bash script to read table line by line - bash

Question

Sample Input: (tab separated values in table format)
Vserver Volume Aggregate State Type Size Available Used%
--------- ------------ ------------ ---------- ---- ---------- ---------- -----
vs1 vol1 aggr1 online RW 2GB 1.9GB 5%
vs1 vol1_dr aggr0_dp online DP 200GB 160.0GB 20%
vs1 vol2 aggr0 online RW 150GB 110.3GB 26%
vs1 vol2_dr aggr0_dp online DP 150GB 110.3GB 26%
vs1 vol3 aggr1 online RW 150GB 120.0GB 20%
I've a task to find the volumes under an aggregate which has breached threshold so that they can be moved to a different aggregate.
Need your help to read the above table line by line, capture volume associated with a specific aggregate name (which will passed as an argument) and add the size of the volume to variable (say total). The next lines should be read till the variable, total is less than or equal to the size that should be moved (again which will passed as an argument)
Expected output if <aggr1> and <152GB> are passed as arguments
vol1 aggr1 2GB
vol3 aggr1 150GB

Answer 1

You want to read the file line by line, so you can use awk. You give arguments with the syntax -v aggr=<aggr>. You will enter that on command line:
awk -f script.awk -v aggr=aggr1 -v total=152 tabfile
here is an awk script:
BEGIN {
if ( (aggr == "") || (total == 0.) ) {
print "no <aggr> or no <total> arg\n"
print "usage: awk -f script.awk -v aggr=<aggr> -v total=<total> <file_data>"
exit 1;}
sum = 0;
}
$0 ~ aggr {
scurrent = $6; sub("GB","", scurrent);
sum += scurrent;
if (sum <= total) print $2 "\t" $3 "\t" $6;
else exit 0;
}
The BEGIN block is interpreted once, at the beginning! Here you initialize sum variable and you check the presence of mandatory arguments. If they are missing, their value is null.
The script will read the file line by line, and will process only lines containing aggr argument.
Each column is referred thanks to $ and its NUM; your volume size is in the column $6.