Powershell: Filter the contents of a file by an array of strings

Question

Riddle me this:

I have a text file of data. I want to read it in, and only output lines that contain any string that is found in an array of search terms.

If I were looking for just one string, I would do something like this:

get-content afile | where { $_.Contains("TextI'mLookingFor") } | out-file FilteredContent.txt

Now, I just need for "TextI'mLookingFor" to be an array of strings, where if $_ contains any string in the array, it is passed down the pipe to out-file.

How would I do that (and BTW, I'm a c# programmer hacking this powershell script, so if there is a better way to do my match above than using .Contains(), clue me in!)

score 40 · Accepted Answer · answered Feb 11 '13 at 22:44

Try Select-String . It allows an array of patterns. Ex:

$p = @("this","is","a test")
Get-Content '.\New Text Document.txt' | Select-String -Pattern $p -SimpleMatch | Set-Content FilteredContent.txt

Notice that I use -SimpleMatch so that Select-String ignores special regex-characters. If you want regex in your patterns, just remove that.

For a single pattern I would probably use this, but you have to escape regex characters in the pattern:

Get-Content '.\New Text Document.txt' | ? { $_ -match "a test" }

Select-String is a great cmdlet for single patterns too, it's just a few characters longer to write ^^

score 5 · Answer 2 · answered Feb 11 '13 at 22:51

5

Any help?

$a_Search = @(
    "TextI'mLookingFor",
    "OtherTextI'mLookingFor",
    "MoreTextI'mLookingFor"
    )


[regex] $a_regex = ‘(‘ + (($a_Search |foreach {[regex]::escape($_)}) –join “|”) + ‘)’

(get-content afile) -match $a_regex

answered Feb 11 '13 at 22:51

mjolinor

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Select string is probably a better choice, especially for file data. – mjolinor Feb 11 '13 at 23:12
Just ran a quick test, and -match works better for large numbers of reps (about 15x faster than select-string). – mjolinor Feb 11 '13 at 23:26
Thanks for the regex variation +1. I gave the answer to the select-string response because of the simplicity. – JMarsch Feb 12 '13 at 14:17
Unless I was doing it inside a very busy loop I would, too. :) – mjolinor Feb 12 '13 at 14:20

score 3 · Answer 3 · answered Feb 12 '13 at 01:26

3

without regex and with spaces possible:

$array = @("foo", "bar", "hello world")
get-content afile | where { foreach($item in $array) { $_.contains($item) } } > FilteredContent.txt

answered Feb 12 '13 at 01:26

Nacht

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score 1 · Answer 4 · answered Feb 11 '13 at 23:09

1

$a = @("foo","bar","baz")
findstr ($a -join " ") afile > FilteredContent.txt

answered Feb 11 '13 at 23:09

Ansgar Wiechers

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Powershell: Filter the contents of a file by an array of strings

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