Re: fooling a non-"stdin redirection accepting" app (colortail)??

[Zenaan Harkness <zen@freedbms.net>]

On 11/24/12, Sven Joachim <svenjoac@gmx.de> wrote:
> On 2012-11-24 11:36 +0100, Zenaan Harkness wrote:
>> On 11/24/12, Sven Joachim <svenjoac@gmx.de> wrote:
>>> Probably "colortail -f <(systemd-journalctl -f)" will do the trick.
>>
>> This doesn't work - I guess "<" is still a redirection to stdin or
>> something.
>
> No.

thanks for checking

>> For colortail, we need to auto-generate the corresponding filename for
>> stdin.
>
> It reports /dev/fd/63 here.  Since I did not boot with systemd as PID 1,
I get the same

> I tested with "colortail -f <(tail -f /var/log/auth.log)", however.
Yes, this works.

Here are my attempts:

$ colortail -f <(systemd-journalctl -f)
Showing user generated messages only. Users in the group 'adm' can see
all messages. Pass -q to turn this message off.
==> /dev/fd/63 <==
# no more output

$ colortail -f <(systemd-journalctl -n 2)
Showing user generated messages only. Users in the group 'adm' can see
all messages. Pass -q to turn this message off.
==> /dev/fd/63 <==
Nov 22 22:50:52 localhost xscreensaver[1763]: pam_winbind(xscreensaver:auth)...)
Nov 22 22:50:55 localhost xscreensaver[1763]: FAILED LOGIN 1 ON DISPLAY ":0"..."
# I'm guessing no more output can be got at this point

$ colortail -f <(systemd-journalctl -n 2 -f)
Showing user generated messages only. Users in the group 'adm' can see
all messages. Pass -q to turn this message off.
==> /dev/fd/63 <==
# no more output

$ colortail -f <(sudo systemd-journalctl -f)
==> /dev/fd/63 <==
# no more output

$ colortail -f <(sudo systemd-journalctl -f -n 10)
==> /dev/fd/63 <==
# no more output

$ colortail -f <(sudo systemd-journalctl -f 2>&1)
==> /dev/fd/63 <==
# no more output

$ colortail -f <(sudo systemd-journalctl)
... this produces the full journal/syslog ...
... and does not actually follow (not surprising, since no -f option
to journalctl)

$ sudo colortail -f <(sudo systemd-journalctl -f)
colortail: Failed to open file: /dev/fd/63
==> /dev/fd/63 <==
# no more output

$ sudo colortail -f <(systemd-journalctl -f)
Showing user generated messages only. Users in the group 'adm' can see
all messages. Pass -q to turn this message off.
colortail: Failed to open file: /dev/fd/63
==> /dev/fd/63 <==
# no more output


Seems a hard nut to crack... evidently systemd-journalctl does not
output in the same way as tail command...