{"id":9584,"date":"2023-08-02T10:29:01","date_gmt":"2023-08-02T08:29:01","guid":{"rendered":"https:\/\/via-internet.de\/blog\/?p=9584"},"modified":"2023-08-10T09:30:44","modified_gmt":"2023-08-10T07:30:44","slug":"power-shell-inside-powershell","status":"publish","type":"post","link":"https:\/\/via-internet.de\/blog\/2023\/08\/02\/power-shell-inside-powershell\/","title":{"rendered":"Power Shell | Inside Powershell"},"content":{"rendered":"\n

Language<\/h2>\n\n\n\n

Switches<\/h3>\n\n\n\n

Basic Syntax<\/a><\/h4>\n\n\n\n

Let\u2019s start by taking a look at a basic switch statement.<\/p>\n\n\n\n

<\/pre>\n\n\n\n
$i = 1;<\/td><\/tr>
<\/td><\/tr>
switch ($i)<\/td><\/tr>
{<\/td><\/tr>
1 {<\/td><\/tr>
write-host “one”<\/td><\/tr>
break<\/td><\/tr>
}<\/td><\/tr>
2 {<\/td><\/tr>
write-host “two”<\/td><\/tr>
write-host “two”<\/td><\/tr>
break<\/td><\/tr>
}<\/td><\/tr>
default {<\/td><\/tr>
write-host “other”<\/td><\/tr>
break<\/td><\/tr>
}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Notice we don\u2019t use the Case: keyword at all.<\/p>\n\n\n\n
The default in PowerShell is to assume -eq is used<\/em> between your input and typed case value. This means No Case Sensitivity and No Wild Cards:<\/p>\n\n\n\n
switch(“hello”) #will match uppercase<\/td><\/tr>
{<\/td><\/tr>
“HELLO” {write-host “Uppercase” -ForegroundColor Magenta;break}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green;break}<\/td><\/tr>
}<\/td><\/tr>
<\/td><\/tr>
switch(“hello”) #will NOT match h*<\/td><\/tr>
{<\/td><\/tr>
“h*” {write-host “wildcard” -ForegroundColor Magenta;break}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green;break}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Expression Match<\/a><\/h4>\n\n\n\n
We have a long-hand switch statement that lets us use whatever we want (-eq, -gt, -le, -like, straight up boolean values, etc.)<\/p>\n\n\n\n
Psudo-code:Switch($value) { {<bool expression>} {<code>} {<bool expression>} {<code>} default {<code>} }<\/p>\n\n\n\n
Real:<\/p>\n\n\n\n
switch(“hello”) #will match uppercase<\/td><\/tr>
{<\/td><\/tr>
“HELLO” {write-host “Uppercase” -ForegroundColor Magenta;break}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green;break}<\/td><\/tr>
}<\/td><\/tr>
<\/td><\/tr>
switch(“hello”) #will NOT match h*<\/td><\/tr>
{<\/td><\/tr>
“h*” {write-host “wildcard” -ForegroundColor Magenta;break}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green;break}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Jump Statements aren\u2019t necessary<\/a><\/h4>\n\n\n\n
C# requires jump statements such as break, goto, or return. PowerShell does not!<\/p>\n\n\n\n
This is one of the coolest features in PowerShell. We actually allow for continuous case- checks.<\/p>\n\n\n\n
This means your switches can actually act more like a bunch of independent if statements. Notice the previous example, without any of the \u201cbreak statements\u201d and using a number that is less than 5, 10 and 15.<\/p>\n\n\n\n
<\/td>$num = 4<\/td><\/tr>
<\/td>Switch($num)<\/td><\/tr>
<\/td>{<\/td><\/tr>
<\/td>{$num -lt 5} {write-host “less than 5!” -ForegroundColor Magenta}<\/td><\/tr>
<\/td>{$num -lt 10} {write-host “less than 10!” -ForegroundColor green}<\/td><\/tr>
<\/td>{$num -lt 15} {write-host “less than 15!” -ForegroundColor cyan}<\/td><\/tr>
<\/td>default {write-host “greater than or equal to 15” -ForegroundColor yellow}<\/td><\/tr>
<\/td>}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Loops and $_<\/a><\/h4>\n\n\n\n
It might be common for you to take a bunch of data, do a foreach loop through it and send each value through your switch:<\/p>\n\n\n\n
$nums = 1..15<\/td><\/tr>
<\/td><\/tr>
foreach($num in $nums)<\/td><\/tr>
{<\/td><\/tr>
Switch($num)<\/td><\/tr>
{<\/td><\/tr>
{$num -lt 5} {write-host “$num is less than 5!” -ForegroundColor Magenta}<\/td><\/tr>
{$num -lt 10} {write-host “$num is less than 10!” -ForegroundColor green}<\/td><\/tr>
{$num -lt 15} {write-host “$num is less than 15!” -ForegroundColor cyan}<\/td><\/tr>
default {write-host “$num is greater than or equal to 15” -ForegroundColor yellow}<\/td><\/tr>
}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
However, PowerShell actually has a loop and $_ built right into your switch so we can chop off the foreach completely:<\/p>\n\n\n\n
$nums = 1..15<\/td><\/tr>
Switch($nums)<\/td><\/tr>
{<\/td><\/tr>
{$_ -lt 5} {write-host “$_ is less than 5!” -ForegroundColor Magenta}<\/td><\/tr>
{$_ -lt 10} {write-host “$_ is less than 10!” -ForegroundColor green}<\/td><\/tr>
{$_ -lt 15} {write-host “$_ is less than 15!” -ForegroundColor cyan}<\/td><\/tr>
default {write-host “$_ is greater than or equal to 15” -ForegroundColor yellow}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
This lets us write some really concise and convenient little code blocks. The nice thing is that if our list has 1 object it still gets handled fine, and if it\u2019s an empty collection it will just skip the whole switch!<\/p>\n\n\n\n
This, however, can lead to some confusion if you try to use \u201cbreak\u201d since our loop is also the whole switch statement:<\/p>\n\n\n\n
$nums = 1..15<\/td><\/tr>
Switch($nums)<\/td><\/tr>
{<\/td><\/tr>
{$_ -lt 5} {write-host “$_ is less than 5!” -ForegroundColor Magenta;break}<\/td><\/tr>
{$_ -lt 10} {write-host “$_ is less than 10!” -ForegroundColor green;break}<\/td><\/tr>
{$_ -lt 15} {write-host “$_ is less than 15!” -ForegroundColor cyan;break}<\/td><\/tr>
default {write-host “$_ is greater than or equal to 15” -ForegroundColor yellow}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
view raw<\/a>LoopSwitchSample3.ps1 <\/a>hosted with \u2764 by GitHub<\/a><\/p>\n\n\n\n
\n
Uh-oh, not good.<\/p>\n<\/blockquote>\n\n\n\n
We also have \u201ccontinue\u201d in PowerShell and this will stop our current iteration of our loop (or switch) so we can use the looping feature and make it like a bunch of elseifs:<\/p>\n\n\n\n
$nums = 1..15<\/td><\/tr>
Switch($nums)<\/td><\/tr>
{<\/td><\/tr>
{$_ -lt 5} {write-host “$_ is less than 5!” -ForegroundColor Magenta;continue}<\/td><\/tr>
{$_ -lt 10} {write-host “$_ is less than 10!” -ForegroundColor green;continue}<\/td><\/tr>
{$_ -lt 15} {write-host “$_ is less than 15!” -ForegroundColor cyan;continue}<\/td><\/tr>
default {write-host “$_ is greater than or equal to 15” -ForegroundColor yellow}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Shortcuts<\/a><\/h4>\n\n\n\n
In addition to the looping, we provide you a few other handy short cuts.<\/p>\n\n\n\n
If you just wanted a basic equality switch, but would want to use -ceq (case sensitivity), -like (wild cards), or -match (regex) we let you do that without writing an expression match via some parameters.<\/p>\n\n\n\n
Notice, weirdly, the parameters must come between the word \u201cswitch\u201d and the parenthesis, they won\u2019t work at the end of the parenthesis.<\/p>\n\n\n\n
switch -casesensitive (“hello”) #makes it a -ceq<\/td><\/tr>
{<\/td><\/tr>
“HELLO” {write-host “Uppercase” -ForegroundColor Magenta}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green}<\/td><\/tr>
“h*” {write-host “wildcard” -ForegroundColor Magenta}<\/td><\/tr>
}<\/td><\/tr>
<\/td><\/tr>
switch -wildcard (“hello”) #makes it a -like<\/td><\/tr>
{<\/td><\/tr>
“HELLO” {write-host “Uppercase” -ForegroundColor Magenta}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green}<\/td><\/tr>
“h*” {write-host “wildcard” -ForegroundColor Magenta}<\/td><\/tr>
}<\/td><\/tr>
<\/td><\/tr>
switch -wildcard -CaseSensitive (“hello”) #makes it a -clike<\/td><\/tr>
{<\/td><\/tr>
“HELLO” {write-host “Uppercase” -ForegroundColor Magenta}<\/td><\/tr>
“hello” {write-host “lowercase” -ForegroundColor green}<\/td><\/tr>
“h*” {write-host “wildcard” -ForegroundColor Magenta}<\/td><\/tr>
}<\/td><\/tr>
<\/td><\/tr>
switch -regex (“hello”) #makes it a -match<\/td><\/tr>
{<\/td><\/tr>
“\\w{5}” {write-host “5 characters” -ForegroundColor Magenta}<\/td><\/tr>
“\\w{6}” {write-host “6 characters” -ForegroundColor green}<\/td><\/tr>
}<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
CommandLets<\/h2>\n\n\n\n
    \n
  • Get-Alias<\/code><\/li>\n\n\n\n
  • New-Alias<\/code><\/li>\n\n\n\n
  • Set-Alias<\/code><\/li>\n\n\n\n
  • Export-Alias<\/code><\/li>\n\n\n\n
  • Import-Alias<\/code> <\/li>\n<\/ul>\n\n\n\n
    Function<\/h2>\n\n\n\n
    To see the definition of mkdir<\/code> use<\/p>\n\n\n\n
    Get-Content Function:\\mkdir<\/pre>\n","protected":false},"excerpt":{"rendered":"
    Language Switches Basic Syntax Let\u2019s start by taking a look at a basic switch statement. $i = 1; switch ($i) { 1 { write-host “one” break } 2 { write-host “two” write-host “two” break } default { write-host “other” break } } Notice we don\u2019t use the Case: keyword at all. The default in PowerShell is to assume -eq is used between your input and typed case value. This means No Case Sensitivity and No Wild Cards: switch(“hello”) #will match uppercase { “HELLO” {write-host “Uppercase” -ForegroundColor Magenta;break} “hello” {write-host “lowercase” -ForegroundColor green;break} } switch(“hello”) #will NOT match h* { “h*” {write-host “wildcard” -ForegroundColor Magenta;break} […]<\/p>\n","protected":false},"author":1,"featured_media":7170,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_crdt_document":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[102],"tags":[],"class_list":["post-9584","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-power-shell"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/posts\/9584","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/comments?post=9584"}],"version-history":[{"count":4,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/posts\/9584\/revisions"}],"predecessor-version":[{"id":9643,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/posts\/9584\/revisions\/9643"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/via-internet.de\/blog\/wp-json\/"}],"wp:attachment":[{"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/media?parent=9584"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/categories?post=9584"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/via-internet.de\/blog\/wp-json\/wp\/v2\/tags?post=9584"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}