The following useful information is primarily taken from the Windows PowerShell Language Quick Reference (QuadFold.rtf) documentation.
If / Elseif / Else
When executed on the command line, the closing brace must be on the same line as the preceding keyword.
1if (condition) {...}
2elseif (condition) {...}
3else {...}</blockquote>
Switch
The variable $_ is available in the script. $_ represents the current value being evaluated. If an array is used in switch, each element of the array is tested.
Example:
1$var = "word1","word2","word3"
2switch -regex ($var) {
3 "word1" {"Multi-match Exact " + $_ }
4 "word2" {"Multi-match Exact " + $_ }
5 "w.*2" {"Pattern match Exact " + $_ }
6 default {"Multi-match Default " + $_ }
7}
Output:
1Multi-match Exact word1
2Multi-match Exact word2
3Pattern match Exact word2
4Multi-match Default word3
Comparison Operators
The following operators can be used in the condition expressions.
| Operator | Description | Example (true) |
|---|---|---|
| -eq | Equal | 1 -eq 1 |
| -ne | Not equal | 1 -ne 2 |
| -gt -ge | Greater than, greater than or equal to | 2 -gt 1 1 -ge 1 |
| -lt -le | Less than, less than or equal to | 1 -lt 2 1 -le 1 |
| -like | Like - for text using wildcards | “abc.efg” -like “?bc.*” |
| -notlike | Not Like | “abc.efg” -notlike “b*” |
| -contains | Contains | 1,2,3 -contains 1 |
| -notcontains | Not Contains | 1,2,3 -notcontains 4 |
Note:
- Prepend “i” for a case-insensitive operation. (e.g. -ieq)
- Prepend “c” for a case-sensitive operation. (e.g. -ceq)
Logical Operators
The following operators can be used for logical operations.
| Operator | Description | Example (true) |
|---|---|---|
| -and | Logical AND | (1 -eq 1) -and (1 -ne 2) |
| -or | Logical OR | (1 -eq 1) -or ($FALSE) |
| -not or ! | Logical NOT | -not ($FALSE) |
Binary Operators
The following operators can be used for binary operations.
| Operator | Description |
|---|---|
| -band | Binary AND |
| -bor | Binary OR |
| -bnot | Binary NOT |
String Operators
The following operators can be used on strings.
| Operator | Description |
|---|---|
| + | Concatenate two strings |
| * | Repeat a string some number of times |
| -f | Format a string (.NET format specifiers) |
| -replace | Replace operator "abcd” -replace “bc”, “TEST" aTESTd |
| -match | Regular expression match |
| -like | Wildcard matching |
Type Operators
The following operators can be used on types.
| Operator | Description | Example (true) |
|---|---|---|
| -is | Type evaluator | $a -is [string] |
| -as | Type converter | 100 -as [string] |
Command Expansion Operators
The following operators can be used for command expansion.
| Operator | Description |
|---|---|
| $( ) | Returns null |
| $(1,2,3) | Returns an array containing 1,2,3. |
| $(Get-Alias a*) | Returns evaluation of the expression |
| @(Get-Alias;Get-Process) | Executes the two commands and returns the results in an array |
Other Operators
| Operator | Description | Example (true) |
|---|---|---|
| , | Array constructor | |
| .. | Range operator | |
| & | Invoke a script block or the name of a command or function | $a = “Get-Process" &$a $a = { Get-Process | Select -First 2 } &$a |
Boolean Expressions
The following expressions will result in a boolean value of $TRUE or $FALSE.
| TRUE | FALSE |
|---|---|
| Any string of length > 0 except the word “false” | Empty string or the string “false” |
| Any number !=0 | Any number = 0 |
| Array of length > 1 | Array of length 0 |
| Array of length 1 whose element is TRUE | Array of length 1 whose element is FALSE |
| A reference to any object | Null |
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