Count occurrence of strings in a log.file with PowerShell - string

Question

I need to get the occurrence of "failure" in a logfile.
The thing is I need to get the occurrence of "failure" for each session block.
What the log looks like:
---Session 1
check
check
failure
failure
check
----Session 2
check
failure
check
check
----Session 3
failure
failure
What I've got so far is this:
$rows = Get-Childitem -Path E:\shell\lot.log |
Select-String -Pattern failure
$i = 0
foreach ($row in $rows) {
$i++
}
echo $i
With that script I only get the total of the occurrences.

Answer 1

I would start a new counter whenever a line beginning with 3 or more consecutive hyphens occurs and collect the results in a hashtable.
$failcount = #{}
Get-Content 'E:\shell\lot.log' | ForEach-Object {
if ($_ -match '^-{3,}(.*)') {
$section = $matches[1].Trim()
$failcount[$section] = 0
} elseif ($_ -like '*failure*') {
$failcount[$section]++
}
}

Answer 2

I believe this will do it. Key part is to reset your counter after each session.
$rows = Get-Childitem -Path E:\shell\lot.log
$i = 0 # failure counter
$j = 1 # session counter
foreach($row in $rows){
if($row -like "*Session 1"){
# skip the first line. Edit: removed * as would skip session 10, 11 etc. assumes line ends with "session 1"
continue
}elseif($row -eq "failure){
# if the row is equal to failure, count it
$i++
}elseif($row -like "*Session*"){
# when you get to the end of a session, print the number of failures
Write-Host "Session $j had $i failures"
# ... and reset the failure counter
$i = 0
# increment the session counter
$j++
}
}

Answer 3

I'll add another option. Read the whole log file in with -Raw to get a multi-line string. Remove the ---- from the first line, and then split on 3 or more hyphens at the beginning of a line, this gets you each session as a multi-line string, then you could just output text or custom objects, or whatever you wanted with it. Split the multi-line string on new line characters, filter for 'failure', and do a count to get failures per session.
(GC E:\shell\lot.log -Raw) -replace '^-+' -split '(?<=[\r\n])---+'|%{
'{0} had {1} failure(s)' -f ($_.split("`n")[0].Trim()),($_ -split '[\r\n]+'|?{$_ -match 'failure'}).Count
}
That would (given the sample provided) output:
Session 1 had 2 failure(s)
Session 2 had 1 failure(s)
Session 3 had 2 failure(s)