powershell - Renaming files with string extracted from filename -

i have following code in powershell script:

#call bluezone file transfer #start-process "\\fhnsrv01\home\aborgetti\documentation\projects\automation\openbz.bat" #variable declarations $a = get-date $b = $a.tostring('mmddyy') $source = "\\fhnsrv01\home\aborgetti\documentation\stage\" $dest = "\\fhnsrv01\home\aborgetti\documentation\stage\orig" #find files have ediprod extension , proceed process them #first copy original file orig folder before manipulation takes place copy-item $source\*.ediprod $dest # must rename items in table switch(gci \\fhnsrv01\home\aborgetti\documentation\stage\*.ediprod){     {(gc $_|select -first 1).substring(176) -match "^834"}{$_ | rename-item -newname {"834dailyin$b"};continue}     {(gc $_|select -first 1).substring(176) -match "^820"}{$_ | rename-item -newname {"820dailyin$b"};continue} } 

the part i'm concerned here:

switch(gci \\fhnsrv01\home\aborgetti\documentation\stage\*.ediprod){     {(gc $_|select -first 1).substring(176) -match "^834"}{$_ | rename-item -newname {"834dailyin$b"};continue}     {(gc $_|select -first 1).substring(176) -match "^820"}{$_ | rename-item -newname {"820dailyin$b"};continue} } 

i appending variable $b @ end of filename. holds date. however, real date i'm interested in in filename itself, , looks this:

aidoccai.d051414.t025848.mo.ediprod

i need have powershell extract d051414 date 051414 , append end of file.

otherwise repeatedly error: cannot rename-item because item exists.

can this? keep original structure of switch statement works well. having date on there however, not. file comes once day, every file have different date , work, need on how there.

update

switch(gci \\fhnsrv01\home\aborgetti\documentation\stage\*.ediprod){     {(gc $_|select -first 1).substring(176) -match "^834"}{$_ | {$_ | ?{$_.name -match "^.+?\.d(\d{6}).*"} | rename-item -newname {"834dailyin$($matches[1])"}}     {(gc $_|select -first 1).substring(176) -match "^820"}{$_ | {$_ | ?{$_.name -match "^.+?\.d(\d{6}).*"} | rename-item -newname {"820dailyin$($matches[1])"}} } 

update 834 rename line replace switch's scripteblock read:

{$_ | ?{$_.name -match "^.+?\.d(\d{6}).*"} | rename-item -newname {"834dailyin$($matches[1]).txt"};continue}