[R] random number generator in batch jobs

[Jiqiu Cheng]

Dear sir,
   I want to submit R batch jobs (e.g. 5) under the linux cluster by  
the script file "do_mul".
The script file "do_mul"
"
#!/bin/bash
export var
for var in $(seq 1 5)
do
   qsub -v var do_test
done
exit 0
"
Through "do_mul", 5 "do_test" script files are submitted to the cluster.
The script file "do_test":
"
#!/bin/bash -l
#PBS -l ncpus=1
#PBS -l walltime=0:05:00
cd $PBS_O_WORKDIR
mkdir test$var
cd test$var
module load R/2.5.0
R --vanilla< test
exit 0
"
The content in R file "test" is :
"rm(list=ls(all=TRUE))
sample(10)
"
I expect to have different samples each time. However, for these 5  
replications, the first 3 jobs giving me the same samples and the last  
2 are the same. I'm confused because I already used "R --vanilla" to  
avoid loading same workspace each time and "rm(list=ls(all=TRUE))" to  
remove the same random seed each time. Why do same samples still  
happen among 5 replications? Does anybody have some ideas to solve  
this problem? Looking forward to your reply, thanks.

Regards,
Jiqiu

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