Python tools for manage system commands as replacement to bash script
The shell scripting gets to be non-maintainable code; its sintaxis is very cryptic and it’s very hard to debug. Aside all these negative point increase at the same time as the size of the program grows.
Here is where Python comes.
Whatever administrator without great knowledge about programming can built basic scripts fastly after of read the tutorial. Its sintaxis is as pseudo-code so it’s very easy to code. The basic errors –as syntax errors and exceptions– help to debug together to the error logging system implemented in logging module. In addition Python comes with an extensive standard library of useful modules which will help to speed up the development of scripts, and if you need some another module could be searched in the PyPi repository.
I had forked the Fabric project to add the files editing and something other thing but my goal is very different to that project, aside of that my changes were not added until that I deleted my forked repository (after many months).
The main tool of this package is the shell.Run() class which lets to run system commands in the same shell. It works well with pipes and pass the shell variables. It doesn’t makes pattern expansion (* ?) as in the shell but could be used shell.expand() instead.
The path of all commands used by Scripy are in the path module so it’s avoid some possible trojan. The path is right for Debian/Ubuntu systems since it’s where I can check them.
The logging is configured to write messages in YAML format since it’s more easy to parse, and using the international format for date and time.
To setup the logging, there is that run at beginning of the new script:
from scripy.setup import log log.setup(filename)
where filename is /tmp/scripy.log by default, the file where is going to be logged.
And for tear down it (after of run all script):
Then, in each module where is going to be used there is to add at the beginning:
from scripy import shell _log = shell.logger(__name__)
so it pass the module name where it’s being run. Now, can be used all methods of _log –debug(), info(), warning(), error() and critical()– to indicate the importance of a logged message.
Something that is very important in the shell script is the files editing, and Scripy makes it very easy using the edit.Edit() class. It only creates backups to files that are going to be modified, lets modify files owned by another users (since that uses sudo when the class is instancied), and has methods for append text, comment or comment out lines that start with a determined chracter, and a wrapper to sed which lets backup the file.
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