How can I remove lines that do not match a pattern? - powershell

I want to remove lines from a variable that does not match a pattern and save output to another variable using PowerShell.
Consider variable $value with contents:
"1609.68956.43566"
"1699809.89.412"
"1699.68.436"
"1699809.956.6"
"Heloo\this is"
"HI"
The requirement is to remove all lines except matching pattern "16*"
Expected output
"1609.68956.43566"
"1699809.89.412"
"1699.68.436"
"1699809.956.6"
Tried searching around but could not locate the commands

Now I did this on Powershell v5 so if this doesn't work on Powershell v2... oops. Anyway you should able use RegEx to match a pattern.
$newvariable = $value -match "^16"
This will assign the matching values from $value to $newvariable; "^16" tells it to match anything starting with 16, it won't match anything that starts with anything else (so e.g. 2016 won't match).

Related

match string pattern by certain characters but exclude combinations of those characters

I have the following sample string:
'-Dparam="x" -f hello-world.txt bye1.txt foo_bar.txt -Dparam2="y"'
I am trying to use RegEx (PowerShell, .NET flavor) to extract the filenames hello-world.txt, bye1.txt, and foo_bar.txt.
The real use case could have any number of -D parameters, and the -f <filenames> argument could appear in any position between these other parameters. I can't easily use something like split to extract it as the delimiter positioning could change, so I thought RegEx might be a good proposition here.
My attempt is something like this in PowerShell (can be opened on any Windows system and copy pasted into it):
'-Dparam="x" -f hello-world.txt bye1.txt foo_bar.txt -Dparam2="y"' -replace '^.* -f ([a-zA-Z0-9_.\s-]+).*$','$1'
Desired output:
hello-world.txt bye1.txt foo_bar.txt
My problem is that I either only take hello-world.txt, or I get hello-world.txt all the way to the end of the string or next = symbol (as in the example above).
I am having trouble expressing that \s is allowed, since I need to capture multiple space-delimited filenames, but that the combination of \s-[a-zA-Z] is not allowed, as that indicates the start of the next argument.

My Perl variable to variable substitutions do not work

I have a substitution to make in a Perl script, which I do not seem to get working. I have a string in a text file which has the form:
T+30H
The string T+30H has to be written in many files and has to change from file to file. It is two digits and sometimes three digits. First I define the variable:
my $wrffcr=qr{T+\d+H};
After reading the file containing the string, I have the following substitution command (starting with the file capture)
#scrptlines=<$NCLSCRPT>;
foreach $scrptlines (#scrptlines) {
$scrptlines =~ s/$wrffcr/T+$fcrange2[$jj]H/g;
}
$fcrange2[$jj] is defined and I confirm its value by printing its value just before the above 4 lines of code.
print "$fcrange2[$jj]\n";
When I run my script, nothing changes for this particular substitution. I suspect it is to do with the way I define the string to be substituted.
I will appreciate any assistance.
Zilore Mumba
Watch out for the first + in my $wrffcr=qr{T+\d+H};. It'll make it match 1 or more Ts, not T followed by a +. You probably want
my $wrffcr=qr{T\+\d+H};

String variable position being overwritten in write-host

If I run the below code, $SRN can be written as output or added to another variable, but trying to include either another variable or regular text causes it to be overwritten from the beginning of the line. I'm assuming it's something to do with how I'm assigning $autocode and $SRN initially but can't tell what it's trying to do.
# Load the property set to allow us to get to the email body.
$item.load($psPropertySet) # Load the data.
$bod = ($item.Body.Text -creplace '(?m)^\s*\r?\n','') -split "\n" # Get the body text, remove blank lines, split on line breaks to create an array (otherwise it is a single string).
$autocode = $bod[4].split('-')[2] # Get line 4 (should be Title), split on dash, look for 3rd element, this should contain our automation code.
$SRN = $bod[1] -replace 'ID: ','' # Get line 2 (should be ID), find and replace the preceding text.
# Skip processing if autocode does not match our list of handled ones.
if ($autocode -cin $autocodes)
{
write-host "$SRN $autocode"
write-host "$autocode $SRN"
write-host "$SRN test"
$var = "$SRN $autocode"
$var
}
The code results in this, you can see if $SRN isn't at the start of the line it is fine. Unsure where the extra spaces come from either:
KRNE8385
KRNE SR1788385
test8385
KRNE8385
I would expect to see this:
SR1788385 KRNE
KRNE SR1788385
SR1788385 test
SR1788385 KRNE
LotPings pointed me down the right path, both variables still had either "0D" or "\r" in them. My regex replace was only getting rid of them on blank lines, and I split the array on "\n" only. Changing line 3 in the original code to the below appears to have resolved the issue. First time seeing Format-Hex, but it appears to be excellent for troubleshooting such issues.
$bod = ($item.Body.Text -creplace '(?m)^\s*\r?\n','') -split "\r\n"

Partial String Replacement using PowerShell

Problem
I am working on a script that has a user provide a specific IP address and I want to mask this IP in some fashion so that it isn't stored in the logs. My problem is, that I can easily do this when I know what the first three values of the IP typically are; however, I want to avoid storing/hard coding those values into the code to if at all possible. I also want to be able to replace the values even if the first three are unknown to me.
Examples:
10.11.12.50 would display as XX.XX.XX.50
10.12.11.23 would also display as XX.XX.XX.23
I have looked up partial string replacements, but none of the questions or problems that I found came close to doing this. I have tried doing things like:
# This ended up replacing all of the numbers
$tempString = $str -replace '[0-9]', 'X'
I know that I am partway there, but I aiming to only replace only the first 3 sets of digits so, basically every digit that is before a '.', but I haven't been able to achieve this.
Question
Is what I'm trying to do possible to achieve with PowerShell? Is there a best practice way of achieving this?
Here's an example of how you can accomplish this:
Get-Content 'File.txt' |
ForEach-Object { $_ = $_ -replace '\d{1,3}\.\d{1,3}\.\d{1,3}','xx.xx.xx' }
This example matches a digit 1-3 times, a literal period, and continues that pattern so it'll capture anything from 0-999.0-999.0-999 and replace with xx.xx.xx
TheIncorrigible1's helpful answer is an exact way of solving the problem (replacement only happens if 3 consecutive .-separated groups of 1-3 digits are matched.)
A looser, but shorter solution that replaces everything but the last .-prefixed digit group:
PS> '10.11.12.50' -replace '.+(?=\.\d+$)', 'XX.XX.XX'
XX.XX.XX.50
(?=\.\d+$) is a (positive) lookahead assertion ((?=...)) that matches the enclosed subexpression (a literal . followed by 1 or more digits (\d) at the end of the string ($)), but doesn't capture it as part of the overall match.
The net effect is that only what .+ captured - everything before the lookahead assertion's match - is replaced with 'XX.XX.XX'.
Applied to the above example input string, 10.11.12.50:
(?=\.\d+$) matches the .-prefixed digit group at the end, .50.
.+ matches everything before .50, which is 10.11.12.
Since the (?=...) part isn't captured, it is therefore not included in what is replaced, so it is only substring 10.11.12 that is replaced, namely with XX.XX.XX, yielding XX.XX.XX.50 as a result.

powershell - replace line in .txt file

I am using PowerShell and I need replace a line in a .txt file.
The .txt file always has different number at the end of the line.
For example:
...............................txt (first)....................................
appversion= 10.10.1
............................txt (a second time)................................
appversion= 10.10.2
...............................txt (third)...................................
appversion= 10.10.5
I need to replace appversion + number behind it (the number is always different). I have set the required value in variable.
How do I do this?
Part of this issue you are getting, which I see from your comments, is that you are trying to replace text in a file and saved it back to the same file while you are still reading it.
I will try to show a similar solution while addressing this. Again we are going to use -replaces functionality as an array operator.
$NewVersion = "Awesome"
$filecontent = Get-Content C:\temp\file.txt
$filecontent -replace '(^appversion=.*\.).*',"`$1$NewVersion" | Set-Content C:\temp\file.txt
This regex will match lines starting with "appversion=" and everything up until the last period. Since we are storing the text in memory we can write it back to the same file. Change $NewVersion to a number ... unless that is your versioning structure.
Not sure about what numbers you are keeping
About which part of the numbers, if any, you are trying to preserve. If you intend to change the whole number then you can just .*\. to a space. That way you ignore everything after the equal sign.
Yes, you can with regex.
Let call $myString and $verNumber the variables with text and version number
$myString = "appversion= 10.10.1";
$verNumber = 7;
You can use -replace operator to get the version part and replace only last subversion number this way
$mystring -replace 'appversion= (\d+).(\d+).(\d+)', "appversion= `$1.`$2.$verNumber";