Posts Tagged ‘older’

Get dmesg command kernel log report with human date / time timestamp on older Linux distributions

Friday, June 18th, 2021

how-to-get-dmesg-human-readable-timestamp-kernel-log-command-linux-logo

If you're a sysadmin you surely love to take a look at dmesg kernel log output. Usually on many Linux distributions there is a setup that dmesg keeps logging to log files /var/log/dmesg or /var/log/kern.log. But if you get some inherited old Linux servers it is quite possible that the previous machine maintainer did not enable the output of syslog to get logged in /var/log/{dmesg,kern.log,kernel.log}  or even have disabled the kernel log for some reason. Even though that in dmesg output you might find some interesting events reporting issues with Hard drives on its way to get broken / a bad / reads system processes crashing or whatever of other interesting information that could help you prevent severe servers downtimes or problems earlier but due to an old version of Linux distribution lets say Redhat 5 / Debian 6 or old CentOS / Fedora, the version of dmesg command shipped does not support the '-T' option that is present in util-linux package shipped with newer versions of  Redhat 7.X  / 8.X / SuSEs etc.  

 -T, –ctime
              Print human readable timestamps.  The timestamp could be inaccurate!

To illustrate better what I mean, here is an example from the non-human readable timestamp provided by older dmesg command

root@web-server~:# dmesg |tail -n 5
[4505913.361095] hid-generic 0003:1C4F:0002.000E: input,hidraw1: USB HID v1.10 Device [SIGMACHIP USB Keyboard] on usb-0000:00:1d.0-1.3/input1
[4558251.034024] Process accounting resumed
[4615396.191090] r8169 0000:03:00.0 eth1: Link is Down
[4615397.856950] r8169 0000:03:00.0 eth1: Link is Up – 100Mbps/Full – flow control rx/tx
[4644650.095723] Process accounting resumed

Thanksfully using below few lines of shell or perl scripts the dmesg -T  functionality could be added to the system , so you can easily get the proper timestamp out of the obscure default generated timestamp in the same manner as on newer distros.

Here is how to do with it with bash script:

#!/bin/sh paste in .bashrc and use dmesgt to get human readable timestamp
dmesg_with_human_timestamps () {
    FORMAT="%a %b %d %H:%M:%S %Y"

 

    now=$(date +%s)
    cputime_line=$(grep -m1 "\.clock" /proc/sched_debug)

    if [[ $cputime_line =~ [^0-9]*([0-9]*).* ]]; then
        cputime=$((BASH_REMATCH[1] / 1000))
    fi

    dmesg | while IFS= read -r line; do
        if [[ $line =~ ^\[\ *([0-9]+)\.[0-9]+\]\ (.*) ]]; then
            stamp=$((now-cputime+BASH_REMATCH[1]))
            echo "[$(date +”${FORMAT}” –date=@${stamp})] ${BASH_REMATCH[2]}"
        else
            echo "$line"
        fi
    done
}

Copy the script somewhere under lets say /usr/local/bin or wherever you like on the server and add into your HOME ~/.bashrc some alias like:
 

alias dmesgt=dmesg_with_timestamp.sh


You can get a copy dmesg_with_timestamp.sh of the script from here

Or you can use below few lines perl script to get the proper dmeg kernel date / time

 

#!/bin/perl
# on old Linux distros CentOS 6.0 etc. with dmesg (part of util-linux-ng-2.17.2-12.28.el6_9.2.x86_64) etc. dmesg -T not available
# workaround is little pl script below
dmesg_with_human_timestamps () {
    $(type -P dmesg) "$@" | perl -w -e 'use strict;
        my ($uptime) = do { local @ARGV="/proc/uptime";<>}; ($uptime) = ($uptime =~ /^(\d+)\./);
        foreach my $line (<>) {
            printf( ($line=~/^\[\s*(\d+)\.\d+\](.+)/) ? ( “[%s]%s\n", scalar localtime(time – $uptime + $1), $2 ) : $line )
        }'
}


Again to make use of the script put it under /usr/local/bin/check_dmesg_timestamp.pl

alias dmesgt=dmesg_with_human_timestamps

root@web-server:~# dmesgt | tail -n 20

[Sun Jun 13 15:51:49 2021] usb 2-1.3: USB disconnect, device number 9
[Sun Jun 13 15:51:50 2021] usb 2-1.3: new low-speed USB device number 10 using ehci-pci
[Sun Jun 13 15:51:50 2021] usb 2-1.3: New USB device found, idVendor=1c4f, idProduct=0002, bcdDevice= 1.10
[Sun Jun 13 15:51:50 2021] usb 2-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[Sun Jun 13 15:51:50 2021] usb 2-1.3: Product: USB Keyboard
[Sun Jun 13 15:51:50 2021] usb 2-1.3: Manufacturer: SIGMACHIP
[Sun Jun 13 15:51:50 2021] input: SIGMACHIP USB Keyboard as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.0/0003:1C4F:0002.000D/input/input25
[Sun Jun 13 15:51:50 2021] hid-generic 0003:1C4F:0002.000D: input,hidraw0: USB HID v1.10 Keyboard [SIGMACHIP USB Keyboard] on usb-0000:00:1d.0-1.3/input0
[Sun Jun 13 15:51:50 2021] input: SIGMACHIP USB Keyboard Consumer Control as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.1/0003:1C4F:0002.000E/input/input26
[Sun Jun 13 15:51:50 2021] input: SIGMACHIP USB Keyboard System Control as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.1/0003:1C4F:0002.000E/input/input27
[Sun Jun 13 15:51:50 2021] hid-generic 0003:1C4F:0002.000E: input,hidraw1: USB HID v1.10 Device [SIGMACHIP USB Keyboard] on usb-0000:00:1d.0-1.3/input1
[Mon Jun 14 06:24:08 2021] Process accounting resumed
[Mon Jun 14 22:16:33 2021] r8169 0000:03:00.0 eth1: Link is Down
[Mon Jun 14 22:16:34 2021] r8169 0000:03:00.0 eth1: Link is Up – 100Mbps/Full – flow control rx/tx

How to install binary packages on older FreeBSD releases / Install binary packages on FreeBSD 7.2

Saturday, September 29th, 2012

If you’re in a situation like, me where you run some old verison of FreeBSD and you need to install a bunch of packages let’s say GNOME Desktop environment on a host which before was used as a network router / mail server and general firewall. You will probably be surprised the usual way to install a pre-compiled BSD binaries with pkg_add -vr packagename will no longer work, i.e.:


freebsd# pkg_add -vr gnome2
Error: FTP Unable to get ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-7.2-release/Latest/gnome2.tbz: File unavailable (e.g., file not found, no access)
pkg_add: unable to fetch 'ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-7.2-release/Latest/gnome2.tbz' by URL
pkg_add: 1 package addition(s) failed

The reason why binary package fetch and install no longer work is obvious the repository link ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-7.2-release/Latest/ which was previously working no longer works.

So to install be able to install this already obsolete compiled packages what is neccessery is to explicitly change the FTP location, where the packages will be looked for with a location to a working link corresponding to your FreeBSD version. To make sure the link is working in accordance with your FreeBSD release do a search in Google and get the proper FTP link. My BSD version is RELEASE 7_2, hence after a quick look in Google, I found a binary repository containing packages for my FreeBSd under link:


ftp://ftp-archive.freebsd.org/pub/FreeBSD-Archive/ports/i386/packages-7.2-release/Latest

To change the default set binary .tgz packages repository to the newer correct one for the currently logged in user via tty or over ssh use the csh / bash PACKAGESITE variable.
Whether in csh type:


freebsd# setenv PACKAGESITE ftp://ftp-archive.freebsd.org/pub/FreeBSD-Archive/ports/i386/packages-7.2-release/Latest/

Either if you use Bourne Again (bash) shell type;


[root@freebsd ~]# export PACKAGESITE="ftp://ftp-archive.freebsd.org/pub/FreeBSD-Archive/ports/i386/packages-7.2-release/Latest/"
[root@freebsd ~]#

Just as a matter of fact it is useful to say pkg_add command uses FreeBSD (Linux wget like) fetch to download the pre-compiled binaries. In other words the PACKAGESITE var is understood by fetch command, whether it is looking for some shell exported vars 🙂
To make the new PACKAGESITE setting permanent in csh include it in /root/.cshrc:


echo 'setenv PACKAGESITE ftp://ftp-archive.freebsd.org/pub/FreeBSD-Archive/ports/i386/packages-7.2-release/Latest/' >> /root/.cshrc

If your root user is set to use bash add it to /root/.bashrc


echo 'export PACKAGESITE="ftp://ftp-archive.freebsd.org/pub/FreeBSD-Archive/ports/i386/packages-7.2-release/Latest/"' >> /root/.bashrc

That’s all now you will now be able to install pre-compiled packages via pkg_add 🙂 Enjoy!