diff options
Diffstat (limited to 'powershell.html.markdown')
| -rw-r--r-- | powershell.html.markdown | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/powershell.html.markdown b/powershell.html.markdown index 5d21ef67..4488d94c 100644 --- a/powershell.html.markdown +++ b/powershell.html.markdown @@ -118,14 +118,15 @@ $False - 5 # => -5 2 -lt 3 -and 3 -lt 2 # => False # (-is vs. -eq) -is checks if two objects are the same type. -# -eq checks if the objects have the same values. +# -eq checks if the objects have the same values, but sometimes doesn't work +# as expected. # Note: we called '[Math]' from .NET previously without the preceeding # namespaces. We can do the same with [Collections.ArrayList] if preferred. [System.Collections.ArrayList]$a = @() # Point a at a new list $a = (1,2,3,4) $b = $a # => Point b at what a is pointing to $b -is $a.GetType() # => True, a and b equal same type -$b -eq $a # => True, a and b values are equal +$b -eq $a # => None! See below [System.Collections.Hashtable]$b = @{} # => Point a at a new hash table $b = @{'one' = 1 'two' = 2} @@ -154,6 +155,13 @@ $age = 22 "$name's name is $($name.Length) characters long." # => "Steve's name is 5 characters long." +# Strings can be compared with -eq, but are case insensitive. We can +# force with -ceq or -ieq. +"ab" -eq "ab" # => True +"ab" -eq "AB" # => True! +"ab" -ceq "AB" # => False +"ab" -ieq "AB" # => True + # Escape Characters in Powershell # Many languages use the '\', but Windows uses this character for # file paths. Powershell thus uses '`' to escape characters @@ -271,6 +279,10 @@ $array[-1..-3] # Return from last 1 to last 3 => [8, 7, 6] $array[2..-1] # Return from index 2 to last (NOT as most expect) => [3, 2, 1, 8] $array[0,2+4..6] # Return multiple ranges with the + => [1, 3, 5, 6, 7] +# -eq doesn't compare array but extract the matching elements +$array = 1,2,3,1,1 +$array -eq 1 # => 1,1,1 +($array -eq 1).Count # => 3 # Tuples are like arrays but are immutable. # To use Tuples in powershell, you must use the .NET tuple class. @@ -571,7 +583,7 @@ Get-Process | Foreach-Object ProcessName | Group-Object 1..10 | ForEach-Object { "Loop number $PSITEM" } 1..10 | Where-Object { $PSITEM -gt 5 } | ConvertTo-Json -# A notable pitfall of the pipeline is it's performance when +# A notable pitfall of the pipeline is its performance when # compared with other options. # Additionally, raw bytes are not passed through the pipeline, # so passing an image causes some issues. @@ -662,7 +674,7 @@ Powershell as a Tool: Getting Help: -```Powershell +```powershell # Find commands Get-Command about_* # alias: gcm Get-Command -Verb Add @@ -679,7 +691,7 @@ Update-Help # Run as admin If you are uncertain about your environment: -```Powershell +```powershell Get-ExecutionPolicy -List Set-ExecutionPolicy AllSigned # Execution policies include: @@ -693,7 +705,7 @@ help about_Execution_Policies # for more info $PSVersionTable ``` -```Powershell +```powershell # Calling external commands, executables, # and functions with the call operator. # Exe paths with arguments passed or containing spaces can create issues. |