unix script to takes the old data from a TXT file and compress them into new file

Shell Programming and Scripting
1

Hi,
I am looking for the unix script which can takes the 2 month old data from a TXT file (there is one txt file in whiche messages are appended on daily basis) and compress them into new file.Please halp me out.

2

but, in theory...
just split the file in two based on some critera

criteria will be effected by such things as:
(a) should it be run just monthly, or daily
(b) is the log file always open
--> this can cause some complications in the removal process
(c) is the posting date part of the record structure

3

Please find the answeres :
(a) monthly basis
(b) is the log file always open :NO
(c) is the posting date part of the record structure :yes

Thanks