Shell Programming and Scripting

HI ,
I am wrirting a script for checking the performance monitoring on Linux System when my application is running.
I have to run a test for 30 minutes on some server and while the test is running i have to capture the perfromance metrics of Linux through vmstat , sar, mpstat, free.
here is the script

Code:

vmstat 1 | awk '{now=strftime("%d-%m-%y     %H:%M:%S    "); print now $0}'> ~/vmstats.txt &

or

Code:

c=0;while [ c != 1800 ]; do vmstat -t 5 ; c=expr`c+1`; done # this will run for 30 minutes

Here i am seeing an issue like :
i am seeing getting the headers as well in the output file(vmstats.txt) which i dont want to have in the output file, as i need to plot graphs of the runnable threads, cs, bi/bo later when the test is completed
Header is

Code:

02-06-13     11:38:53    procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----

Please help me in resolving this issue.

Code:

==================================================
sar -B 1 | awk '{now=strftime("%d-%m-%y    "); print now $0}'> ~/paging_report.txt &
>> This script is running file

One quick way is to pipe it through 'tail' only outputting line 2 through the end:

Code:

tail --lines=+2

I realize that the original question is specific to linux, but, still, I see no reason to use --lines instead of the ubiquitous -n.

However, I can think of at least two reasons not to: (1) Even if only by a trivial amount, it increases the learning curve for a new Linux admin with a non-GNU userland background. (2) Novice UNIX scripters may be frustrated when their GNU-only code doesn't run a non-GNU system.

Regards,
Alister

Yes i had solved the problem of mine yesterday only , i should be using -n swtch to repeat headers of vmstat in the output file. manual of vmstat served the purpose:-)
Thanks Alister, u got it right :-)