#94: How to get output in Grid?

Hello Everyone,

Sometimes we need to see output, but we want to do some more manipulation. We tend to think what if the output can be filtered easily. With Out-gridview cmdlet it is very easy to see output in grid format.

HOW TO USE?

Write any command or set of line and at the end pipe to out-gridview.

EXAMPLE

get-process | out-gridview

Add caption

You can enter string in filter to filter out certain lines.
You have option to filter based on certain column. This can be achieved with Add Criteria button.

I hope this was quick and easy.
Happy scripting!!

#92: How to forecast the time for certain task in Powershell?

This has always been a thought since I started using Windows 98. I remember the flying files avi file which used to pretend that actual file is flying from one folder to another. It used to appear as if the correct number of files are shown. Along with that it used to show how much time it will take. All in all, it was very amusing to see when I saw for the first time. I can't forget the Windows 98 themes in Plus. They all were full loaded with so much exciting stuffs into them. Under water them was the one which used to sound at every click and when application closes, it used to sound as if water went out.

Today's tip is not about Plus theme. This is all about forecasting the time which will be required to run a command. The time might vary based on situations, but you can get some guess about time. I will use measure-command cmdlet which will show you the time required to copy a file :

$SOURCE_FILE="C:\abc.zip"
$DESTINATION_FILE="D:\abc.zip"
(Measure-Command { Copy-Item $SOURCE_FILE $DESTINATION_FILE}).totalseconds

In my case, it output as :
1.540063

My file is around 50 MB and the location is same computer, so 1.5 seconds should be correct. I run the command as well and I suppose it took this much time.

This will work for all native commands only, you cannot run some other application and try to guess the time taken. Do not try to run something on SQL Server or any other application, this is good for native applications only.


Enjoy scripting!!

#73 : How to list all files in current directory and subdirectories using Powershell?

Sometimes, we need to work with numerous files located in certain location. We might need to perform some action or read some lines with those files. When the requirement is all about reading all files in directory and sub-directories, we can simply use ls in Powershell. (Run Get-Alias ls to know which cmdlet is called in background, skipping this so that you learn something more, those who know this can avoid it ;))

Every experiment starts with a small building block, so let's run ls with recursion :

ls -recurse


You see multiple directories, but this is not useful as you don't have much option to perform any task on them.

    Directory: B:\tst

Mode                LastWriteTime     Length Name
----                -------------     ------ ----
d----         5/26/2015   6:08 AM            A
d----         5/26/2015   6:09 AM            B
-a---         5/26/2015   6:09 AM          0 file4.txt
-a---         5/26/2015   6:09 AM          0 file5.txt

    Directory: B:\tst\A

Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         5/26/2015   6:08 AM          0 file1.txt

    Directory: B:\tst\B

Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         5/26/2015   6:09 AM          0 file2.txt
-a---         5/26/2015   6:09 AM          0 file3.txt


Now, run the same command with little twist and then you will be able to much from output :

ls -Recurse | foreach { $_.FullName  }

The result is full list of files and you can perform more precise operations on them.
B:\tst\A
B:\tst\B
B:\tst\file4.txt
B:\tst\file5.txt
B:\tst\A\file1.txt
B:\tst\B\file2.txt
B:\tst\B\file3.txt

But, if you see the output above, you can see that directories are also there,  but your requirement might be only related with files or directories. So, let's get separate results for them.

List all Files recursively :
ls -Recurse | where { $_.PSIsContainer -eq $false } |  foreach { $_.FullName }

Output:
B:\tst\file4.txt
B:\tst\file5.txt
B:\tst\A\file1.txt
B:\tst\B\file2.txt
B:\tst\B\file3.txt

List all directories recursively :
ls -Recurse | where { $_.PSIsContainer -eq $true } |  foreach { $_.FullName }

Output:
B:\tst\A
B:\tst\B

So, this concludes today's tip. Always start with small example and keep trying till you get the results. Send your mails and comments and let me know if you have questions.

Enjoy!


 

#72 : How to run a program with different credential in Powershell?

There are multiple ways to achieve it. I will suggest using a Get-Credential cmdlet to get the credential and use start-process to run the script or program of your choice. You can also use invoke-command for this purpose to run commands on remote machines of you network, but the approach is not advisable when WinRM is not enabled and I don't want to make it complicated.

So, let's take a look on the script and then we will see how it runs :

$c=Get-Credential
Start-Process c:\windows\notepad.exe -Credential $c

When you run the two lines above, you see a popup which asks your credentials :

Enter credential and then you will see the notepad.exe running with that credential.

This may help you if you are making a program which requires special credentials at some point and user can enter the login and password. Good for any interactive script only. We can also save the credentials and use that. We will see that in next article, till then enjoy!

#71 : Pause a Powershell Script

Sometimes, we need to pause scripting where any asynchronous operation is in progress or we have to wait for some file to appear. In all such cases, Start-Sleep can help you achieve that. Let's take a look into syntax and then we will use the same in our example :

Syntax:
Start-Sleep -Milliseconds <int> [<CommonParameters>]
Start-Sleep [-Seconds] <int> [<CommonParameters>]


Example:
Pause the script for 5 seconds:
Start-Sleep -Seconds 5

 

#69 : Formatted output from a number with decimal using Powershell

Sometimes, we need to produce formatted output from a number with decimals. If the output has to be in a designated formatted such as till two places after decimals, we can simply format them using below. It helps specifying the precision correctly :

Below is the function to help you in setting precision till whatever places of decimal you want. If number is limited to only two digits after decimal, it will add zero as suffix, so this might help in some other cases also where you want to show result in money.

Please check the Gist below :



There are several other ways to do it, but I found it more flexible.
Enjoy scripting !!

#68 : Understanding Try-Catch-Finally Blocks in Powershell

Try-Catch-Finally is language construct introduced in Powershell v2.0. It provides option to error handling in an elegant manner. While a faulty code might stop flow of your code, Try-Catch can be used to handle some of the obvious errors. For example, if you are writing to a file and suddenly disk got full, your script will fail miserably and error could be trapped further. The script will proceed further without having finishing pervious operation correctly. In a simple language, we can say that Try-Catch gives option to handle errors during runtime without impacting the desired flow of script.

(There are so many big articles written on this subject, this article is just a jump start. My intention is not re-invent the wheel.)


Below is a simple example using this language construct :
(It will run a divide-by-error operation and cause failure. The error will be forwarded on screen)



Enjoy developing Powershell scripts!




 

#67 : Get Windows Operating System Name and Version

Sometimes, we need to know the Operating system name and version for troubleshooting and sometimes we need to run specific code for specific version. With Powershell, this is very simple.

$OS_VERSION=$(Get-WmiObject -Class Win32_OperatingSystem).Version
$OS_NAME=$(Get-WmiObject -class Win32_OperatingSystem).Caption

echo "Version : $OS_VERSION"
echo "Version : $OS_NAME"

Hope, this was simple and useful for your scripts.
Enjoy scripting!!

#66 : Formatted Date and Time Output

Mostly, in course of scripting, we need to display date and time in a qualified format. The format depends on the requirement suggested. Such as, your script log will have timestamp in a format like LOG_201505150732.log, but inside log, you timestamp might be set as 2015-05-15 07:32:03. Based on purpose, we use time in different ways.

Powershell does not require much more effort in playing with format. It is more straight forward than anything in Powershell. Simply, remember the table below to set the format :

Specifier	Type	Example	Example Output
dd	Day	{0:dd}	10
ddd	Day name	{0:ddd}	Tue
dddd	Full day name	{0:dddd}	Tuesday
f, ff, …	Second fractions	{0:fff}	932
gg, …	Era	{0:gg}	A.D.
hh	2 digit hour	{0:hh}	10
HH	2 digit hour, 24hr format	{0:HH}	22
mm	Minute 00-59	{0:mm}	38
MM	Month 01-12	{0:MM}	12
MMM	Month abbreviation	{0:MMM}	Dec
MMMM	Full month name	{0:MMMM}	December
ss	Seconds 00-59	{0:ss}	46
tt	AM or PM	{0:tt}	PM
yy	Year, 2 digits	{0:yy}	02
yyyy	Year	{0:yyyy}	2002
zz	Timezone offset, 2 digits	{0:zz}	-05
zzz	Full timezone offset	{0:zzz}	-05:00
:	Separator	{0:hh:mm:ss}	10:43:20
/	Separator	{0:dd/MM/yyyy}	10/12/2002

Using toString() function, you can do all kinds of formatting you want.

For example, if you have to get the timestamp for a log file, use below :
$FILE_NAME="ABC_$($(get-date).toString("yyyyMMddhhmmss")).log"

If you want to output the time in log file, it must be little more readable. Such as below :
$MSG="$($(get-date).toString("yyyy/MM/dd HH:mm:ss" )) : Program Started"

There are lot many experiments possible with it. This is simple, yet effective way to handle time.
Enjoy scripting!!
 

#11 : PowerGUI : A great tool!

-- Still writing this article, I would come up with full details about PowerGUI. The tool is really interesting and I may also include a video on it.

Sorry for making you wait.. Please wait for sometime...

#65 : Error-Handling with Trap

In v1.0 of Windows Powershell, there was no Try-Catch-Finally feature. We had trap construct for the same purpose. I think, Trap was a new concept as it was not there in any of the existing .NET-based languages. But Powershell v1.0 somehow had this unusual feature. In most of the old machines, there will be Powershell v1.0 and we cannot use Try-Catch blocks for those servers. So if you are writing script for all versions of Windows, there is no option left except using Trap.

Let us see the Trap example below :



The above example will call two divide statement which will end up with divide-by-zero. There are two blocks where trap is declared :
1. At script level
2. At function level

You will notice that output will call Function level when it will fail inside function block and it will call script level trap when called outside function.

Hope this simple example will make you learn this correctly. Please send me your questions and suggestion if you have any. Learning from small example is always better if you want to understand something correctly.

That's it for today! Thanks for reading today and keep reading this blog which is updated everyday.

Tool #4 : Powershell ISE with Powershell v4.0

Powershell ISE comes bundled with Powershell. The editor was useful in previous versions also, but version 4.0 comes with collapsing and expanding of functions and statement blocks. This is very important to have big functions collapsed as it avoids so much scrolling back and forth. Also, it makes script more readable if you are just reviewing someone's code. Syntax highlighting and Intellisense have already been there.

So, those who have not used it for some reasons. I would request them to give a try on this tool. If you do not see it in your newly installed Windows 2008 or 2012, you can try to add it from features.

Remarkable Features:

1. Intellisense feature
2. East of Debugging Code using Breakpoints
3. Collapsing and Expanding of blocks
4. Code and Output windows switching
5. Familiar shortcuts used in all Microsoft products such as F5 etc.

Below are some items which are missing in this version, hope Microsoft will add in future releases :
1. Script parameter passing is not possible.
2. There is no scope of writing GUI based tools.

If you find something interesting about this tool, please let me know.