Python and System-ish Stuff

Python's get the user's name

1 #!/usr/local/bin/python
2
3 import posix
4 import string
5
6 uid = `posix.getuid()`
7 passwd = open('/etc/passwd')
8 for line in passwd.readlines():
9      rec = string.splitfields(line, ':')
10      if rec[2] == uid:
11          print 'hello', rec[0],
12          print 'mind if we call you bruce?'
13          break
14      else:
15          print "I can't find you in /etc/passwd"

Perl's Get the User name

1 #!/usr/bin/perl -w
2
3 $user = getpwent();
4 print "hello $user, mind if I call you bruce?\n";

Using Python's FTP library

    #!/usr/local/bin/python
    from ftplib import FTP
    ftp = FTP('ftp.python.org')     # connect to host
    ftp.login()                     # login anonymous
    ftp.cwd('pub/python/doc')       # change directory
    ftp.retrlines('LIST')           # list python/doc
    F = open('python.FAQ', 'w')     # file: python.FAQ
    ftp.retrbinary('RETR FAQ', F.write, 1024)
    ftp.quit()

Using Perl's FTP Library
use Net::FTP;

                       $ftp = Net::FTP->new("some.host.name");
                       $ftp->login("anonymous","me@here.there");
                       $ftp->cwd("/pub");
                       $ftp->get("that.file");
                       $ftp->quit;
A File Comparor in Python

#!/usr/contrib/newest/bin/python
from sys import *
from os import *
from posix import *
# Define a function which "roots" a path reference, if
#     it's not already rooted.
def root_file_reference(file_reference):
        if file_reference[0] == '/':
                return file_reference
        else:
                return getcwd() + "/" + file_reference
def usage():
        print "Usage: compare_archive TARFILE DIRECTORY"
        exit(1)
if len(argv) != 3:
        usage()
source_archive = root_file_reference(argv[1])
root_of_altered_sources = root_file_reference(argv[2])
tempdir = "/tmp/comparison." + str(getpid())
report = ""
count = 0
mkdir(tempdir)
chdir(tempdir)
system("tar xf " + source_archive)
for file in popen("find . -type f -print").readlines():
                # Chop off the terminal newline.
        file = file[:-1]
        difference = popen("diff %s %s/./%s" %
                        (file, root_of_altered_sources, file)).read()
        if difference != "":
                report = report + "-------------------------------\n"
                report = report + "Modifications in " + file
                report = report + ":\n" + difference
                count = count + 1
system("rm -rf " + tempdir)
print "A total of %s sources have been changed." % count
print report

If you want to try compare_archive.py for yourself, simply install Python on a Unix host, save the source into a file named compare_archive.py, set its execution bit, and launch it from the command line. You'll see a
result that looks something like:

A total of 2 sources have been changed.
-------------------------------
Modifications in ./src/first:
1a2
> This is a new line.
-------------------------------
Modifications in ./lib/ar/mine.c:
2a3,5
> #include
> #include
> #include