Shell Programming and Scripting

 
$ nawk '/%/ {a=substr($(NF-1),1,length($(NF-1))-1); if(a > 30){print $0}}' test                                                                   
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3              20G   13G  6.2G  68% /
                      400G  272G  129G  68% /oradata
                      1.1T  526G  578G  48% /orabkup
                      2.3T  1.6T  728G  69% /software
                      2.3T  1.6T  728G  69% /backup
                      2.3T  1.6T  728G  69% /patches
                      450G  170G  281G  38% /xyz_oradata
                      150G   67G   84G  45% /orabin
                      225G  106G  120G  48% /oradata_xxx
                       40G   20G   21G  48% /orabin
                       40G  1.4G   39G   4% /oradata2

 
bash-3.00$ cat test 
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3              20G   13G  6.2G  68% /
/dev/sda1              99M   21M   74M  22% /boot
fcsan02:/vol/xxx_oradata
                      400G  272G  129G  68% /oradata
fcnas01:/vol/oraclebackups/xxx
                      1.1T  526G  578G  48% /orabkup
fcnas01:/vol/ebs/software
                      2.3T  1.6T  728G  69% /software
fcnas01:/vol/ebs/backup
                      2.3T  1.6T  728G  69% /backup
fcnas01:/vol/ebs/patches
                      2.3T  1.6T  728G  69% /patches
fcsan03:/vol/xxx_xxoradata
                      450G  170G  281G  38% /xyz_oradata
fcsan03:/vol/xxx_scripttest
                       20G   96K   20G   1% /scripttest
fcsan03:/vol/orabin/xxx
                      150G   67G   84G  45% /orabin
fcsan01:/vol/ebs/eptp51
                       10G  5.5M   10G   1% /ebs/eptp51
fcsan02:/vol/SnapManager_20101206155612743_xxx_oradata
                      225G  106G  120G  48% /oradata_xxx
tmpfs                 9.8G   28M  9.8G   1% /dev/shm
fcsan03:/vol/xxx_oraerp
                       40G   20G   21G  48% /orabin
fcsan03:/vol/xxx_archerp
                       40G  1.4G   39G   4% /oradata2

 
TEST_SYSTEM>df -h | awk '/%/ {$0=(a?a" "$0:$0);a="";gsub("%","");print $0;next} {a=$0;next}' | awk '$5>30' > disk_chk_out
TEST_SYSTEM>mailx -s "Disk Check > 30%" abc@xyz.com < disk_chk_out

 
$ df -h | nawk '/%/ {if(length($(NF-1))> 2) {a=substr($(NF-1),1,length($(NF-1))-1); if(a > 30){print $0}}}'

$ df -h | nawk '/%/ {if(length($(NF-1))> 2) {a=substr($(NF-1),1,length($(NF-1))-1); if(a > 30){print $0}}}'

 
nawk '/%/ {if(length($(NF-1))> 2) {a=substr($(NF-1),1,length($(NF-1))-1); if(a > 30){print $0}}}'

/%/  --> Match % and process the lines which is having %
$(NF-1) --> Print the value of (last - 1) column value (disk usage column)
length($(NF-1)) --> Get the length of the disk usage column.
if(length($(NF-1))> 2  --> check the length is greater than 2 ( It will eliminate the usage which is less than 10%)
a=substr($(NF-1),1,length($(NF-1))-1);  --> Strip the % value from the disk usage column ( eg: 85% to 85 )
then check a > 30, then print the line.
More example for understaing :
echo "abc edf ghi" | awk '{ print $NF }'            # prints the last record value
echo "abc edf ghi" | awk '{ print $(NF-1) }'  # prints the last-1 record value
echo "abc edf ghi" | awk '{ print $(NF-2) }'  # prints the last-2 record value
echo "abcd efg hi" | awk '{print length($1)}'  # prints the lenght of first record
echo "abcd efg hi" | awk '{print length($2)}'  # prints the lenght of second record
echo "abcd efg hi" | awk '{print length($3)}'  # prints the lenght of third record
echo "abcdefg" | awk '{ print substr($0,1,2)}'   # prints 2 letters from the 1st position