OS commands

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To watch CPU core interrupts:

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/usr/bin/watch -d 'cat /proc/interrupts'

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To increase WAN transfers, increase txqueuelen in eth interface:

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“For WAN transfers, it was discovered that a setting of 2,000 for the txqueuelen is sufficient to prevent any send stalls from occurring.”5 Default value for txqueuelen is 1000. I have successfully tested a value of 2500. Type the follow command to change it: 

Example:

ifonfig eth4 txqueuelen 2500

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# To run the application or commands to a specific core "numactl" 

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#get the cpu physical core info from the below and use it in numactl.

less /proc/cpuinfo

numactl --physcpubind=1

Ex:  numactl --physcpubind=1 top

This will run the top command using physical cpu core id "1"

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#To Check the ethernet interface driver version:

ethtool -i eth0

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#To get Inode number for a group a files in a folder

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cd /test

stat * |grep -i -E 'File:'\|'Inode' | awk '{ if($3 == "Inode:") print "   "$3" "$4; else print $0 }'

#Good Format:

stat * |grep -i -E 'File:'\|'Inode' | awk '{ if($3 == "Inode:") print "\t"$3" "$4; else print $1 $2 }' |awk 'NR%2{printf "%s ",$0;next;}1'

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#To process any operation line by line in do while loop:(Example)

filename=/tmp/file1.txt

while read -r line

do

    name="$line"

    echo "Name read from file - $name"

done < "$filename"

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#To extract the logs between two timestamps 

Example:

sort hiveserver2.log |sed -n '/2017-04-26 20:40:44/,/2017-04-26 20:43:44/p' >> extracted_file.log

or

sed -n '/2017-04-26 20:43:44/,/2017-04-26 20:43:44/p' hiveserver2.log  >> extracted_file.log

cat hiveserver2_knox_25_april1 |grep -a ''  |sort  |sed -n '/2017-04-25 20:/,/2017-04-25 21:/p' > hiveserver2_8:30PM_9:30PM

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##Monitor I/O using SAR command:

sar -d -p 1

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Mac OS : converting delimiter $ to ','

perl -pi -w -e 's/\$/,/g;' test1.txt

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Hive Server(HS2) open files group by PID :-

grep 'open files' /proc/$(ps aux | grep -i "hiveserver2"|grep -v 'grep'|  awk '{print $2}')/limits

lsof -u hive |awk '{print $2}' |uniq

lsof -u hive |awk '{print $2}' |sort |uniq -c

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