Tag: Linux kernel

journalctl command to see kernel messages

Sometimes, there are just too many messages in journalctl output and it becomes a mystery game to search for the messages you are looking for. But luckily you do not need to use grep to find the right message. Here is example of what I had to do when I was looking for kernel messages.

journalctl _TRANSPORT=kernel
# To see all the fields, you can use the verbose mode
journalctl _TRANSPORT=kernel -o verbose

# And the filter on priority if needed to get the messages you need
journalctl _TRANSPORT=kernel PRIORITY=4

# and follow
journalctl _TRANSPORT=kernel PRIORITY=4 -f -l

tora installation on Fedora 17.

Here are the previous links on Tora:

Tora on F16

Tora on Fedora

And if you are interested in installing from source then you can always use this link:


And if you are interested in just installing it then you can always do:

rpm -ivh "http://amit-agarwal.co.in/mystuff/tora-2.1.3-1.fc17.i686.rpm"
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Short Information about loaded kernel modules

There are couple of ways you can find the information on the loadable kernel modules. All these would always involve calling lsmod to get the loaded kernel modules and then calling modinfo to get the info on the loaded modules. I will show you with examples:

$ lsmod
Module                  Size  Used by
cdc_acm                19616  0
vfat                    8744  9
fat                    41836  1 vfat

The above output is for the list of the modules loaded on the kernel.

$ modinfo vfat

filename:       /lib/modules/
author:         Gordon Chaffee
description:    VFAT filesystem support
license:        GPL
srcversion:     48F6DF1D674F0E1325466C9
depends:        fat
vermagic: SMP mod_unload 686

modinfo will list the filename, authour and other related info for the modules. So if you wanted to get the info for all the modules, then the easiest way would be to do :

lsmod|xargs modinfo

But as you can see, this will list all the info on  the module, which is not really required. So there were couple of posts on commandlinefu, that takes care of displaying only the required information, viz. filename, authour and dependency. Here are the commands:

lsmod | sed \’1d\’ | cut -d\’ \’ -f1 | xargs modinfo | egrep \’^file|^desc|^dep\’ | sed -e\’/^dep/s/$/\\n/g\’

Quite raw method where we grep the required fields and susbstitute the end with newline for the last patter \":)\"

lsmod | sed -e \’1d\’ -e \’s/\\(\\([^ ]*\\) \\)\\{1\\}.*/\\2/\’ | xargs modinfo | sed -e \’/^dep/s/$/\\n/g\’ -e \’/^file/b\’ -e \’/^desc/b\’ -e \’/^dep/b\’ -e d

Quite same as above with only exception of using one sed command rather than egrep and sed.

modinfo $(cut -d\’ \’ -f1 /proc/modules) | sed \’/^dep/s/$/\\n/; /^file\\|^desc\\|^dep/!d\’

Directly using the modinfo commands without xargs and passing the arguments with cut command and then using sed to display only the required fields.

awk \'{print $1}\’ \”/proc/modules\” | xargs modinfo | awk \’/^(filename|desc|depends)/\’

using awk to check the /proc/modules and then displaying the fields with awk