Hi,

I want to redirect the tar output when creating .tar file.

CASE 1:
when i run command " time tar -c /mnt/my_hierarchy > /dev/null "

time required is very less, and tar even do not go to read the file.

CASE2:

when i run command "time tar -c /mnt/my_hierarchy > /dev/zero"

now time required is large, and i can see the read calls happening.


I know /dev/zero is not for redirecting output to that device but, when i
googled around i found that, there is no difference in
redirecting output to /dev/null or to /dev/zero , only difference is when
you use /dev/zero as input then you get zeros which is not
the case with /dev/null.


If my information and understanding above is right, then why am i getting
these different time when i perform tar on same hierarchy?
Also why tar do not read the file when its output is redirected to
/dev/null?


I want to measure performance in terms of time required to perform tar on a
given hiearchy. so I am not sure which command is correct.

I will be thankful if some one can help me / guide me on this.


Thanks,
Shreyas
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