Problem for picking & manipulating particular line from /PROC/DISKSTAS

[prassaad]

HI!
I 'm working on linux .I hv difficulty for picking particular line from a file...
I like to make some manipulation on LINE such as
3 sda7 333333 66666 888888 444444
from file /PROC/DISKSTATS
how I should proceed???
PLZ reply me if u hv answer......
i m waiting.......

[prn]

I'm afraid I don't have an answer. The reason is that you haven't give me a well-formed question.

You want to pick a particular line from a file. OK. What criteria do you have to select the line? What kind of manipulation do you intend to do?

We can't tell you how to pick a line if we don't know why you want to pick one line rather than another.

Regards,
Paul

[prassaad]

HI!
I 'm working on linux .I hv difficulty for picking particular line from a file...
I like to make some manipulation on LINE such as
3 sda7 333333 66666 888888 444444
from file /PROC/DISKSTATS
how I should proceed???
PLZ reply me if u hv answer......
i m waiting.......

manipulations are :
1.to check how values such as 3333333(in above line )
changes every second i.e.after sleep(1);
2.how i will separate every values in above line...

[prn]

Hi prassaad,

manipulations are :
1.to check how values such as 3333333(in above line )
changes every second i.e.after sleep(1);
2.how i will separate every values in above line...

That's still not very clear. I'll make some assumptions. Assuming that you want to pick the line with sda7, your script can just grep for sda7. To separate the elements of the line, you can use cut. Also, note that the fields in /proc/diskstats are separated by an unknown number of spaces, as in:

 
   3    1 hda1 1282 2570 23 46
   3    2 hda2 244191 3961445 2621545 20972360
   3   64 hdb 11056 4657 473450 256563 60696 17135 623128 330075 0 150236 586641
   3   65 hdb1 15595 472418 77894 623128

so you may need to "squash" them together to get a single space. Thus, if I wanted to extract the field immediately following "hda2" in the excerpt above, I might write:

#! /bin/sh
while [ true ]
do
    grep hda2 /proc/diskstats | tr -s ' ' | cut -d ' ' -f5
    sleep 1
done

Without knowing any more than you have told us, that's about the best anyone can do for you.

HTH,
Paul