The PowerShell escape character is the grave-accent(`)
The escape character can be used in three ways:
1) When used at the end of a line, it is a continuation character - so the command will continue on the next line.
2) To indicate that the next character following should be passed without substitution. For example $myVariable will normally be expanded to display the variables contents but `$myVariable will just be passed as $myVariable
3) When used inside double quotation marks, the escape character indicates that the following character should be interpreted as a 'special' character.
Special characters are used to format/position string output.
`0 Null `a Alert bell/beep `b Backspace `f Form feed (use with printer output) `n New line `r Carriage return `r`n Carriage return + New line `t Horizontal tab `v Vertical tab (use with printer output)
Using the Escape character to avoid special meaning.
`` To avoid using a Grave-accent as the escape character `# To avoid using # to create a comment `' To avoid using ' to delimit a string `" To avoid using " to delimit a string
When setting a string variable the # character does not need to be escaped, but at the command line # will act as a comment unless escaped:
PS C:\> echo 1 # 1
PS C:\> echo 1 `# 1
The escaped quotes allow quotation marks to be displayed on screen rather than being interpreted as the start or end of a string. The same effect can also be achieved by doubling-up the quote marks: "" or ''
For powershell.exe, the horizontal tab stops are every 8th character.
PS C:\> Write-Host "First Line `nSecond line" First Line Second Line PS C:\> "12`t90`n1234567890" 12 90 1234567890 PS C:\> Write-Host "Header1`tHeader2 `n123.45`t600" Header1 Header2 123.45 600 PS C:\> "`a `a"
<Two audible beeps are produced.>
Either single or double quotes may be used to specify a literal string.
Single-Quoted Strings (')
When you enclose a string in single quotation marks, any variable names in the string such as '$myVar' will appear exacly as typed when the command is processed. Expressions in single-quoted strings are not evaluated, not even escape characters or any of the Special characters listed above. If the string contains any embedded single quotes, they must be doubled (replace ' with '')
$msg = 'Every "lecture" should cost $5000'
Double-Quoted Strings (")
When you enclose a string in double quotation marks, any variable names in the string such as "$myVar" will be replaced with the variable's value when the command is processed. You can prevent this substitution by prefixing the $ with an escape character. Any embedded double quotes can be escaped `" or doubled (replace " with "")
$msg = "Every ""lecture"" should cost `$5000"
$msg = "Every 'lecture' should cost `$5000"
$var = 45
"The value of " + '$var' + "is '$var'"
"The value of `$var is '$var'"
$query = "SELECT * FROM Customers WHERE Name LIKE '%JONES%'"
In PowerShell 3.0 the special marker --% is a signal to PowerShell to stop interpreting any remaining characters on the line. This can be used to call a non-PowerShell utility and pass along some quoted parameters exactly as is.
for example instead of escaping every character that PowerShell may interpret:
PS C:\> FIND.EXE '"Search Text"' "C:\Program Files `(x86`)\Demo\text.txt"
we can instead use:
PS C:\> FIND.EXE --% "Search Text" "C:\Program Files (x86)\Demo\text.txt"
Any PowerShell variables after the --% won’t be expanded but you can work around this by building up the command string using more than one variable:
$command = 'FIND.EXE --%'
$params = "C:\Program Files (x86)\Demo\text.txt"
& $command "Search Text" $params;
If the command type is Application, the parameter --% is not passed to the command. The arguments after --% have any environment variables (strings surrounded by %) automatically expanded. For example:
PS C:\> FINDSTR.EXE --% "%ProgramFiles%"
In the above %ProgramFiles% is replaced with the value $env:ProgramFiles
Concatenate strings with +
In many cases, when combining simple strings, the + operator is not needed:
PS C:\> $first = "abcde"
PS C:\> $second = "FGHIJ"
PS C:\> "$first $second"
but when combining more complex objects, the + operator becomes very useful:
For example if we retrieve an environment variable
$drive = gci env:SystemDrive
This returns a DictionaryEntry object with .name and .value properties.
# Adding this to a string will give the wrong result
PS C:\> "aaa $drive bbb"
aaa System.Collections.DictionaryEntry bbb
# Concatenating it with a string is closer, but still wrong:
PS C:\> "aaa " + $drive + " bbb"
aaa System.Collections.DictionaryEntry bbb
# Specify the .value property and concatenate that with + to get the desired result:
PS C:\> "aaa " + $drive.value + " bbb"
aaa C: bbb
# Alternatively use the $( ) SubExpression operator:
PS C:\> "aaa $($drive.value) bbb"
aaa C: bbb
(an easier method would be using $drive = $env:SystemDrive which will return a system.string in the first place.)
In many programming languages including C# (.Net) and most UNIX shells the escape character is \
PowerShell is a Windows shell, and Windows already uses the backslash as a path separator C:\Windows\….
In Windows CMD the escape character is ^ although this was not a great choice as ^ is a valid character in NTFS filenames.
The PowerShell designers could have adopted the forward slash as a path separator C:/Windows/… , and then allocated the backslash as the escape character but this would have caused huge confusion and so instead they left paths unchanged and allocated ` as the escape character.
The backtick ` is a valid character in NTFS filenames, so should you encounter one in a filename, it will need to be escaped.
In some PowerShell expressions (matching operations) a backslash character will be interpreted as the start of a Regular Expression, (e.g. \w = match word)
To escape this and treat the backslash as an ordinary character, double it (replace \ with \\ )
A here string is a
single-quoted or double-quoted string which can span multiple lines.
Expressions in single-quoted strings are not evaluated.
All the lines in a here-string are interpreted as strings, even though they are not enclosed in quotation marks.
$myHereString = @'
some text with "quotes" and variable names $printthis
some more text
$anotherHereString = @"
The value of `$var is $var
some more text
Inside a here-string, double and single quotes are not special but quoted literally, all line breaks are preserved.
The @ character is also used to create arrays, create hash tables and as a splat operator.
Delimiters separate one parameter from the next - they split the command line up into words.
The standard delimiter for PowerShell is the space character, in addition the split operator and import-csv both accept options for splitting strings with a choice of delimiter.
“Be not angry that you cannot make others as you wish them to be, since you cannot make yourself as you wish to be” - Thomas A Kempis
Bug report - Executing commands which require quotes and variables is practically impossible.
Escaping Distinguished Names - Richard L. Mueller
Using PowerShell to run old command line tools - Jose Barreto
Invoke-Expression - Run a PowerShell expression
Join-Path - Combine a path and child-path
Pipelines - Pass objects down the pipeline
Variables - PowerShell Variables (int, String)