Software Salariman: Ruby

Showing posts with label Ruby. Show all posts

2008-08-27

What's the time?

14 quick ways to find the current time on your computer.

Cmd.exe has two built-in commands for the date and time. You have to add the /t option when calling these commands otherwise you are prompted to set the system time:

> date /t
Wed 27/08/2008
> time /t
07:42 PM

GnuWin's date command prints the date, time and time zone:

> date
Wed Aug 27 19:43:23 AUS Eastern Standard Time 2008

You can use the POSIX module in Perl to get the current date and time:

> perl -e "use POSIX; print asctime(localtime());"
Wed Aug 27 19:44:21 2008

Python has a time module similar to Perl's:

> python -c "import time; print time.asctime()"
Wed Aug 27 19:48:07 2008

PHP's time and date functions return an array, which you can dump using the print_r() function:

> php -r "print_r(get_date());"
Array
(
    [seconds] => 49
    [minutes] => 34
    [hours] => 14
    [mday] => 30
    [wday] => 6
    [mon] => 8
    [year] => 2008
    [yday] => 242
    [weekday] => Saturday
    [month] => August
    [0] => 1220070889
)

Ruby has a Time class:

> ruby -e "print Time.now"
Wed Aug 27 19:45:32 +1000 2008

PowerShell has a get-date cmdlet:

> get-date
Wednesday, 27 August 2008 7:50:13 PM

Or use the .Net System.DateTime.Now property in PowerShell:

> [System.DateTime]::Now
Thursday, 28 August 2008 9:53:21 AM

Firefox can tell you the time using the Javascript Date() object. Enter the following statement in your browser's address bar:

javascript:Date()
Wed Aug 27 2008 20:11:27 GMT+1000 (AUS Eastern Standard Time)

MSIE6 has a similar object but the output is different from Firefox's:

javascript:Date()
Thu Aug 28 10:06:59 2008

Groovy (and Java) has a java.util.Date object which defaults to the current time:

new java.util.Date()
Result: Thu Aug 28 09:58:45 EST 2008

2008-07-28

Extract Lines with Line Numbers using Gawk, Groovy, Perl, Python and Ruby

More ways to extract a block of text from a stream and prepend the line number to each line.

Below is the Gawk version. The built-in variables NR is the number of the current line and $0 is the content of the current line.

gawk "(NR >= r1 && NR <= r2) {printf("""%4d %s\n""", NR, $0)}"

The Perl and Ruby scripts are exactly the same. The built-in variable $. holds the number of the current line and $_ holds the text of the current line.

perl|ruby -ne "printf '%4d %s', $., $_ if $. >= r1 && $. <= r2"

The Groovy command line options are similar to the Perl and Ruby version, except that you have to separate -n and -e. The built-in variable count holds the number of the current line and line holds the text of the current line.

groovy -n -e "if (count >= r1 && count <= r2) out.format '%4d %s\n', count, line"

The Python version is verbose due to boilerplate code to iterate through all rows in a file:

python -c "import sys; print ''.join('%4d %s' % (r, l) for r, l in enumerate(sys.stdin) if r >= r1 and r <= r2)"

PS

2008-07-29: Added Groovy version.

2008-07-11

Extract Columns From Tabular Text - Perl and Ruby

My previous posting described using the GnuWin cut command to extract columns from tabular text data but you couldn't specify columns relative to the last column. The cut command is pretty easy to use in a command console, so if you want to overcome this limitation without too additional effort, you could write an ad-hoc script using Perl or Ruby programming languages.

A Perl solution: perl -F <delimiter> -ane "print @F[-1]".

A Ruby solution: ruby -F <delimiter> -ane "print $F[-1]".

Both Perl and Ruby have the same command line switches for splitting lines: -n makes the interpreter iterate through all lines of input for the statement specified in the -e switch, the -a switch turns on the auto-split mode and -F changes the character used to split a line.

All columns in a record are collected in the global F array. For example, you extract column two using @F[1] (Perl) or $F[1] (Ruby). To extract the last column in a record, use $F[-1].

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