Why following ksh script not works in crontab?

This is a multi-part message in MIME format. --------------4D5164B43D5D4EE60DD563E6 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit The following ksh script works well in command line. But not work in crontab, why? ----------------------------------------------------------------------- #!/bin/ksh # Informix back up logical log and will create a file logical.log ontape -a << EOF^M y^M EOF # where ^M is return input in vi by type ctrl-V and Enter sleep 3 hour=`date +%H` if [[ $hour -ge 9 && $hour -lt 12 ]] then cp logical.log logical_tape1.log else cp logical.log logical_tape2.log fi cat /dev/null > logical.log ------------------------------------------------------------------- The above script runs perfectly if on command line. But when I schedual in the crontab, I always got 0 (zero) size of logical_tape1/2.log. It seems to me the script does the "cp" command before the "ontape -a" processing finish. I even put a "sleep" between them. Why is that? Do I have to run the script in background in crontab? like 0 10,13 * * * mybackup_script & Currently I don't put in background "&" BTW, My OS is HP-UX 10.20, database is Informix Dynamic Server 7.3. For those who has OS Solaris 2.5/6.x, do you have this problem? To all, do you have solution for me? Thank you very much in advance! -- RC Square Team. --------------4D5164B43D5D4EE60DD563E6 Content-Type: text/x-vcard; charset=us-ascii; name="vcard.vcf" Content-Transfer-Encoding: 7bit Content-Description: Card for Chui /Chen, Raymond/Ruiming Content-Disposition: attachment; filename="vcard.vcf" begin: vcard fn: Raymond/Ruiming Chui /Chen n: Chui /Chen;Raymond/Ruiming org: RC Square adr: ;;;;;;U.S.A. email;internet: rctwo@erols.com title: CS tel;work: 301-498-8959 tel;fax: 301-498-8959 tel;home: URL http://www.erols.com/rctwo/ note: Raymond Chui & Ruiming Chen Company x-mozilla-cpt: ;0 x-mozilla-html: TRUE version: 2.1 end: vcard --------------4D5164B43D5D4EE60DD563E6--