I was writing a basic guessing game and when I tried to take user input I was
getting the following:

Code:

guess = input()
d

Error:

Traceback (most recent call last):
  File "", line 1, in 
  File "", line 1, in 
NameError: name 'd' is not defined

The problem is actually with the version of Python that I was using. If you
are using Python 2.x, you need to use the raw_input() function. And with 3.x
you can use the input() function.

Tags: Python, scripting

There comes a time when you are writing a program and you need to branch based on input to a program.
This is the format of the if/else statement in Python.

if <some true/false statement> :
  <some statements that run if the if statement is true>
else:
  <some other statements that run if the if statement are false>

There may be times when you have more than one value set to test against. In that case you can write a many if/else
statements but you can chain the if/else statements with an elif. So the chain becomes if/elif/else.

if x < 5:
  <some statements that run if the if statement is true>
elif x > 5 and x < 10:
  <some statements that run if the elif statement is true>
else:
  <if none of the if checks are true, run the statements in the else case.>

Tags: Python, scripting

I was toying with a prime number finder and was creating a set of if/else statements for a horribly failed attempt
and wanted to skip to the next number on any of the if statements that were true. I didn’t want to put an empty print
statement as that would disrupt the output I was expecting from the program. I found the pass statement.
Here is an example from my not very successful attempt at finding primes:

if inp > 2 and inp % 2 == 0:
  pass
elif inp > 3 and inp % 3 == 0:
  pass
elif inp > 7 and inp % 7 == 0:
  pass
elif inp > 9 and inp % 9 == 0:
  pass
else:
  print inp, " is a prime"

Yes, this does not accurately find the primes, but it would skip any number that is divisible by 2,3,5,7, or 9. And
anything that does not match this will be listed as a prime, this is incorrect and would be made to add new elif
statements as each prime was found.

Tags: Python, scripting

The other day I had a requirement to fill in a date value while creating an entity in ClearQuest. The field that was required was a date and was formatted as “mm/dd/yyyy hh:MM::SS AM|PM”. I used the localtime function to return the date and used sprintf to format the date to the proper output.
The reason I used sprintf was that for hours, months and days less 10 the output was 1 digit instead of two and the input was not allowed. The %02d states that the digits used will be a minumum of 2 in this case.

Here is the sample program I wrote to test the expected output:

 my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime;

# formatted just by concatenating output
my $datestring = $mon . "/" . $mday . "/" . $year . "  " . $hour . ":" . $min.
":" . $sec  ;

# formatted using sprintf to ensure proper digit counts are output
my $datestring2 = sprintf("%02d/%02d/%04d %d:%02d:%02d %s",$mon,$mday,1900 +$yea
r,$hour,$min,$sec, $hour >= 12? "PM" : "AM");

 print $datestring;
  print $datestring2;

Tags: perl, scripting

I was writing a batch file the other day and needed to change the argumets to a command based on if the user had specified his password on the command line.

SET PASS=somepassword
: or
:SET PASS=
if x%PASS%= X (
  SET PASSARG=--password somepassword
) else
(
  SET PASSARG=
)

commandtorun %PASSARG%

Now if the user comments out his password, the script will make the PASSARG environment variable be empty or if they set a password the passarg variable will be filled in.

Tags: DOS, scripting

In each language that I have learned I have found it useful to know how to process command line arguments and here is a simple framework that I use for Java. I usually wrap the java command line in a bat or shell file to make it easier to run so that the user does not have to worry about classpath or path issues.

The following is the basic code to handle the command line arguments.

class CmdArgs
{

  public static void main(String[] args)
  {
      int argsize = args.length;
      String curarg;

      if (argsize > 0 )
      {

      }

      for(int i = 0; i < argsize; i++)
      {
          if (args[i].equals("--host")
          {
             args++;
             host = args[i];
           }
          else if (args[i].equals("--debug")
          {
               debug = 1;
          }
          else
          {
              System.out.println("Unknown option: " + args[i]);
              System.exit(1);
          }
       }

   }
}

The bat file for Dos/Windows might look like this:

@echo off

java -cp c:\javabin;somejar.jar  com.etechtips.CmdArgs %*

The shell based file might look like:

java -cp /home/ecdown/javabin:somejar.jar com.etechtips.CmdArgs $*

Tags: Java, Scripts

I use find and grep quite a bit. I found that I was regularly searching for strings in file and was typing commands like:

find . -exec grep "somestring" {} \; --print

This find command will search from the current directory and for each file will run grep on it and if it finds a matching string, it will print the string and then the filename. So I took this and moved it into a script.

#!/bin/sh

if [ $# -lt 1 ]; then
  echo 1>&2 Usage: $0 ""
  exit 127
fi
icase=
search=

while [ $# -ge 1 ]; do
  case $1 in
     -i) icase=$1;;
      *) search=$1 ;;
  esac
  shift
done

find . -type f -print0 | xargs -0 grep $icase $search

This allows me to run a command such as

efind -i Super

This command will search all files starting from the current directory and recurse directories and the “-i” will tell it to ignore case.

Tags: scripting

I regularly have to process Comma Seperated Value or CSV files, usually for user lists. So the following perl code is a framework for processing a file line by line.

#!/usr/bin/perl
use strict;
my $line;

open(FILEIN, "filename.txt");

while(<FILEIN>)
{
  chomp();
  $line = $_;
  # Process $line for data
  # Example seperating line by commas:
  my ($username,$firstname,$lastname,$email) = split(/,/,$line);
}

close(FILEIN);

Tags: perl, scripting

Here are some basics about Perl hashes that can be helpful to be used when an you need to associate a label with some value such as for names and telephone numbers or account numbers with amounts owed.

Create a hash variable.

my %hashvar;

Create a hash reference

my $refhash = {};

Add a value to a hash variable.

$hashvar{'somekey'} = 'someval';

Add a value to a hash reference.

$hashref->{'somekey'} = 'someotherval';

Access a value in a hash.

print $hashvar{'somekey'};

Access a value in a hash reference.

print $hashref->{'somekey}';

Access all Keys in a hash variable.
foreach my $k (keys(%hashvar))
{
print $hashvar{$k};
}

Access all Keys in a hash reference.

foreach my $k (keys(%$hashref))
{
  print $k . "\n";
}

Access all Keys and values in a hash.

while (my ($key,$value) = each %hashvar)
{
  print "Key: " . $key . " has value:" . $value . "\n";
}

Access all Keys and values in a hash.

while (my ($key,$value) = each %$refhash)
{
  print "Key: " . $key . " has value:" . $value . "\n";
}

Assigning multiple values to a hash

%hasvar = (
  'test2' => 'myval',
  'test3' => 'myval3'
);

Note: This will clear the existing hash.

Delete a value from a hash

delete $hashvar{'key1'};

Delete a value from a hash reference.

delete $hashref->{'key1'};

Tags: hash, perl, scripting, Utilities

I use perl arrays in some of my programs, and just started to look at the regular things that I do with these arrays and thought it would be useful to keep a list of frequently used items.

Create a variable specified as an array.

my @vararray

Add an item to the beginning of an array

unshift (@vararray, "File2");

Add an item to the end of an array

push (@vararray, "File1");

Remove an item from the beginning of an array

my $var = shift(@array);

Remove an item from the end of an array

pop(@array)

Clear an array

@vararray = ();

Address an item in an array

print $vararray[0] ;

Get the size of an array

my $arraysize = @array;

Remove an item based on the index

delete @vararray[1];

Iterate over an array

foreach my $var (@vararay)
{
  print "$var \n";
}

# or
my $size = @vararray;
my $i;
for ($i = 0 ; $i < @size; $i++)
{
  print "$vararray[$i]\n";
}

Tags: array, perl, scripting