Task: Append a record to the end of a text file
C#: using System;
using System.IO;

namespace AppendPwdRosetta
{
    class PasswordRecord
    {
        public string account, password, fullname, office, extension, homephone, email, directory, shell;
        public int UID, GID;
        public PasswordRecord(string account, string password, int UID, int GID, string fullname, string office, string extension, string homephone, 
            string email, string directory, string shell)
        {
            this.account = account; this.password = password; this.UID = UID; this.GID = GID; this.fullname = fullname; this.office = office;
            this.extension = extension; this.homephone = homephone; this.email = email; this.directory = directory; this.shell = shell;
        }
        public override string ToString()
        {
            var gecos = string.Join(",", new string[] { fullname, office, extension, homephone, email });
            return string.Join(":", new string[] { account, password, UID.ToString(), GID.ToString(), gecos, directory, shell });
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var jsmith = new PasswordRecord("jsmith", "x", 1001, 1000, "Joe Smith", "Room 1007", "(234)555-8917", "(234)555-0077", "jsmith@rosettacode.org", 
                "/home/jsmith", "/bin/bash");
            var jdoe = new PasswordRecord("jdoe", "x", 1002, 1000, "Jane Doe", "Room 1004", "(234)555-8914", "(234)555-0044", "jdoe@rosettacode.org", "/home/jdoe", 
                "/bin/bash");
            var xyz = new PasswordRecord("xyz", "x", 1003, 1000, "X Yz", "Room 1003", "(234)555-8913", "(234)555-0033", "xyz@rosettacode.org", "/home/xyz", "/bin/bash");

            
            File.WriteAllLines("passwd.txt", new string[] { jsmith.ToString(), jdoe.ToString() });

            
            File.AppendAllText("passwd.txt", xyz.ToString());

            
            string[] lines = File.ReadAllLines("passwd.txt");
            Console.WriteLine("Appended record: " + lines[2]);
        }
    }
}

Python: 



passwd_list=[
  dict(account='jsmith', password='x', UID=1001, GID=1000, 
       GECOS=dict(fullname='Joe Smith', office='Room 1007', extension='(234)555-8917',
                  homephone='(234)555-0077', email='jsmith@rosettacode.org'),
                  directory='/home/jsmith', shell='/bin/bash'),
  dict(account='jdoe', password='x', UID=1002, GID=1000,
       GECOS=dict(fullname='Jane Doe', office='Room 1004', extension='(234)555-8914',
                  homephone='(234)555-0044', email='jdoe@rosettacode.org'),
       directory='/home/jdoe', shell='/bin/bash')
]

passwd_fields="account password UID GID GECOS directory shell".split()
GECOS_fields="fullname office extension homephone email".split()

def passwd_text_repr(passwd_rec):

  passwd_rec["GECOS"]=",".join([ passwd_rec["GECOS"][field] for field in GECOS_fields])
  for field in passwd_rec: 
    if not isinstance(passwd_rec[field], str):
      passwd_rec[field]=`passwd_rec[field]`
  return ":".join([ passwd_rec[field] for field in passwd_fields ])

passwd_text=open("passwd.txt","w")
for passwd_rec in passwd_list:
  print >> passwd_text,passwd_text_repr(passwd_rec)
passwd_text.close()




passwd_text=open("passwd.txt","a+")
new_rec=dict(account='xyz', password='x', UID=1003, GID=1000,
             GECOS=dict(fullname='X Yz', office='Room 1003', extension='(234)555-8913',
                        homephone='(234)555-0033', email='xyz@rosettacode.org'),
             directory='/home/xyz', shell='/bin/bash')
print >> passwd_text,  passwd_text_repr(new_rec)
passwd_text.close()




passwd_list=list(open("passwd.txt","r"))
if "xyz" in passwd_list[-1]:
  print "Appended record:",passwd_list[-1][:-1]