hi
i am a newbie in linux ,i am writing a bash script to identify the files which are exactly 7 days ( a week old)
i tried this command
find /var/backup -mtime +7 -exec ls -d {} \;
but this gives me even the files which are older than 7 days

[root@proxy access]# find . -mtime +7 -exec ls -d {} \;
./access.log.1.gz
./access.log.2.gz
./access.log.2.gz19Apr10
./access.log.3.gz
./access.log.3.gz19Apr10
./access.log.4.gz

[root@proxy access]# ll
-rwxrwxrwx 1 root root 48869073 Mar 7 04:02 access.log.4.gz
-rwxrwxrwx 1 root root 53259282 Mar 14 04:03 access.log.3.gz
-rwxrwxrwx 1 root root 58549296 Mar 21 04:03 access.log.2.gz
-rwxrwxrwx 1 root root 72788051 Mar 28 04:03 access.log.1.gz
-rwxrwxrwx 1 root root 68077106 Apr 4 04:03 access.log.3.gz19Apr10
-rwxrwxrwx 1 root root 70632288 Apr 11 04:03 access.log.2.gz19Apr10
-rwxrwxrwx 1 root root 68914245 Apr 18 04:03 access.log.1.gz19Apr10

i want only the file which is 7 days old

You can try something like:
where -daystart measures time from today at 00:00. You can find more details on the GNU findutils manual, here.

info find shows this:

-- Option: -daystart
Measure times from the beginning of today rather than from 24 hours
ago. So, to list the regular files in your home directory that
were modified yesterday, do

find ~ -daystart -type f -mtime 1

Bear in mind that mtime is the modification time, there are also tests for the atime and ctime which you might like to examine.

+ and - before the time gives you a range, so +1 giver everything 1 day and older.

If you actually want files that are exactly 7 days old from the current time, don't use daystart.

True. To clarify, using -daystart and -mtime 7 from today (2009-04-19) you will find files last modified between 2009-04-12 00:01 and 2009-04-13 00:00.

Without -daystart you have to consider files modified 7*24 hours ago from the current time, always in the range of 24 hours. Suppose now is 11:55, using only -mtime 7 you will find files modified between 2009-04-11 11:56 and 2009-04-12 11:55.