ssh authorized keys – limit ssh session to custom command

2015-03-04 1 min read Learning Linux

If you want a ssh key to be able to run a custom command only and nothing beyond that, then you can use the “command” option in the authorized_keys file of ssh.

For example, to limit user to run only top command with a key, you can add the key like this:

echo 'command="/usr/bin/top" ssh-rsa ' >>~/.ssh/authorized_keys

script to get hard disk health in fedora/ubuntu

2014-12-01 2 min read Fedora Learning Linux

First, put this in a script.

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#!/bin/bash

#Change as appropriate
HDD=sda

export sub="SmartCtl data for HDD"
echo 'To: &lt;Your Email&gt;
Sub: [Cron] $sub
MIME-Version: 1.0
Content-Type: text/html
Content-Disposition: inline

&lt;html&gt;&lt;pre&gt;'


echo '&lt;style&gt;

hr {
    display: block;
    height: 1px;
    border: 0;
    border-top: 1px solid #ccc;
    margin: 1em 0;
    padding: 0;
}
&lt;/style&gt;
'

echo '&lt;h2&gt;Errors on HDD:&lt;/h2&gt;'
echo '&lt;hr&gt;'
sudo smartctl -l error  /dev/$HDD
echo '&lt;h2&gt;Health of HDD:&lt;/h2&gt;'
echo '&lt;hr&gt;'
sudo smartctl -H  /dev/$HDD

echo '&lt;h2&gt;Detailed info&lt;/h2&gt;'
echo '&lt;hr&gt;'
sudo smartctl -a -d ata /dev/$HDD

echo '&lt;h2&gt;Journalctl output for smartd&lt;/h2&gt;'
echo '&lt;hr&gt;'

if [[ -f /etc/fedora-release ]]
then
journalctl -x --show-cursor -u smartd --since=yesterday
else
#This is for Ubuntu.. still using dmesg

dmesg -T -l err,crit,alert,emerg

fi


echo '&lt;h2&gt;All Details&lt;/h2&gt;'
echo '&lt;hr&gt;'

sudo smartctl --xall /dev/$HDD


echo "Thanks for using Amit Agarwal's script"
echo '&lt;/pre&gt;&lt;/html&gt;'

and then put this in cron:

Apache server-status – better looking

2014-08-18 2 min read Linux

Apache provides a module to see the server-status. However the page is not too good looking. So, if you want to see a better looking information page, then you can download :

http://sourceforge.net/projects/pimpapachestat/

More details from the readme file of the project:

REQUIREMENTS

On the system you want to install the pimped Apache status:
– any webserver with php 5 (with curl; no database is needed)

On all webservers you want to monitor:
– apache 2.x
– installed module mod_status and ExtendedStatus On
– permission for the monitoring server to request the the
alias /server-status (see below)

And tehn for installation:

rfc2html – php script to view rfc with index and links.

2014-07-21 2 min read Learning Linux

If you have to keep viewing RFC’s and you miss index and links in RFC while viewing rfc, then you should check-out rfc2html. It is scrtip that takes plain text rfc and converts it to html.

You can get the original code from sourceforge.

However, I found some small issues with the script and have sent a mail to the authour about the same. In the meantime, you can use the diff below to fix the issue’s or download this diff file rfc2html.diff and apply the diff:

inotify -watch for file to change

2014-01-28 1 min read Learning Linux

Here is a simple command for you. It uses inotify tools. So first you need to install :

sudo yum install inotify-tools

and then you can try something like this:

while true; 
do 
inotifywait -r -e modify --exclude=".swp" . && make; 
done

Here, once the file changes, we are running make, but you can do anything you want.

more clients for mpd.

2013-12-26 1 min read Fedora Linux

Here are some more clients that you can use with mpd.

sudo yum install mpd mpc qmpdclient.x86_64 gmpc.x86_64 sonata.x86_64

mpd is ::

Music Player Daemon (MPD) is a flexible, powerful, server-side application for
playing music. Through plugins and libraries it can play a variety of sound
files (e.g., OGG, MP3, FLAC, AAC, WAV) and can be controlled remotely via its
network protocol. It can be used as a desktop music player, but is also great
for streaming music to a stereo system over a local network. There are many
GUI and command-line applications to choose from that act as a front-end for
browsing and playing your MPD music collection.
Continue reading

Fix typescript files generated with script command

2013-12-18 1 min read Learning Linux

Generally quite a lot of us would have used the script command. This generates the logs for the session. But the problem with the logs is that it contains a lot of un-readable characters. These characters are mostly from the color codes, and as such can be removed very easily with a single command:

cat typescript | 
 perl -pe 's/e([^[]]|[.*.*?[a-zA-Z]|].*?a)//g' | col -b > typescript-processed

This assumes the input log file is named as typescript and the output is kept as typescript-processed. You can change the names as required.

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