Shell Programming and Scripting

Hi,
I have a Unix mail file that I need to truncate, based on the date of the messages. For those not familiar with the format, it is a single file for each user, with the first line of the mail message looking like the following:

From user@sitename.com Thu Apr 21 05:40:33 2011

Each succeeding message is separated by a blank line. I need to only keep 2 days worth of messages. What I would like to do is find the line for the first message from 2 days ago, and then delete all the lines in the mail file above this entry. Any ideas?

A picture is worth a thousand of words.

By not displaying a sample of the input and output data, you will not allow people to understand your requirement properly, thus they will not answer it.

Nevertheless, I'll give it a shot:

Code:

#!/bin/bash

mail=/var/spool/mail/$USER

#get the first date that's within last two days:
D=$( egrep "^From " $mail |  #filter the lines starting with 'From '
     sed 's/^From [^ ][^ ]*//'  |  #get only the date
     while read D ; do   #loop through dates
         [[ $((`date +%s`-`date -d "$D" +%s`)) -lt $((2*24*3600)) ]]  && echo $D && break  #compare and exit loop as soon as you find one that's within 2 days
     done )

#print only from this date on:
 sed -n "/^From .* $D/,$ p" $mail

Wow, Mirni. That's exactly what I needed. Thanks.