Sort unix folders by size

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du -ks * | sort -n -r

 

Validate firewall connectivity using nc

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In absence of telnet we can use nc (which version??) to validate connectivity.

nc -w 2 -v 10.0.0.1 < /dev/null; exitCode=$?; echo "Exit code = $exitCode"; if [ $exitCode -ge 1 ]; then echo "No connectivity"; else echo 'SUCCESS!!!'; fi; >> fw_validation.txt

To setup a simple log monitoring script

// TODO


#! /bin/bash
echo "monitoring log files"
if grep SQLSTATE application-cronjob-*-`date +"%Y-%m-%d"`.log ;
then
    echo "sending mail"
    grep -10 SQLSTATE application-cronjob-*-`date +"%Y-%m-%d"`.log | mail -s "errors found in  logs for `date +"%Y-%m-%d"` example@example.com
fi

Bash for loop examples

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For loop example in bash script:
To get yarn log files for multiple spark jobs, we can use this command.
for i in `cat appid.txt`; do echo $i; yarn logs -applicationId $i > sparkjob_01sep_logs/$i.log; echo "——"; done




For loop with sequence and ssh into multiple servers:
To login into multiple servers and run a command, we can use below command.

for i in `seq 101 125`;do ssh -q machinename$i "hostname;ls -ltr";done

To get http status code from curl call

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We can use below command to get http response code of a URL from bash script.

status_code=$(curl --write-out "\n%{http_code}\n" --silent --output /dev/null --insecure https://www.google.co.in/)

silent - to stop progress information in output
output - we are re-directing normal output to null device
write-out - whatever things we needed can be given here. Here we are printing http status code. It will be printed after completion, i.e., after printing all output.
insecure - this allows connections to SSL sites without certs

References: http://stackoverflow.com/a/2220646/324900