This section explains how to create a new init script for your debian based distro.
More information can be found here: https://wiki.debian.org/LSBInitScripts
Ubuntu init scripts (LSBInitScripts)
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Category Archives: script
How to remove columns from a text file
Problem
I want to remove the 1st and the 5th columns of a text file of tab separated values. The file is as follows:
HEAD1 HEAD2 HEAD3 HEAD4 HEAD5 HEAD6 1.0 -3 3.4 2 7 9 -100 -30 -1 0 -80 7 70 7 8 0 3 0 71 4.5 2.1 0.6 37 4
Convert text file between UTF-8, ISO8859, ASCII
Problem
I want to change a txt file codification from UTF-8 to ISO_8859
Solution
The iconv utility converts the encondig of characters from one codeset to another.
To show all the supported formats write:
Randomize file names in a directory
Problem
I want to add a random prefix to all the files in a directory
Solution 1:
for f in *;do mv "$f" "$RANDOM-$f" done
Solution 2:
This will replace the file name for the SHA from its name:
for f in *.mp3; do mv "$f" $(echo "$f" | sha1sum | cut -f1 -d' ').mp3 done
Minimum HTTP server with netcat
Problem
Sometimes you need to have a simple HTTP server. You want to check connectivity from other machine or whatever sinister reason you can have.
Solution
We are going to create a simple HTTP server at port 8000.
You can use the netcat command:
nc -l -p 8000 -c 'echo -e "HTTP/1.1 200 OK\n\nHello $(id -un)\nCurrent time $(date)"
Then you can go to a web browser and write load the url at the port 8000
http://localhost:8000
But this works just for one connection, after that connection you must execute again the nc command, so to accept more connections you must add a while loop:
while [ 1 ];do nc -l -p 8000 -c 'echo -e "HTTP/1.1 200 OK\n\nHello $(id -un)\nCurrent time $(date)"'; done
May be you want to display a simple html file (with no images, ajax or any other HTML element that launchs more HTTP requests) like this one:
<!DOCTYPE html> <html> <body> <h1>Example</h1> This is a simple<br/> webserver running with <b>nc</b> </body> </html>
Let’s suppose that you have your html saved in a file called index.html, then you can show it in your netcat server as follows:
while [ 1 ];do nc -l -p 8000 -c 'echo -e "HTTP/1.1 200 OK\n";cat index.html'; done
If you are not able to connect to your netcat server may be you have activated iptables, take a look writing as root:
iptables -L
If you want to remove the iptables that can be blocking this requests write the following commands as root:
iptables -F iptables -X iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT
Unique visitors in apache logs
Problem
I have an apache webserver connected to internet and I want to know the number of unique visitors that it receives.
I want to differentiate the visitors by its source IP address.
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Replace content of multiple files
Problem
Imagine you have some misspelled words in some documents:
$ grep Intalac * file02.html: <h2 align="left"><a name="ubuntu"></a>Intalación en Ubuntu 12.10<img src="img/009-ubuntu.png" width="62" height="59"></h2> file04.html: <h3 align="left">Intalación en Ubuntu <img src="img/009-ubuntu.png" width="62" height="59"></h3> file04.html: <h3 align="left">Intalación en Ubuntu <img src="img/009-ubuntu.png" width="62" height="59"></h3>
In this case you want to change a word in all the documents.
Solution
You can use sed with vi commands:
sed -i 's/<original>/<replaced>/g'
In this case we can solve the problem with
sed -i 's/Intal/Instal/g' *.html
