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One man loves powershell once he failed
1. 1
One man loves PowerShell
once he failed
@gab_km
12th July, 2014
Japan PowerShell meetup #3
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Who am I?
● an engineer works in an IT services company
● use .NET mainly, love F# in private.
● be interested in Python, D language, ...
● and PowerShell!
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The topics I will tell you about
● I was bad at PowerShell, but now feel to fit it
● I found the way how to overcome to struggle
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Once upon a time...
In this tweet, I have started PowerShell 2
years ago from this time(24/Mar/2011).
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What made me hard for PowerShell
There were 2 cases I had trouble using
PowerShell:
● I seemed there are a lot of differences in
command system between PowerShell and bat.
● I could not some operations shortly in
PowerShell while I could them in good old bat.
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In these days...
I tweeted this in the spring of 2013.
It makes me improve doing in PowerShell that I
tried to write some PS1 things for a year.
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Case 1
First I wrote bat files which were executed in
booting my PC to run some useful tools like a
mailer, connect file servers or do something
convenient.
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Case 1
First I wrote bat files which were executed in
booting my PC to run some useful tools like a
mailer, connect file servers or do something
convenient.
↓
When I was learning Python, I rewrote these
booting scripts in Python, which helped me to
learn it.
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Case 1
First I wrote bat files which were executed in
booting my PC to run some useful tools like a
mailer, connect file servers or do something
convenient.
↓
When I was learning Python, I rewrote these
booting scripts in Python, which helped me to
learn it.
↓
I tried rewriting them in PowerShell again for
my learning PowerShell.
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Case 2
Chocolatey is one of the best package managers
for Windows and I like it. As I should connect
using a proxy server in my workplace, this
package manager fails installing. :-(
So I sent a pull request to achieve 'chocolatey
install' with a proxy server.
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Case 2
Chocolatey is one of the best package managers
for Windows and I like it. As I should connect
using a proxy server in my workplace, this
package manager fails installing. :-(
So I sent a pull request to achieve 'chocolatey
install' with a proxy server.
* As of 12th July, 2014, this pull request is not merged.
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Case 3
# Rename all mp4 files with “Last Write Time”
Get-ChildItem |
Where { $_.Name.StartsWith("MAKERNAME") } |
ForEach { Rename-Item $_ -newname ($(Get-ItemProperty
$_).LastWriteTime.ToString("yyyyMMdd_hhmm") + ".MP4") }
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What gave me the power to the shell
I overcame the troubles in using PowerShell
with seeing the way to do things above.
● File specification and execution
● File operation
● Pipeline
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What gave me the power to the shell
I overcame the troubles in using PowerShell
with seeing the way to do things above.
● File specification and execution
● File operation
● Pipeline
Even if you are a person who are not good at
PowerShell, the abilities to do the 3 things
above make you break down the obstacle.
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File specification and execution
PS> notitle.ps1
This is a script file named 'notitle.ps1' and
created in your current directory.
You input like above to execute it.
If it does well, your terminal shows you
“Hello, there!” as output message.
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To specify files(2)- Use '.'
PS> .notitle.ps1
Hello, there!
PS>
When you want to specify a file or a folder in
your current directory, give '.' to the head
of a relative path.
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Case - You cannot execute a file
PS> $myScript = “C:myposhnotitle.ps1”
PS> $myScript
There are some cases where you cannot execute a
file with the way we have seen.
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PS> $myScript = “C:myposhnotitle.ps1”
PS> $myScript
C:myposhnotitle.ps1
PS>
Case - You cannot execute a file
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PS> $myScript = “C:myposhnotitle.ps1”
PS> $myScript
C:myposhnotitle.ps1
PS>
Though we want to execute a file, this way
shows us only the path we set.
Case - You cannot execute a file
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To execute files(1)- Use '&'
PS> & $myScript
Hello, there!
PS>
In this case, you can pass a path to execute to
an ampersand symbol('&') and you will execute
it.
The ampersand symbol works whether there are
spaces between the symbol and the path or not.
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To execute files(2)- Use '.'
PS> . $myScript
Hello, there!
PS>
In the same case, when you use a dot symbol(.)
with a path, you will execute it.
This method is called 'Dot-Sourcing'.
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To execute files(2)- Use '.'
PS> . $myScript
Hello, there!
PS>
In the same case, when you use a dot symbol(.)
with a path, you will execute it.
This method is called 'Dot-Sourcing'.
For more details, you will find when you search
the words “dot sourcing” or ask PowerShell
wizards.( ◜◡◝ )
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File operation
● Copy
● Rename
● Delete
There were demands for files to:
Though we can use 'good old' commands from cmd,
we are born to be PowerShell geeks and we are
wannabes to use Cmdlet.
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Copy files(1)
PS> Copy-Item -Path .notitle.ps1 -Destination C:myetc
PS> ls C:myetc | where Name -eq notitle.ps1
ディレクトリ : C:myetc
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a--- 2014/07/11 23:42 31 notitle.ps1
PS>
When we want to copy files, we use Copy-Item.
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Copy files(2)
PS> Get-ChildItem C:myetc | % { $_.Name }
PS> Copy-Item -Path C:myposhn* -Destination C:myetc
PS> Get-ChildItem C:myetc | % { $_.Name }
As -Path parameter of Copy-Item understands
wildcard notations, we can use this cmdlet as
following:
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PS> Get-ChildItem C:myetc | % { $_.Name }
PS> Copy-Item -Path C:myposhn* -Destination C:myetc
PS> Get-ChildItem C:myetc | % { $_.Name }
notitle.ps1
nanimoyarukishinai.txt
PS>
Copy files(2)
As -Path parameter of Copy-Item understands
wildcard notations, we can use this cmdlet as
following:
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Rename files
PS> ls | % { $_.Name }
notitle.ps1
PS> Rename-Item -Path .notitle.ps1 -NewName foobar.ps1
PS> ls | % { $_.Name }
foobar.ps1
PS>
Use Rename-Item to rename files.
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Delete files
PS> ls | % { $_.Name }
notitle.ps1
PS> Remove-Item .notitle.ps1
PS> ls | % { $_.Name }
PS>
Use Remove-Item to delete files.
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Delete files
PS> ls | % { $_.Name }
notitle.ps1
PS> Remove-Item .notitle.ps1
PS> ls | % { $_.Name }
PS>
Use Remove-Item to delete files.
In PowerShell, cmdlets are defined by setting
their names on “Verb-Objective” rules, so we
can find them intuitively.
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Pipeline
There is a strong relationship like this:
“Associate PowerShell with pipeline,
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Pipeline
There is a strong relationship like this:
“Associate PowerShell with pipeline,
associate pipeline with F# PowerShell”
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Pipeline
in my humble opinion.
● filtering
● serial processing
There is a strong relationship like this:
“Associate PowerShell with pipeline,
associate pipeline with F# PowerShell”
When we want to use pipeline, the reason is
classified into 2 broad categories:
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Pipeline - filtering
@("hoge", "fuga", "bar") | where { $_.Length -eq 4 }
# "hoge"
# "fuga"
Filtering is one of the basis operations for
pipeline.
Returns only the elements of the collection for
which the given condition block returns $True.
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Pipeline - filtering
@("hoge", "fuga", "bar") | where { $_.Length -eq 4 }
# "hoge"
# "fuga"
Filtering is one of the basis operations for
pipeline.
Returns only the elements of the collection for
which the given condition block returns $True.
$_ is the variable for the current value in the
pipeline.
When I was one of the PowerShell newbies, I had
trouble remembering the variable and searched
again and again...
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Pipeline - serial processing(1)
@("hoge", "fuga", "bar") | foreach { $_.ToUpper() }
# "HOGE"
# "FUGA"
# “BAR”
Applies the given block for ForEach-Object to
each element of the collection.
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Pipeline - serial processing(1)
@("hoge", "fuga", "bar") | foreach { $_.ToUpper() }
# "HOGE"
# "FUGA"
# “BAR”
Applies the given block for ForEach-Object to
each element of the collection.
It is similar to the functions map, iter or
something like these in your natural functional
programming languages.
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Pipeline - serial processing(2)
@(1 .. 3) | % { $_ + 2 }
# 3
# 4
# 5
There is an useful alias for Foreach-Object:
'%' symbol.
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The topics I told you about
● I was bad at PowerShell, but now feel to fit it
● I found the way how to overcome to struggle
52. 52
The topics I told you about
● I was bad at PowerShell, but now feel to fit it
● I found the way how to overcome to struggle
● File specification and execution
● File operation
● Pipeline
53. 53
The topics I told you about
● I was bad at PowerShell, but now feel to fit it
● I found the way how to overcome to struggle
● File specification and execution
● File operation
● Pipeline
Learn You Your PowerShell
for Great Good!
