Some useful Python function in daily work

It is a very good script language and I start to learn it for system integration purpose. For example, packaging automation, system administration and process monitoring.

Below are some useful functions for memo: 

1. Parameter checking:

if(len(sys.argv) != 2):
        print 'COMMAND: ERROR'
        sys.exit(1)
sys.argv[1]

2. File existence

if(os.path.exists(path) == False):
        print "ERROR: %s doesn't exist." %(path)
        sys.exit(1)

3. System Call

os.system("cd " + path + "; cvs update -d -P; cd -;")

if(subprocess.call(["tar", "-czvf", tar_package, "sys", "app"]) != 0):
        print "ERROR: fail to tar the package %s" %(tar_package)
        sys.exit(1)

It seems subprocess is preferable due to portability.



4. Print

print 'copy %s to %s' %(src, dest)

5. File Copy

shutil.copy2(src, dest)

6. Variable Declaration

dev_path = '../..'

7. Environment Variable

os.environ['PLATFORM']

8. File Path Join

os.path.join(path, os.environ['PLATFORM'], "binary")

9. Find file Name with Pattern
files = glob.glob(os.path.join(gui + '/resource/') + '*.' + format)
        for file in files:
                shutil.copy(file, target_resource)

10. File System Visit Support
It is a very good design to make it flexible to define customized operations on folder.

def remove_CVS(arg, dirname, names):
        (head, tail) = os.path.split(dirname)
        if(tail == "CVS"):
                shutil.rmtree(dirname)
                print "%s is removed. " %(dirname)

os.path.walk(package_sys, remove_CVS, "")