015-10-20 07:31 /dev/ttyTHS0
crw-rw 1 gps   system   242,   1 2015-10-20 07:31 /dev/

Re: [Toybox] ps -t is cheating.

[Rob Landley]

On 10/19/2015 11:40 PM, Isaac Dunham wrote:
> On Mon, Oct 19, 2015 at 12:09:17AM -0500, Rob Landley wrote:
>> So posix says this:
>>
>> -t  termlist
>>   Write information for processes associated with terminals given in
>>   termlist. The application shall ensure that the termlist is a single
>>   argument in the form of a  or -separated list. Terminal
>>   identifiers shall be given in an implementation-defined format. [XSI]
>>   [Option Start]  On XSI-conformant systems, they shall be given in one
>>   of two forms: the device's filename (for example, tty04) or, if the
>>   device's filename starts with tty, just the identifier following the
>>   characters tty (for example, "04" ). [Option End]
>>
>> And once again posix is somewhere back before the 1980's because
>> pseudo-terminals do not start with "/dev/tty". In the case of linux,
>> they've been /dev/pts/12 since, apparently, 1998.
> 
> VTs start with /dev/tty, as do all interfaces that are theoretically
> serial-based. Note that 'if'.
> 
> /dev/pts is actually the result of another part of POSIX (posix_openpt & co.)

There's a kernel .config option for legacy "unix98" ptys...

>> The ps man page says:
>>
>>   -t ttylist
>>Select by tty.  This selects the processes associated with the
>>terminals given in ttylist.  Terminals (ttys, or screens for
>>text output) can be specified in several forms: /dev/ttyS1,
>>ttyS1, S1.  A plain "-" may be used to select processes not
>>attached to any terminal.
>>
>> Which is, once again, outright lying, because "-t 41" matches pts/41 but
>> -t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
>> instance on there.
>>
>> Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
>> which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
>> course /dev/ttyS0 not /dev/pts/S0.
>>
>> I pine for a spec that means something,
>>
>> Rob
>>
>> P.S.  Once again, the hard part is writing help text so ps --help can
>> explain the expected behavior succinctly. Yeah, I can do that, but how
>> do I explain it in a way that makes it sound intentional: -t ## is a pts
>> (unless maybe there isn't one? Does it fall back to tty5 if there's no
>> pts5? Hard to test right now because I've got /dev/pts/68 but only
>> /dev/tty63). Grrr. STOP TRYING TO BE CLEVER IN WAYS YOU DON'T EXPLAIN TO
>> YOUR USERS IN THE MAN PAGE. Right special case "-t number" to be pts/
>> instead of tty, accept pts/ to _not_ mean implicit tty prefix...
> 
> accept the following:
> * filenames relative to /dev

ps -t urandom

Yup, it took it.

> * filenames relative to /dev/pts

Like /dev/pts/../zero?

Oddly it doesn't seem to like symlinks. ln -s /dev/urandom 1234 neither
"ps -t 1234" or "ps -t ./1234" go through. But if I "cp -a /dev/zero"
zero and then "ps -t ./zero"...

Ah. 'mv zero zzero" then "ps -t ./zzero" and it won't find it, the
problem is it forces relative paths to be vs /dev (but doesn't stop you
from .. back out of them, so "ps -t ../$HOME/zzero" finds it.

What a mess.

> * fallback to "/dev/tty".
> No need to special case numbers.

The reference question "What does busybox do?" has the answer "Not
implement -t." (The option is in posix but not busybox...)

> This is *roughly* what procutils is doing, apart from that 'no need to
> special-case numbers' I'd assume.

Except "ps -t S0" is /dev/ttyS0...

> HTH,
> Isaac

Eh, I can work it out. It's just annoying.

Rob
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Re: [Toybox] ps -t is cheating.

[Isaac Dunham]

On Mon, Oct 19, 2015 at 12:09:17AM -0500, Rob Landley wrote:
> So posix says this:
> 
> -t  termlist
>   Write information for processes associated with terminals given in
>   termlist. The application shall ensure that the termlist is a single
>   argument in the form of a  or -separated list. Terminal
>   identifiers shall be given in an implementation-defined format. [XSI]
>   [Option Start]  On XSI-conformant systems, they shall be given in one
>   of two forms: the device's filename (for example, tty04) or, if the
>   device's filename starts with tty, just the identifier following the
>   characters tty (for example, "04" ). [Option End]
> 
> And once again posix is somewhere back before the 1980's because
> pseudo-terminals do not start with "/dev/tty". In the case of linux,
> they've been /dev/pts/12 since, apparently, 1998.

VTs start with /dev/tty, as do all interfaces that are theoretically
serial-based. Note that 'if'.

/dev/pts is actually the result of another part of POSIX (posix_openpt & co.)
 
> The ps man page says:
> 
>   -t ttylist
>Select by tty.  This selects the processes associated with the
>terminals given in ttylist.  Terminals (ttys, or screens for
>text output) can be specified in several forms: /dev/ttyS1,
>ttyS1, S1.  A plain "-" may be used to select processes not
>attached to any terminal.
> 
> Which is, once again, outright lying, because "-t 41" matches pts/41 but
> -t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
> instance on there.
> 
> Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
> which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
> course /dev/ttyS0 not /dev/pts/S0.
> 
> I pine for a spec that means something,
> 
> Rob
> 
> P.S.  Once again, the hard part is writing help text so ps --help can
> explain the expected behavior succinctly. Yeah, I can do that, but how
> do I explain it in a way that makes it sound intentional: -t ## is a pts
> (unless maybe there isn't one? Does it fall back to tty5 if there's no
> pts5? Hard to test right now because I've got /dev/pts/68 but only
> /dev/tty63). Grrr. STOP TRYING TO BE CLEVER IN WAYS YOU DON'T EXPLAIN TO
> YOUR USERS IN THE MAN PAGE. Right special case "-t number" to be pts/
> instead of tty, accept pts/ to _not_ mean implicit tty prefix...

accept the following:
* filenames relative to /dev
* filenames relative to /dev/pts
* fallback to "/dev/tty".
No need to special case numbers.

This is *roughly* what procutils is doing, apart from that 'no need to
special-case numbers' I'd assume.

HTH,
Isaac
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[Toybox] ps -t is cheating.

[Rob Landley]

So posix says this:

-t  termlist
  Write information for processes associated with terminals given in
  termlist. The application shall ensure that the termlist is a single
  argument in the form of a  or -separated list. Terminal
  identifiers shall be given in an implementation-defined format. [XSI]
  [Option Start]  On XSI-conformant systems, they shall be given in one
  of two forms: the device's filename (for example, tty04) or, if the
  device's filename starts with tty, just the identifier following the
  characters tty (for example, "04" ). [Option End]

And once again posix is somewhere back before the 1980's because
pseudo-terminals do not start with "/dev/tty". In the case of linux,
they've been /dev/pts/12 since, apparently, 1998.

The ps man page says:

  -t ttylist
   Select by tty.  This selects the processes associated with the
   terminals given in ttylist.  Terminals (ttys, or screens for
   text output) can be specified in several forms: /dev/ttyS1,
   ttyS1, S1.  A plain "-" may be used to select processes not
   attached to any terminal.

Which is, once again, outright lying, because "-t 41" matches pts/41 but
-t 5 does _not_ match tty5. You have to say "-t tty5" to get the getty
instance on there.

Meanwhile procutils "ps -t pts/41" works as does "ps -t pts/../tty5"
which is just _creepy_ and I'm not doing that bit. And -tty S0 is of
course /dev/ttyS0 not /dev/pts/S0.

I pine for a spec that means something,

Rob

P.S.  Once again, the hard part is writing help text so ps --help can
explain the expected behavior succinctly. Yeah, I can do that, but how
do I explain it in a way that makes it sound intentional: -t ## is a pts
(unless maybe there isn't one? Does it fall back to tty5 if there's no
pts5? Hard to test right now because I've got /dev/pts/68 but only
/dev/tty63). Grrr. STOP TRYING TO BE CLEVER IN WAYS YOU DON'T EXPLAIN TO
YOUR USERS IN THE MAN PAGE. Right special case "-t number" to be pts/
instead of tty, accept pts/ to _not_ mean implicit tty prefix...
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