Using PowerShell to count unique error messages in a log file

Question

I have several logs files with hundreds of lines in the following format:

{"time": 0800, "service":"A service", "id": 5, "error":"bad"}  
{"time": 0900, "service":"B service", "id": 6, "error":"good"}

I'd like to be able run through each file and output a table with a count of each unique error message .. something like this:

Error "bad" came up 5 times

Error "good" came up 3 times

I'm not sure if converting the content to JSON makes sense in this situation, but I have done the following so far to at least identify unique strings:

Get-Childitem -path "\path" | Select-string -Pattern "good"

and that gives me all the "good" messages.

It would seem to me that using a loop with a counter to capture unique events could be used. What would be the best way to achieve all of this with PowerShell?

Just a headsup, you can pipe your Command to Measure-Object and it will return you the number of lines. — Paxz
– Paxz, Commented Aug 2, 2018 at 9:42

Mathias R. Jessen · Accepted Answer · 2018-08-02 09:48:15Z

4

Convert the json strings in the file into objects with ConvertFrom-Json and then group them by the error property using Group-Object:

Get-Childitem -path "\path" |ConvertFrom-Json |Group-Object error -NoElement

answered Aug 2, 2018 at 9:48

Mathias R. Jessen

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2 Comments

Mathias R. Jessen Over a year ago

@Avshalom Argh, sorry dude, story of my life :-P

spex5 Over a year ago

great, that worked. One of the files is formatted in a way where the convertfrom-json cmdlet doesn't like it. There is only one line and it is like this, { "error" : "bad"}, but it is spread out on 3 lines. The error thrown is "Invalid object passed in ':' or '}". How can I skip files where the json is not recognized.. or how can I change it so it is recognized? Second follow up question. How can I access the properties of the object? For example, I want to display the "service" and "time" properties. I only get count, group, and name.

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