I hv a crontab job (script) that can be run normally , now I try to run it on the shell but can't be run , can advise what is difference between run a script on crontab and run it manually ? is it the difference of system enviornment ?thx

I tried to fix it by below method ,

I write a script /tmp/script1


#vi /tmp/script1
rlogn localhost -l cron_usr

#vi ~cron_usr/.profile
my_script

when I want is to make the crontab job will login the system and login as cron_usr .
If I run this script manually , it is OK , but if I run it by crontab job , it is not work , so I think run manully and by crontab is different , can advise how can I make it work ?

thx