Capturing console (/dev/ttyS1) logs

Linux and Unix-Like Emergency UNIX and Linux Support
1

Hi,

I have been trying to capture console logs from the init script.
When the ramfs is mounted, i check if usb is connected , if conncted, i mount it and redirected the console logs like so:

cat & /dev/ttyS1 >> /mnt/logs.txt

I'm getting

/bin/sh : /dev/ttyS1 :permission denied

I tried changing the permission to 777, but to no avail.:confused:
I also tried sudo, and found out that our ramfs does not support this command.
The console logs are still being printed on the monitor.

Please suggest a solution.

Thanks.

2

What OS are we dealing with?

3

Are you logged in as the root user?
If so, is the output from dmesg enough?

4

This is on an embedded device with Linux 2.6.27.39-grsec.

dmesg only gives kernel logs, the logs i intent to collect come from the ramfs, before booting the kernel.

:confused:

5

there was a command called screendump similar to setterm -dump which get details from ttys

Something similar to:
Linux.com :: Everything Linux and Open Source

2 Likes
6

:rolleyes:...hmmm

That's interesting, not sure whether our ramfs had that command, but ill try that too....

Thanks.:b:

7

setterm is packaged with util-linux for RHEL, in case you need to track down the source.

I'm not sure this will meet your needs in the long-term, since that command will do only 1-time snapshots. So in the long-term, in your rc/init files, replace "echo" with "logger -s". You could implement this with a function that's included by every rc file:

echo() {
  /bin/logger -s -f /var/log/rc-init-messages -p local0.info -t "$0" -- "$*"
}

But the file must exist first, so "touch /var/log/rc-init-messages" at the top of this include file.

8

My first thought would be to try ttysnoop.

(would post more but the HTML detect script swears I'm trying to post a URL thoguh I am not)

9 
cat & /dev/ttyS1 >> /mnt/logs.txt

This is wrong. The & breaks it into two commands.

cat /dev/ttyS1 >> /mnt/logs.txt