Scripting may not be what you earn for a living, but it still deserves a minimal of rigour to finish its little work. You have object reference(s) defined no where, constant/variable not assigned value properly, command line incorrect (even without the appending routine of my part)...
[tt]
'given
sSourceFile = "C:\anil\CBDSTSM01.TXT"
sDestinationFile = "C:\anil\CBDSTSM01.log"
strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
& "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set wshShell = WScript.CreateObject ("WSCript.shell")
' Run application
WshShell.Run "[highlight]""[/highlight]C:\Program Files\Tivoli\TSM\baclient\dsmadmc.exe[highlight]""[/highlight] -TCPSERVERADDRESS=CBDSTSM1 -TCPPORT=1610 -outfile=[blue]" & sSourceFile[/blue],1,true
' Append todays date and time to C:\anil\CBDSTSM01.log ..
[blue]Set pFSO = CreateObject("Scripting.FileSystemObject")[/blue]
[red]ForAppending=8[/red]
Set filetxt = [red]pFSO[/red].OpenTextFile(sDestinationFile, ForAppending, True)
filetxt.WriteLine("=================================================================")
filetxt.WriteLine("=================================================================")
filetxt.WriteLine( Todays data and time )
filetxt.WriteLine("=================================================================")
filetxt.WriteLine("=================================================================")
filetxt.Close
WScript.Sleep(80000)
[red]'[/red]
Set pFSO = CreateObject("Scripting.FileSystemObject") 'moved up
set ots=pFS

pentextfile(sSourceFile,1,true,[red]-2[/red]) 'using system default format(?)
s=""
on error resume next
s=s & ots.readall
on error goto 0
ots.close
set ots=pFS

pentextfile(sDestinationFile,8,true,[red]-2[/red])
ots.write s
ots.close
set ots=nothing
pFSO.DeleteFile sSourceFile, True
set pFSO=nothing
[/tt]