Posted in Me, Tech

A script to diff files/directories on two different servers

Ok,  short one today. This is a straightforward script that simplifies comparing directories on different servers. There is no magic in it, it just rsyncs the directories to a local temp directory and runs diff against them (then deletes the directory afterwards). Mainly intended for config files, I wouldn’t recommend trying to diff gigabytes of binaries with it.

 

Posted in Programming, Tech

Convert configuration files to ansible templates

I’ve been playing around with ansible a lot lately, and I noticed that while changing stuff from “installed and configured manually” to “installed and configured by ansible” I was running into quite a few configuration files that needed to be manually turned into templates. It can be quite tedious to replace values in a configuration file with placeholders and put all those placeholders in a .yml file with default values.
Automating this is something I would have typically done in perl, but since I wanted to learn more about using regex in bash I decided to have a go at it in bash using regex and ${BASH_REMATCH}

The script takes a configuration file and spits out an ansible template, as well as the variable definitions you will need to add to your defaults/main.yml or vars/main.yml

The whole script is a bit to long to post here, but the interesting part is:

(You can download the full script here ansible_template.sh).

You can use regular expressions in a [[ ]] with =~ (e.g. if [[ “boot” =~ ^b ]]), and you can access the result of the regular expression by using ( ) to mark what parts of the result to store and access them via $BASH_REMATCH (comparable to how you would do it for other languages). Here I am parsing out anything that looks like a key=value from the configfile (with multiple possible separators) and storing the results in BASH_REMATCH[1] and BASH_REMATCH[2]

Usage of the script is pretty straightforward. you give it a prefix for the variable names (so you don’t end up with multiple roles all using a common variable name like “port”), and either a local or remote file to work with, and it spits out something like this:

There a tons of different configuration file formats out there so this script won’t work perfectly 100% of the time, but it does do quite well and reduces the manually copy&pasting to a minimum.

Posted in Internet Stuff, Security, Tech

Script to start minion in tmux

Minion is a security project from Mozilla (link). It provides a user-friendly web interface to various security scanner tools. There is a webcast demonstrating the software (link).

The software requires a few services to run, and since I like having one script take care of starting everything with the right parameters, I threw together a simple shell script that sets up a tmux session with the services started in windows with the names of the services.

Posted in Programming

How to easily add colored text output in bash scripts

Here is small snippet that can give your shell scripts some nice output: colortext.sh As with the debug.sh script, just download it to the same directory as your own script and add it with

It contains one simple function called text with the syntax text “text to be output”. Color can be red, green, yellow, blue or grey. The function does not automatically add a linebreak to the putput, so pop a \n in there if you need it. I prefer using it together with printf for clean and easy color output.

Here are some examples of how the function can be used, and below the corresponding output:

Output:

normal text
blue text, yellow text
Status of script: [ERROR]
Status of script: [OK]

Posted in Tech

bash foo

Instead of writing tons and tons of small scripts < 10 lines that all depend on each other I have the habbit of writing them as functions and throwing them into one file (easier to edit, less worries about them depending on each other). To be able to use the functions from the bash shell, just add $(basename $0) “$@” to the END of the file, and add symlinks function_name -> file.

Example:
$ ln -s foo.sh foobar

$ cat foo.sh


Posted in Tech

Bash Scripting

I’ve been doing a bit of bash scripting lately. Anyone who is interrested in bash scripting should also have a look at the “bash support” vim script http://www.vim.org/scripts/script.php?script_id=365. A fair amount of the addons are aimed at a gui usage (like gvim), but even if you are a console user like me, it adds enough features to be worth while. After using it for a few days you get addicted to the neat features, scripting in a vim without it is like typing with your nose. It’s not impossible, but you aren’t having much fun either.