Newbie: What's done by 'alog' ?

Newbie: What's done by 'alog' ?

Post by Gerald Mas » Thu, 30 Jan 1997 04:00:00



Hello all ---

My 42T with AIX 4.1.4 usually runs fine. But after I installed
IBM's "Visualization Data Explorer", the machine doesn't boot
properly. After executing /etc/rc, the machine just stopped
the boot process.

In maintanace mode, I found the something with (or close to)the
inittab must be going wrong. After some tests I tried to remove
the "alog" command from the lines of inittab listed below, and everything
went fine.
Annother machine, a 530H, is running the unchanged inittab without
any trouble.

Because my man's aren't set up yet, I didn't understand what's going
on. If anybody knows, what 'alog -tboot' and 'fbcheck' are doing in
this context, please let me know.

Thank You

Gerald Masan

Some lines of my inittab.

-This did'nt work:

rc:2:wait:/etc/rc 2>&1 | alog -tboot > /dev/console # Multi-User checks
fbcheck:2:wait:/usr/sbin/fbcheck 2>&1 | alog -tboot > /dev/console # run
/etc/firstboot

- But these did:

rc:2:wait:/etc/rc 2>&1 > /dev/console # Multi-User checks
fbcheck:2:wait:/usr/sbin/fbcheck 2>&1 > /dev/console # run /etc/firstboot

 
 
 

Newbie: What's done by 'alog' ?

Post by Matthew S. Cro » Thu, 30 Jan 1997 04:00:00




>Hello all ---

>My 42T with AIX 4.1.4 usually runs fine. But after I installed
>IBM's "Visualization Data Explorer", the machine doesn't boot
>properly. After executing /etc/rc, the machine just stopped
>the boot process.

>In maintanace mode, I found the something with (or close to)the
>inittab must be going wrong. After some tests I tried to remove
>the "alog" command from the lines of inittab listed below, and everything
>went fine.
>Annother machine, a 530H, is running the unchanged inittab without
>any trouble.

>Because my man's aren't set up yet, I didn't understand what's going
>on. If anybody knows, what 'alog -tboot' and 'fbcheck' are doing in
>this context, please let me know.

>Thank You

>Gerald Masan

I don't think that the problem would be with fbcheck.  It's just a
shell script that checks for the existence of a file, and renames it
and executes it if it exists.

I think it is more likely that the "Visualization Data Explorer"
package added something to /etc/rc.  That addition is probably
starting a process which is leaving stdout or stderr open, and
the alog command is waiting for data from the pipe that remains open.
If you can determine that something was added to /etc/rc, you could
close stdout and stderr by adding "1>&- 2>&-" to the end of the
line that was added.  That syntax closes stdout and stderr.

The alog command reads the output of commands and adds the output
to a circular log file.  An example of this is /var/adm/ras/bootlog,
which can be viewed with "alog -o -t boot".  You could also use
a text editor, but the beginning of the file contains some control
data that manages the circular log.

 
 
 

Newbie: What's done by 'alog' ?

Post by Scott L. Field » Thu, 30 Jan 1997 04:00:00


First, I would suggest reading the man pages and similar articles
that are in InfoExplorer on "alog". It is used to log the out of
some commands to a subsystem file specified within "alog".

In this case, it is used to log boot information, so if you have a
problem, you can look at the alog file to try and determine the problem.

In this case, it is not the "alog" command that is the problem, if
this is like any problems I have encountered in the past.

If this is IBM software that you installed and is causing this, then
I am MIGHTY surprised. This indicates that this software has
modified your /etc/rc file, which is really a NO-NO.

Any customized software should have its OWN startup script and have
it's own entry in /etc/inittab.

What I suspect is that entries in the /etc/rc script that have been
added are SUPPOSED to act like daemons, but they have neglected to
completely detach themselves from there parent process, etc.

If they still have any file descriptors for things like STDIO, then
when the parent completes it execution, these descriptors are kind of
passed up the chain to complete any outstanding I/O. In this case, since
the /etc/rc file has its output piped to another command, it in
essense causes the pipe to hang. Until ALL the file descriptors that
have output connections to this pipe close, then the other side of
the pipe remains open and no further progress is ever made.

With a little bit of work you can reproduce this this same situation
without "alog" OR /etc/rc.


> Hello all ---

> My 42T with AIX 4.1.4 usually runs fine. But after I installed
> IBM's "Visualization Data Explorer", the machine doesn't boot
> properly. After executing /etc/rc, the machine just stopped
> the boot process.

> In maintanace mode, I found the something with (or close to)the
> inittab must be going wrong. After some tests I tried to remove
> the "alog" command from the lines of inittab listed below, and everything
> went fine.
> Annother machine, a 530H, is running the unchanged inittab without
> any trouble.

> Because my man's aren't set up yet, I didn't understand what's going
> on. If anybody knows, what 'alog -tboot' and 'fbcheck' are doing in
> this context, please let me know.

> Thank You

> Gerald Masan

> Some lines of my inittab.

> -This did'nt work:

> rc:2:wait:/etc/rc 2>&1 | alog -tboot > /dev/console # Multi-User checks
> fbcheck:2:wait:/usr/sbin/fbcheck 2>&1 | alog -tboot > /dev/console # run
> /etc/firstboot

> - But these did:

> rc:2:wait:/etc/rc 2>&1 > /dev/console # Multi-User checks
> fbcheck:2:wait:/usr/sbin/fbcheck 2>&1 > /dev/console # run /etc/firstboot

.
.
.
.
.
.
 
 
 

1. starting off a dos-smtp-''project''

greetings!

I have a certain amount of C/c++/asm etc etc - no big deal...
not anywhere near expert but am willing to tackle this idea.

a c program running in dos that will smtp a text file
from one machine on a network to another smtp server.

the file i/o etc isnt the problem , its where to start
on the smtp networking part that i'd like some words of
guidance on.
of course - as usual , someone has already written this
program and if i can get the person who has done this
and scrounge a copy of him/her ??.....

regards all
A Learner
(aka paul kearney)

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