I want to use the $_ in a Pattern in Powershell. I have the following script but it doesn't work
Get-Content ..\myfile.txt | ForEach-Object {
$counter=(gc *.log | Select-String -Pattern '$_\/Directory\/Cars\/Sign.jpg')
}
If I run the script, in lines of the myfile.txt which I know there is some ocurrences according to the Pattern it finds 0, so how I must write the $_ in the pattern?.
Thanks so much
The reason PowerShell isn't expanding $_ is because you're using a verbatim string literal (a string literal defined using ' single-quotes).
For an expandable string literal, you need to use " double-quotes - PowerShell will then attempt to expand variable expressions inside the string:
Get-Content ..\myfile.txt | ForEach-Objet {
$counter=(gc *.log | Select-String -Pattern "${_}/Directory/Cars/Sign\.jpg")
}
Note: ${_} is the same variable as $_.
The explicit {} qualifiers prevents PowerShell from interpreting something that isn't actually part of the variable name as such. Let's say your pattern looked like "$_Sign\.jpg", PowerShell would attempt to resolve the token $_Sign instead of just $_, whereas "${_}Sign\.jpg" makes it obvious to PowerShell's parser where the variable expression ends.
Depending on what myfile.txt contains, you might want to escape the input string:
Get-Content ..\myfile.txt | ForEach-Object {
$counter=(gc *.log | Select-String -Pattern "$([regex]::Escape($_))/Directory/Cars/Sign\.jpg")
}
For further reading on these topics, peruse the about_Quoting_Rules and about_Regular_Expressions help topics
Related
I am trying to replace every instance of a string within a directory. However my code is not replacing anything.
What I have so far:
Test Folder contains multiple files and folders containing content that I need to change.
The folders contain .txt documents, the .txt documents contain strings like this: Content reference="../../../PartOfPath/EN/EndofPath/Caution.txt" that i need to change into this: Content reference="../../../PartOfPath/FR/EndofPath/Caution.txt"
Before this question comes up, yes it has to be done this way, as there are other similar strings that I don't want to edit. So I cannot just replace all instances of EN with FR.
$DirectoryPath = "C:\TestFolder"
$Parts =#(
#{PartOne="/PartOfPath";PartTwo="EndofPath/Caution.txt"},
#{PartOne="/OtherPartOfPath";PartTwo="EndofPath/Note.txt"},
#{PartOne="/ThirdPartOfPath";PartTwo="OtherEndofPath/Warning.txt"}) | % { New-Object object | Add-Member -NotePropertyMembers $_ -PassThru }
Get-ChildItem $DirectoryPath | ForEach {
foreach($n in $Parts){
[string]$PartOne = $n.PartOne
[string]$PartTwo = $n.PartTwo
$ReplaceThis = "$PartOne/EN/$PartTwo"
$WithThis = "$PartOne/FR/$PartTwo"
(Get-Content $_) | ForEach {$_ -Replace $ReplaceThis, $WithThis} | Set-Content $_
}
}
The code will run and overwrite files, however no edits will have been made.
While troubleshooting I came across this potential cause:
This test worked:
$FilePath = "C:\TestFolder\Test.txt"
$ReplaceThis ="/PartOfPath/EN/Notes/Note.txt"
$WithThis = "/PartOfPath/FR/Notes/Note.txt"
(Get-Content -Path $FilePath) -replace $ReplaceThis, $WithThis | Set-Content $FilePath
But this test did not
$FilePath = "C:\TestFolder\Test.txt"
foreach($n in $Parts){
[string]$PartOne = $n.PartOne
[string]$PartTwo = $n.PartTwo
[string]$ReplaceThis = "$PartOne/EN/$PartTwo"
[string]$WithThis = "$PartOne/FR/$PartTwo"
(Get-Content -Path $FilePath) -replace $ReplaceThis, $WithThis | Set-Content $FilePath
}
If you can help me understand what is wrong here I would greatly appreciate it.
Thanks to #TessellatingHeckler 's comments I revised my code and found this solution:
$DirectoryPath = "C:\TestFolder"
$Parts =#(
#{PartOne="/PartOfPath";PartTwo="EndofPath/Caution.txt"},
#{PartOne="/OtherPartOfPath";PartTwo="EndofPath/Note.txt"},
#{PartOne="/ThirdPartOfPath";PartTwo="OtherEndofPath/Warning.txt"}) | % { New-Object object | Add-Member -NotePropertyMembers $_ -PassThru }
Get-ChildItem $LanguageFolderPath -Filter "*.txt" -Recurse | ForEach {
foreach($n in $Parts){
[string]$PartOne = $n.PartOne
[string]$PartTwo = $n.PartTwo
$ReplaceThis = "$PartOne/EN/$PartTwo"
$WithThis = "$PartOne/FR/$PartTwo"
(Get-Content $_) | ForEach {$_.Replace($ReplaceThis, $WithThis)} | Set-Content $_
}
}
There were two problems:
Replace was not working as I intended, so I had to use .replace instead
The original Get-ChildItem was not returning any values and had to be replaced with the above version.
PowerShell's -replace operator is regex-based and case-insensitive by default:
To perform literal replacements, \-escape metacharacters in the pattern or call [regex]::Escape().
By contrast, the [string] type's .Replace() method performs literal replacement and is case-sensitive, invariably in Windows PowerShell, by default in PowerShell (Core) 7+ (see this answer for more information).
Therefore:
As TessellatingHeckler points out, given that your search strings seem to contain no regex metacharacters (such as . or \) that would require escaping, there is no obvious reason why your original approach didn't work.
Given that you're looking for literal substring replacements, the [string] type's .Replace() is generally the simpler and faster option if case-SENSITIVITY is desired / acceptable (invariably so in Windows PowerShell; as noted, in PowerShell (Core) 7+, you have the option of making .Replace() case-insensitive too).
However, since you need to perform multiple replacements, a more concise, single-pass -replace solution is possible (though whether it actually performs better would have to be tested; if you need case-sensitivity, use -creplace in lieu of -replace):
$oldLang = 'EN'
$newLang = 'FR'
$regex = #(
"(?<prefix>/PartOfPath/)$oldLang(?<suffix>/EndofPath/Caution.txt)",
"(?<prefix>/OtherPartOfPath/)$oldLang(?<suffix>/EndofPath/Note.txt)",
"(?<prefix>/ThirdPartOfPath/)$oldLang(?<suffix>/OtherEndofPath/Warning.txt)"
) -join '|'
Get-ChildItem C:\TestFolder\Test.txt -Filter *.txt -Recurse | ForEach-Object {
($_ |Get-Content -Raw) -replace $regex, "`${prefix}$newLang`${suffix}" |
Set-Content -LiteralPath $_.FullName
}
See this regex101.com page for an explanation of the regex and the ability to experiment with it.
The expression used as the replacement operand, "`${prefix}$newLang`${suffix}", mixes PowerShell's up-front string interpolation ($newLang, which could also be written as ${newLang}) with placeholders referring to the named capture groups (e.g. (?<prefix>...)) in the regex, which only coincidentally use the same notation as PowerShell variables (though enclosing the name in {...} is required; also, here the $ chars. must be `-escaped to prevent PowerShell's string interpolation from interpreting them); see this answer for background information.
Note the use of -Raw with Get-Content, which reads a text file as a whole into memory, as a single, multi-line string. Given that you don't need line-by-line processing in this case, this greatly speeds up the processing of a given file.
As a general tip: you may need to use the -Encoding parameter with Set-Content to ensure the desired character encoding, given that PowerShell never preserves a file's original coding when reading it. By default, you'll get ANSI-encoded files in Windows PowerShell, and BOM-less UTF-8 files in PowerShell (Core) 7+.
I am trying to replace the text ($) with quotation marks in a text file by using PowerShell
Here is the code I am trying, But not giving expected results:
$FilePath = "C:\PT\Test\"
Get-ChildItem $FilePath -Filter *.TXT | ForEach-Object {
(Get-Content $_.FullName) | Foreach-Object {
$_ -replace ',"$"', ',"$",'
} | Set-Content $_.FullName
}
As pointed out by Abraham in his comment, the $ is a reserved character in regex known as Anchor, if you want to match a literal $ using -replace you would need to escape it: \$:
Get-ChildItem $FilePath -Filter *.TXT | ForEach-Object {
(Get-Content $_.FullName -Raw) -replace ',"\$"',',"$",' |
Set-Content $_.FullName
}
The other alternative is to use the .Replace(..) string method which will match literal characters.
Get-ChildItem $FilePath -Filter *.TXT | ForEach-Object {
(Get-Content $_.FullName -Raw).Replace(',"$"',',"$",') |
Set-Content $_.FullName
}
By looking at your code seems like you want to replace ,"$" with ,"$",, if this was not the case let me know.
The -replace operator:
uses a regex as the search-pattern operand, and therefore requires a verbatim $ to be escaped as \$ in order to be interpreted as such (an unescaped $ is a regex metacharacter representing the end of the input string)
also uses $ as a metacharacter in the substitution operand, namely to refer to the text that the regex captured ($&) or parts thereof (e.g. $1 to refer to what the first capture group ((...)) captured). In this case, escape it as $$.
Note: Situationally, even an unescaped $ may work, namely if, in combination with the subsequent characters, if any, it cannot be interpreted as a placeholder such as $& or $1. However, in the interest of robustness it is better to escape.
Therefore, use:
PS> ',"$"20' -replace ',"\$"', ',"$$",'
,"$",20
Taking a step back:
As Abraham Zinala suggests, for verbatim string replacements, the .Replace() string method is sufficient, whose use doesn't necessitate escaping, and which is faster to boot:
PS> ',"$"20'.Replace(',"$"', ',"$",')
,"$",20
Caveat: Unlike -replace, .Replace() is case-sensitive - invariably in Windows PowerShell and by default in PowerShell (Core) 7+.
See this answer for a detailed juxtaposition of -replace and .Replace(), including how to perform escaping for -replace programmatically.
To put it all together, along with an optimization that reads each file in full, with Get-Content -Raw, for much faster processing (to avoid appending a trailing newline, -NoNewLine is used with Set-Content):
$FilePath = "C:\PT\Test"
Get-ChildItem $FilePath -Filter *.TXT | ForEach-Object {
(Get-Content -Raw $_.FullName).Replace(',"$"', ',"$",') |
Set-Content -NoNewLine $_.FullName
}
I want to use the method given in the answer of this question:
PowerShell - Remove all lines of text file until a certain string is found
However I don't get my string from "Get-Content"; I get it from "Out-String". How can I convert my "Out-String" variable into a "Get-Content" format without needing to "Set-Content"/"Get-Content" a temporary file? Or how can I get the same end result without even converting?
It really hurts my brains that a "Get-Member" on the variable from either 'Out-String' or 'Get-Content' returns a TypeName of System.String but you cannot use them the same way...
Here is the simplified code I've been trying to understand - let's use that:
# Let's work with the text from 'Get-Help' output:
$myString = (Get-Help | out-string)
# I only want the text from the "SEE ALSO" section:
$cut = $myString.Where({ $_ -like ("*SEE ALSO*") },'SkipUntil')
$cut # This shows the whole thing!!! :-(
$cut | gm | findstr TypeName # says 'TypeName: System.String'
# Dirty conversion to "Get-Content" format:
Set-Content "tmp.file" -value $cut
$recut = (Get-Content "tmp.file").Where({ $_ -like ("*SEE ALSO*") },'SkipUntil')
$recut # Now this shows what I want, even though the below returns 'TypeName: System.String' as well !!!
(Get-Content "tmp.file") | gm | findstr TypeName
The problem is get-help (with no parameters) or out-string is outputting one multiline string (with windows line endings). I even tried out-string -stream. This is unusual for a powershell command. Get-content would split up the lines for you automatically.
(get-help).count
1
One way to resolve it is to split on the line endings. I'm also skipping blank lines at the end. (This split pattern works with unix/osx text too.)
((get-help) -split '\r?\n').Where({ $_ -like '*SEE ALSO*' },'SkipUntil') | where { $_ }
SEE ALSO:
about_Updatable_Help
Get-Help
Save-Help
Update-Help
Or:
((get-help) -split '\r?\n').Where({ $_ -match 'SEE ALSO' },'SkipUntil').Where{ $_ }
In this case, you do not even need Out-String, but I will stick to your example:
$myString = (Get-Help | Out-String)
$mystring -match "(?ms)^.*(SEE\sALSO.*)$" | Out-Null
$Matches[1]
The key in the regex is (?ms). m enables multi-line search and s enables wildcards to span over multiple lines (in other words: including line breaks). The result of the -match operator is piped to Out-Null to not see it in the terminal. You might want to evaluate it though. If $true, $Matches[1] will contain your desired string.
Trying to edit this line of a file ("VoIP.Enabled "1"). I wanna change the 1 to a zero. When I change it with
$dewprefs = Get-Content .\dewrito_prefs.cfg
$dewprefs | Select-String "VoIP.Enabled" | ForEach-Object {$_ -replace "1","0"} | Set-Content .\dewrito_prefs.cfg}`
However when I use this script, it removes 100 other lines, edits the right line, then deletes everything else, just leaving the line I wanted to edit.
Any help on this matter would be highly appreciated
Select-String acts as a filter: that is, the input it is given is only passed out if it matches a pattern.
Therefore, only the line of interest is written to the output file.
Do not use Select-String if all input lines - though possibly modified - should be passed through; use only ForEach-Object, and conditionally modify each input line:
$dewprefs = Get-Content .\dewrito_prefs.cfg
$dewprefs |
ForEach-Object { if ($_ -match 'VoIP\.Enabled') { $_ -replace '1', '0' } else { $_ } } |
Set-Content .\dewrito_prefs.cfg
$_ -match 'VoIP\.Enabled' now does what Select-String did in your original command: it matches only if the input line at hand contains literal VoIP.Enabled (note how the . is escaped as \. to ensure that is treated as a literal in the context of a regular expression).
Note how both branches of the if statement produce output:
$_ -replace '1', '0' outputs the result of replacing all instances of 1 in the input line with 0
$_ simply passes the input line through as-is.
Most likely you could replace the if statement with a single -replace expression, however, and, assuming that the file is small enough to be read as a whole (quite likely, in the case of a configuration file), you can use a variant of Stu's helpful simplification.
Taking full advantage of the fact that -replace supports regexes (regular expressions), the code can update lines based on a key name such as VoIP.Enabled only, without needing to know that key's current value.
$key = 'VoIP.Enabled'
$newValue = '1'
# Construct a regex that matches the entire target line.
$regex = '^\s*' + [regex]::Escape($key) + '\b.*$'
# Build the replacement line.
$modifiedLine = "$key $newValue"
(Get-Content .\dewrito_prefs.cfg) -replace $regex, $modifiedLine | Set-Content .\dewrito_prefs.cfg
Note that writing the output back to the input file only works because the input file was read into memory as a whole, up front, due to enclosing the Get-Content call in (...).
This will work too, with PowerShell v3+, and is a little more succinct:
(Get-Content .\dewrito_prefs.cfg).replace('"VoIP.Enabled "1"', '"VoIP.Enabled "0"') |
Set-Content .\dewrito_prefs.cfg
Your quotes are a little strange (3 double quotes in total?), I've mimicked what you've asked, however.
I am replacing multiple strings in a file. The following works, but is it the best way to do it? I'm not sure if doing multiple block expressions is a good way.
(Get-Content $tmpFile1) |
ForEach-Object {$_ -replace 'replaceMe1.*', 'replacedString1'} |
% {$_ -replace 'replaceMe2.*', 'replacedString2'} |
% {$_ -replace 'replaceMe3.*', 'replacedString3'} |
Out-File $tmpFile2
You don't really need to foreach through each replace operations. Those operators can be chained in a single command:
#(Get-Content $tmpFile1) -replace 'replaceMe1.*', 'replacedString1' -replace 'replaceMe2.*', 'replacedString2' -replace 'replaceMe3.*', 'replacedString3' |
Out-File $tmpFile2
I'm going to assume that your patterns and replacements don't really just have a digit on the end that is different, so you might want to execute different code based on which regex actually matched.
If so you can consider using a single regular expression but using a function instead of a replacement string. The only catch is you have to use the regex Replace method instead of the operator.
PS C:\temp> set-content -value #"
replaceMe1 something
replaceMe2 something else
replaceMe3 and another
"# -path t.txt
PS C:\temp> Get-Content t.txt |
ForEach-Object { ([regex]'replaceMe([1-3])(.*)').Replace($_,
{ Param($m)
$head = switch($m.Groups[1]) { 1 {"First"}; 2 {"Second"}; 3 {"Third"} }
$tail = $m.Groups[2]
"Head: $head, Tail: $tail"
})}
Head: First, Tail: something
Head: Second, Tail: something else
Head: Third, Tail: and another
This may be overly complex for what you need today, but it is worth remembering you have the option to use a function.
The -replace operator uses regular expressions, so you can merge your three script blocks into one like this:
Get-Content $tmpFile1 `
| ForEach-Object { $_ -replace 'replaceMe([1-3]).*', 'replacedString$1' } `
| Out-File $tmpFile2
That will search for the literal text 'replaceMe' followed by a '1', '2', or '3' and replace it with 'replacedString' followed by whichever digit was found (the '$1').
Also, note that -replace works like -match, not -like; that is, it works with regular expressions, not wildcards. When you use 'replaceMe1.*' it doesn't mean "the text 'replaceMe1.' followed by zero or more characters" but rather "the text 'replaceMe1' followed by zero or more occurrences ('*') of any character ('.')". The following demonstrates text that will be replaced even though it wouldn't match with wildcards:
PS> 'replaceMe1_some_extra_text_with_no_period' -replace 'replaceMe1.*', 'replacedString1'
replacedString1
The wildcard pattern 'replaceMe1.*' would be written in regular expressions as 'replaceMe1\..*', which you'll see produces the expected result (no replacement performed):
PS> 'replaceMe1_some_extra_text_with_no_period' -replace 'replaceMe1\..*', 'replacedString1'
replaceMe1_some_extra_text_with_no_period
You can read more about regular expressions in the .NET Framework here.